Chapter 8. Foot and Ankle Surgery

The primary role of the foot and ankle is locomotion. Therefore, it is critical for the clinician treating disorders of the foot and ankle to have the knowledge and understanding of the anatomy and biomechanic principles of the foot and ankle. The following is a limited discussion of the biomechanic principles governing the foot and ankle during the gait cycle. Once these principles are familiar and understood, it will enable the clinician to make diagnoses of problems that affect the anatomy and function of the foot and ankle.

Gait

Gait is the orderly progression of the body through space while expending as little energy as possible. As the body moves through a gait cycle, muscle forces are generated actively to counteract the passive effects of gravity on the body. To accommodate these forces, the foot is flexible at the time of heel strike to allow for absorption of impact of the body against the ground. However, at the end of stance phase, the foot becomes rigid at toe-off, when it must assist in moving the body forward. The magnitude of the forces on the foot increases significantly as the speed of gait increases. For example, when an individual is walking, the initial force with which the foot meets the ground is approximately 80% of body weight. With jogging, the force increases to approximately 160%. Also, the peak force against the foot during walking is 110% of body weight, and for jogging 240%. This marked increase contributes to some of the injuries seen in runners.

The Walking Cycle

Gait analysis has been described in Chapter 1, but further detail of the role of the foot and ankle are described here (Figures 8–1 and 8–2). An important component of the physical examination is observation of the patient during the walking cycle. This will help the physician with the cause of a gait anomaly. For example, an equinus deformity from spasticity or contracture will cause the toe to make initial contact with the ground rather than the heel. Furthermore, at 7% of the gait cycle, the foot is usually flat on the ground, but spasticity or contracture of the Achilles tendon causes this to be delayed. At 12% of the cycle, the opposite foot toes off and the swing phase begins. Heel rise of the standing foot begins at 34% of the cycle as the swinging leg passes the standing limb. With spasticity, heel rise may occur earlier, and in contrast, with gastrocsoleus weakness, heel rise will be later. Heel strike of the opposite foot occurs at 50% of the cycle, ending the period of single-limb support; and may occur sooner if there is weakness of the contralateral gastrocsoleus muscle. Toe-off of the opposite foot occurs at 62% of the cycle, at the beginning of the swing phase. These markers of the gait cycle should be kept in mind when observing gait, so pathologic conditions may be identified.

Motions of the Foot and Ankle

The majority of dorsiflexion and plantar flexion occurs through the ankle joint. The subtalar joint allows for inversion (varus) and eversion (valgus). Next, adduction, which is movement toward the midline, and abduction, which is movement away from the midline, occurs through the transverse tarsal joint (talonavicular and calcaneocuboid joints). Supination and pronation are used in describing combinations of movements, but unfortunately, these terms are sometimes used in the literature interchangeably. Supination is a combination of plantar flexion of the ankle joint, inversion of the subtalar joint, and adduction of the transverse tarsal joint. Pronation is the exact opposite movement: dorsiflexion of the ankle joint, eversion of the subtalar joint, and abduction of the transverse tarsal joint. The nomenclature may also be confusing when such terms as forefoot varus and forefoot valgus are used (Figure 8–3). Forefoot varus or valgus is an anatomic deformity that is observed when the hindfoot is placed in neutral position. Neutral position is achieved when the calcaneus is aligned with the long axis of the tibia and the head of the talus is covered with the navicular bone. Forefoot varus deformity is present when the lateral aspect of the forefoot is in greater plantar flexion than the medial aspect. With a flexible deformity, the foot lies flat on the floor during stance, but with a fixed deformity, excessive weight is borne on the lateral side of the foot. As a result, as the weight passes onto the forefoot, the calcaneus goes into valgus position, and this may result in lateral impingement of the calcaneus against the fibula if severe. In forefoot valgus deformity, the medial side of the foot has greater plantar flexion than the lateral side and results in excessive weight bearing by the first metatarsal head. To accommodate for this deformity, the calcaneus assumes a varus position, which may result in a feeling of instability at the ankle joint.

Mechanisms of the Foot during Weight Bearing

During gait, the foot is flexible at heel strike to absorb the impact of striking the ground. As a result, the subtalar joint literally collapses into a position of valgus, causing internal rotation of the tibia and resulting distally in unlocking of the transverse tarsal (talonavicular and calcaneocuboid) joint. This allows the foot to be flexible. During this part of the gait cycle of heel strike, the anterior compartment muscle group is the only muscles that are active. The anterior compartment muscles control the initial rapid plantar flexion following heel strike by an eccentric or lengthening contraction. The flexibility of the foot is greatest at approximately 7% of the cycle. As the body passes over the foot in foot flat, the heel up begins to rise and then forces the metatarsophalangeal joints into extension. As this occurs, the foot is converted into a rigid lever that supports the body at the time of toe-off. The mechanisms that bring about conversion of the foot from a flexible to a rigid structure are (1) the tightening of the plantar aponeurosis, the windlass mechanism; (2) the progressive external rotation of the lower extremity, which begins at the pelvis and is passed distally across the ankle joint into the subtalar joint; and (3) the stabilization of the transverse tarsal joint, which results from the progressive inversion of the subtalar joint.

Joints of the Foot and Ankle

Ankle Joint

The ankle joint is the articulation of the talus with the tibia and fibula and has a range of motion (ROM) of 15 degrees of dorsiflexion to 55 degrees of plantar flexion. There is also a small amount of motion in the transverse plane, approximately 15 degrees. The anterior compartment muscles of the leg, the tibialis anterior and the toe extensors, control the amount of plantar flexion of the ankle joint at the time of heel ground contact to 10% stance. These muscles are responsible for dorsiflexion of the foot and ankle during swing phase. Any weakness or pathology affecting the anterior compartment may result in a footslap at heel strike and a dropfoot during swing phase. The greatest force across the ankle joint during walking is calculated to be approximately 4.5 times body weight, which occurs at 40% of the walking cycle.

Subtalar Joint

The subtalar joint is the articulation between the talus and the calcaneus. There are three components of this joint, the posterior, middle, and anterior facets. The most important and largest of these facets is the posterior facet. Through the subtalar joint, inversion of approximately 20 degrees and eversion of approximately 5–10 degrees occurs. These motions are brought about by the tibialis posterior muscle (inversion) and the peroneus brevis (eversion). During the walking cycle at initial ground contact, eversion is a passive mechanism and occurs because of the shape of the articulations and their ligamentous support. Inversion occurs both actively and passively at the time of toe-off. Active control is achieved by the gastrocsoleus and posterior tibial muscles, and passive inversion occurs by the action of the plantar aponeurosis, the external rotation of the lower extremity, and the oblique metatarsal break.

Talonavicular Joint and Calcaneocuboid Joint

The talonavicular and calcaneocuboid joints functionally act as a single joint, also called the transverse tarsal joint. The transverse tarsal joint is responsible for adduction and abduction, 15 degrees and 10 degrees, respectively. The head of the talus is firmly seated into the navicular at the time of toe-off, adding stability to the foot. Also, the stability of the transverse tarsal joint is controlled by the position of the subtalar joint. When the subtalar joint is in an inverted position, the axes of these two joints are nonparallel, giving rise to increased stability of the hindfoot. When the calcaneus is in an everted position at the time of heel strike, these joints are parallel to one another, thereby giving rise to increased flexibility of these joints (Figure 8–4). An important aspect of this position is that when the position of a subtalar arthrodesis is determined, careful alignment into 5–7 degrees of the subtalar joint will maintain the foot's flexibility and ability to walk. However, if the subtalar joint is placed in a malposition of hindfoot varus, the transverse tarsal joint will be locked. The resulting foot will be stiff, and the patient will have difficulty with walking.

Metatarsophalangeal Joints

The metatarsophalangeal joint is the articulation of the metatarsal head and base of the proximal phalanx. The normal motion at this joint is 50–70 degrees of dorsiflexion (extension) to 15–25 degrees of plantar flexion (flexion). The importance of this joint in the walking cycle is discussed in detail the following section on the first toe.

The Plantar Aponeurosis

Although the plantar aponeurosis is not an articulation per se, it probably plays the predominant role in the overall stability of the foot. The plantar aponeurosis originates from the tubercle of the calcaneus and inserts on the base of the proximal phalanges (Figure 8–5). During gait, the metatarsophalangeal joints extend at the last half of the stance phase. The plantar aponeurosis forces the metatarsal heads into a plantarward direction, which raises the longitudinal arch, and this is known as a windlass mechanism. Additionally, the plantar aponeurosis increases the effect that a tensile force in the Achilles tendon has on the tensile force in the plantar fascia. The result is a rigid foot that allows for the body to push-off during gait. Also, this mechanism helps to invert the subtalar joint, thereby increasing the rigidity of the foot for push-off.

Gait Abnormalities

Common disorders of gait are described.

Pes Planus Deformity

Pes planus is a decreased longitudinal arch. This may occur when the patient has hypermobility of the joints and the foot is too flexible. As a result, the gait pattern is abnormal; there is excessive valgus of the hindfoot and, in severe cases, breaking down of the longitudinal arch. The forefoot becomes abducted at the beginning of the gait cycle, and there is increased weight-bearing surface on the plantar aspect of the foot. This may cause easy fatigability because of the lack of adequate support of the longitudinal arch.

Cavus Deformity

A cavus deformity is an excessive elevation of the longitudinal arch. Frequently, there is an associated decrease in the motion the foot, and the hindfoot is in varus while the forefoot is in valgus. Also, the toes may assume a claw deformity. Clinical examples of this deformity are Charcot-Marie-Tooth disease, poliomyelitis, and sometimes chronic stage compartment syndrome of the leg. The overall effect is decreased surface area for weight bearing. Furthermore, claw toe deformities may reduce contact with the ground more. As a result, the gait pattern is abnormal, and increased pressure on the heel at heel strike is seen. With the progression of gait, there is increased pressure of the lateral plantar aspect of the foot and the first metatarsal head.

Dropfoot Gait

Weakness of the anterior tibialis muscle or a common peroneal nerve palsy may result in a dropfoot gait. These patients lack ankle dorsiflexion, and so the ankle plantar flexes at the ankle joint. When walking, these patients adopt a steppage-type gait. This gait pattern is manifested by increased flexion of the hip and knee to enable the swinging leg to clear the ground. If this compensatory mechanism does not occur, the patient may catch the toes on the ground and fall.

Equinus Gait

An equinus contracture can occur if there is anterior compartment weakness, which results in uncompensated pull of the gastrocsoleus complex. Also, equinus contracture may be caused by a stroke or head injury, trauma to the lower extremity, or a congenital deformity, and it often is associated with tightness of the posterior capsule. The ankle is fixed in plantar flexion throughout the entire gait cycle. This gait pattern is characterized by forefoot floor contact only. The heel does not touch the ground. The anterior loading of the foot results in a back knee thrust, which may, over a long period of time, result in a hyperextension deformity of the knee. A weak quadriceps muscle may accentuate this problem.

Biomechanic Principles

The first metatarsophalangeal joint functions mainly as a weight-bearing structure and stabilizer of the medial aspect of the longitudinal arch. The static stability of the first metatarsophalangeal joint is provided by the collateral ligaments and the strong plantar plate, which consists of the plantar aponeurosis and the joint capsule. Added dynamic stability is provided by the abductor hallucis and adductor hallucis muscles, which insert along the medial and lateral sides of the metatarsal head, respectively. No muscle inserts into the metatarsal head per se, and therefore, it is suspended in a sling of muscles and tendons. This allows the metatarsal head to be pushed in a medial or lateral direction, depending on the deviation of the proximal phalanx.

The plantar aponeurosis forces the metatarsal heads into plantar flexion during the last third of the stance phase of the walking cycle. The hallux experiences greater pressure as it is transferred from the metatarsal heads to the toes (see Figure 8–5). If this windlass mechanism for the hallux is lost as occurs in a bunion deformity, pressure is no longer transferred to the toes but remains beneath the metatarsal heads. Metatarsalgia results from this transfer of load, especially beneath the lesser metatarsal heads. The second metatarsal frequently bears the load because the weight-bearing ability of the first metatarsal is disrupted.

Changes to the normal biomechanics of this joint may result in a transfer lesion, which is a hyperkeratotic lesion under the lesser metatarsal heads. The most common cause is a surgical procedure that disrupts this mechanism, such as a Keller arthroplasty. In this procedure, the base of the proximal phalanx is removed, thereby disrupting the insertion of the plantar aponeurosis into the hallux. Also, prosthetic replacement of the first metatarsal joint will result in loss of this mechanism. Metatarsal osteotomy with excessive shortening (>5–7 mm) or dorsiflexion of the first metatarsal may also cause this problem.

Normal Anatomy

The first metatarsophalangeal joint is complex. It is made up of the articular surface of the metatarsal head and the base of the proximal phalanx, along with the two sesamoid bones plantarly. The sesamoids are connected by an intersesamoidal ligament, separated by a bony crista, and lie within the dual tendons of the flexor hallucis brevis. Medially and laterally, the collateral ligaments stabilize the metatarsophalangeal joint, and toward the plantar surface, they blend with the adductor and abductor hallucis tendons along the lateral and medial sides of the joint. Further toward the plantar surface, the sesamoids are stabilized by the firm attachment of the encapsulating plantar aponeurosis, which inserts into the base of the proximal phalanx. Plantar to the sesamoids passes the flexor hallucis longus tendon. Dorsally, the extensor hallucis longus tendon is stabilized by a medial and lateral hood mechanism similar to that present in the hand, and the extensor digitorum brevis muscle inserts into the proximal phalanx along the lateral aspect of the joint. Normal motion of the metatarsophalangeal joint consists of dorsiflexion and plantar flexion.

Hallux Valgus

Hallux valgus is also known as a bunion deformity (ICD-9 735.0). It is a complex deformity that includes lateral deviation of the proximal phalanx and the resultant medially directed pressure exerted against the metatarsal head. The medial eminence becomes prominent as the proximal phalanx drifts into a valgus position. With chronic deformity, the medial joint capsule becomes attenuated, and the lateral joint capsule becomes contracted. As the metatarsal head is pushed medially, the sesamoids, which are firmly anchored by the adductor hallucis tendon and transverse metatarsal ligament, slowly erode the crista. This allows for lateral subluxation of the sesamoids from directly plantar to the first metatarsal. With the lateral deviation of the hallux, the extensor hallucis longus and flexor hallucis longus assume a lateral position and contribute to the lateral forces on the hallux. With a severe deformity, both the extrinsic and intrinsic muscles lie lateral to the longitudinal axis of the first metatarsophalangeal joint, thereby further enhancing the deformity. As the deformity progresses, pronation of the hallux occurs because attenuation of the weakest portion of the capsule (the dorsomedial aspect) allows the abductor hallucis tendon to slide beneath the metatarsal head and rotate the proximal phalanx into a position of pronation. More rapid progression of the deformity may occur in a small percentage of patients whose first metatarsocuneiform joint demonstrates a significant degree of instability.

General Considerations

The incidence of hallux valgus deformity is 10 times greater in women than in men. The incidence is also significantly higher in shod populations than unshod ones. The conclusion can therefore be made that a major contributing cause of hallux valgus deformity is wearing constricting shoes. Other factors that may contribute to hallux valgus are familial history of bunions, bilateral involvement, female gender, a long first ray, an oval or curved metatarsophalangeal joint articular surface, spasticity, and systemic disease such as rheumatoid arthritis. Furthermore, hallux valgus deformity is not associated with chronic tightness of the Achilles tendon or gastrocnemius, increased first ray mobility, bilaterality, or pes planus.

Clinical Findings

Symptoms and Signs

The most common symptom is pain over the medial eminence. Patients also complain of pain in the joint and pain under the second metatarsal head (transfer lesion or metatarsalgia). The deformity may prevent shoewear, and the activity limitation may be part of the constellation of symptoms. The patient's occupation, sports activities, and typical shoewear should be noted.

A complete evaluation is performed on both lower extremities with the patient undressed from the knees to the toes. The patient is instructed to stand and walk. The posture of the foot is noted as well as the position of the hallux and lesser toes. The skin is evaluated for erythema, swelling, ulceration, or callosities. The ROM is checked for the ankle, subtalar, transverse tarsal, and metatarsophalangeal joints. The neurovascular status of the foot is carefully assessed, noting absent pulses and venous stasis changes. If there is compromise of the vascularity, then vascular studies may be obtained. Doppler studies are obtained if there is any question regarding the circulatory status of the foot. It is important to note the ROM of the first metatarsophalangeal joint in the deformed and corrected position. The amount of motion limitation will give the surgeon insight into the degree of surgical correction that can be obtained at the joint without impairing motion of the joint. The first metatarsocuneiform joint is examined for hypermobility by stabilizing the medial cuneiform and ranging the first metatarsal dorsomedially and plantolaterally.

Imaging Studies

Weight-bearing radiographs of the foot are important to evaluate the type and severity of the hallux valgus deformity. Radiographic evaluation of the first metatarsophalangeal joint includes:

1. The hallux valgus angle: The angle created by the intersection of the lines that longitudinally bisect the proximal phalanx and first metatarsal. A normal angle is less than 15 degrees (Figure 8–6).

2. The 1,2 intermetatarsal angle: The angle created by the intersection of the lines bisecting the first and second metatarsal shafts. A normal angle is less than 9 degrees (Figure 8–6).

3. The distal metatarsal articular angle: The angle of the distal articular surface of the first metatarsal to the long axis of the metatarsal. Normal is less than 10 degrees of lateral deviation.

4. Congruency of the first metatarsophalangeal joint: A congruent joint has no lateral subluxation of the proximal phalanx in relation to the first metatarsal head, and an incongruent joint has lateral subluxation of the proximal phalanx on the metatarsal head (Figure 8–7).

5. The first metatarsocuneiform joint: The angle is based on the distal articular surface of the medial cuneiform and the longitudinal axis of the first metatarsal. Excessive medial deviation may indicate that hypermobility may be present.

6. Arthrosis of the metatarsophalangeal joint has joint space narrowing, subchondral sclerosis, and osteophyte formation.

7. The medial eminence: The characteristics are evaluated, especially size, as measured from the sagittal groove on the medial aspect of the first metatarsal shaft.

8. The hallux valgus interphalangeus is present when there is lateral deviation of the proximal or distal phalanx, or both, in relation to a line drawn across the base of the proximal phalanx. Normal is less than 10 degrees of lateral deviation.

Treatment

Nonoperative Treatment

As with all forefoot disorders, proper shoewear is important for successful conservative management. The patient should be encouraged to wear shoes of adequate size and shape. This simple form of management may relieve most symptoms. Padding is helpful to alleviate symptoms associated with the bunion deformity. Pads may be placed in the first web space or over the median eminence to help take pressure off a painful median eminence. Pads are also available that can be placed underneath the metatarsal heads to take pressure off painful calluses or sesamoids. In some patients, custom orthotic devices are helpful. These, too, will decrease pressure in symptomatic areas. Patients who fail these treatment options may consider surgical treatment to correct the deformity. An operation is not performed for cosmetic reasons or to allow patients to wear fashionable shoes, but rather to correct a symptomatic structural deformity.

Juvenile hallux valgus deformity is considered a different entity than adult hallux valgus. These patients may be challenging to treat, but as a general rule, nonoperative management should be continued until growth is completed, after which surgery may be considered. Extra care must be taken into consideration in the juvenile population where cosmetic appearance may play a greater role in the patient's or parents' desire for surgery. Hallux valgus surgery is generally contraindicated in high-performance athletes or dancers until they are no longer able to perform at the level necessary to continue in their vocation or avocation. Premature surgery in these individuals may diminish their special abilities.

Surgical Treatment

Algorithm for Surgical Treatment

The patient's symptoms, the physical signs, and the radiographic findings must be taken into account in determining the best operation for that patient. It must be emphasized that there is not a single procedure appropriate for all hallux valgus deformities. Preoperative planning with all these considerations is important.

The following factors need to be considered in the decision-making process:

1. Patient's chief complaint

2. Physical findings

3. Degree of hallux valgus and intermetatarsal angle

4. Distal metatarsal articular angle

5. Congruency or incongruency of the metatarsophalangeal joint

6. Presence of arthrosis of the joint

7. Degree of pronation of the hallux

8. Age of the patient

9. Circulatory status

10. Patient expectations for outcome of operation

The algorithm in Figure 8–8 divides hallux valgus deformities into three main groups: those with a congruent joint, those with an incongruent joint, and those associated with degenerative joint disease. The algorithm lists the operative procedure that may best correct the deformity within each classification. Although no one scheme is all inclusive, this algorithm is helpful in organizing the treatment plan.

The first step is to evaluate the first metatarsophalangeal joint for congruency. A congruent metatarsophalangeal joint generally requires excision of the large and symptomatic medial eminence, and the joint does not require realignment. For a mild to moderate deformity, a chevron osteotomy with or without an Akin procedure yields good to excellent results.

With an incongruent joint, the proximal phalanx is subluxed laterally on the metatarsal head. The operative procedure necessitates that the proximal phalanx be reduced onto the metatarsal head. The procedure of choice depends on the severity of the deformity (see Figure 8–8).

If the first metatarsocuneiform joint is hypermobile, a distal soft-tissue procedure with a metatarsocuneiform arthrodesis (Lapidus procedure) may be indicated. With a severe hallux valgus deformity, a greater than 45- to 50-degree hallux valgus angle, and degenerative joint disease, arthrodesis of the joint is indicated. If routine hallux valgus repair is attempted in the patient with advanced arthrosis, stiffness of the metatarsophalangeal joint frequently results. Use of a prosthetic replacement, as a general rule, does not produce a satisfactory long-term result, particularly in active individuals.

Surgical Procedures

Distal Soft-Tissue Procedure

The McBride procedure was a commonly performed operation (CPT 28292). It was modified by DuVries, followed by additional modifications, and is now called the distal soft-tissue procedure. The procedure used by itself is appropriate in mild hallux valgus deformities, where the intermetatarsal angle is less than 12–13 degrees and the hallux valgus angle is less than 30 degrees. Within this range of deformity, a satisfactory outcome can usually be anticipated from this procedure.

The distal soft-tissue procedure involves a medial incision to expose the metatarsophalangeal joint. The joint is inspected, and the medial eminence is removed 1–2 mm just medial to the sagittal sulcus and in line with the medial aspect of the metatarsal shaft. A second incision in the first interspace allows for releasing the soft-tissue contracture on the lateral side of the metatarsophalangeal joint. These structures include the lateral joint capsule, the adductor hallucis tendon, and the transverse metatarsal ligament (Figure 8–9). Once released, the medial side of the joint is plicated to hold the toe in correct alignment. Postoperatively, the patient is maintained in a firm compression dressing in the correct alignment, and the dressing is changed on a weekly basis for 8 weeks. During this period, the patient is permitted to ambulate in a postoperative shoe.

The most common complication consists of recurrence of the deformity, usually because the deformity was too severe to be corrected by the procedure. In these cases, a metatarsal osteotomy added to the distal soft-tissue procedure completes the correction.

Hallux varus deformity is a medial deviation of the proximal phalanx on the metatarsal head, a complication that may occur in approximately 5–7% of cases. This deformity is usually a result of excessive excision of the medial eminence or fibular sesamoidectomy, which causes joint instability. Occasionally, the medial joint capsule is overplicated or the lateral joint capsule fails to attain adequate strength. Mild hallux varus deformity, up to 7–10 degrees, usually is of no clinical significance unless the joint is also hyperextended.

Distal Soft-Tissue Procedure with Proximal Metatarsal Osteotomy

A proximal metatarsal osteotomy (CPT 28296) will increase the correction of the distal soft-tissue procedure. A proximal metatarsal osteotomy will correct an increased 1,2 intermetatarsal angle, such as a deformity greater than 12–13 degrees, whereas the distal soft-tissue procedure alone cannot. Realignment of the fixed bony deformity present between the first and second metatarsals permits the combined procedure to be used for deformities with up to 50 degrees of hallux valgus and a 25-degree intermetatarsal angle.

The distal soft-tissue procedure is performed, as previously described. Another incision, based over the base of the first metatarsal, is made. A crescentic-shaped saw blade is used to create a crescentic osteotomy, in which the concavity is directed proximally (Figure 8–10). This enables the surgeon to rotate the metatarsal head laterally as the metatarsocuneiform joint is pushed in a medialward direction. This usually results in approximately 2–3 mm of lateral displacement of the osteotomy site. A single cancellous screw placed from the distal fragment into the proximal aspect allows for stable fixation. A popular osteotomy is a chevron cut, or various oblique cuts, opening or closing wedge osteotomies.

Postoperatively, the treatment is the same as for the distal soft-tissue procedure, with 8 weeks of dressing changes and immobilization in a postoperative shoe. As a general rule, cast immobilization is not necessary.

The long-term postoperative results following the distal soft-tissue procedure with proximal osteotomy result in greater than 90% patient satisfaction. The addition of the osteotomy does create an increased risk of complications, but this risk is reported to be uniformly low. Dorsiflexion of the osteotomy site may occur but is usually not of clinical significance. Nonunion of the osteotomy is rare (<1% of cases). Excessive lateral displacement of the metatarsal head can result in hallux varus deformity, which is more resistant to treatment than when osteotomy is not included.

Chevron Osteotomy

The chevron osteotomy is the most common bunion procedure in the United States (CPT 28296). It is indicated for mild to moderate hallux valgus deformities. The procedure is used in deformities when the hallux valgus angle is less than 30 degrees and the 1,2 intermetatarsal angle is less than 12 degrees. The distal metatarsal articular angle should be less than 12 degrees, or complete correction will not be obtained. The operative procedure is based on lateral translation of the metatarsal head, along with plication of the medial joint capsule. The osteotomy is performed through a medial incision to allow removal of the medial eminence. Then, a chevron-shaped cut with the apex based distally is made with a small sagittal saw. The metatarsal head fragment is translated laterally approximately one third of the width of the metatarsal head, or 3–4 mm. The medial bony prominence created by the shift of the metatarsal head is excised and the medial joint capsule plicated. The osteotomy site is fixed with a pin or a screw (Figure 8–11).

Postoperatively, the foot is firmly bandaged for 6–8 weeks in corrected alignment, and the patient is permitted to ambulate in a postoperative shoe. If a pin was used for fixation, it is removed after 4–6 weeks.

Radiographic improvement is seen with high patient satisfaction. In addition, a greater than 10-year follow-up showed consistent improvement with time. There was no difference between patients younger and older than 50 years; patients had equally positive outcomes. However, if the indications are stretched to include more severe deformities, then results may not be satisfactory, with a recurrence or incomplete correction. The most serious complication, occurring in 0–20% of cases, is avascular necrosis of the metatarsal head, which is probably the result of extensive stripping of the soft tissue surrounding the head, especially laterally. The major blood supply to the metatarsal head is from the plantar lateral corner of the metatarsal neck. Therefore, care must be used when performing the saw cut, and the saw should be removed once the osteotomy is completed so as to not injure the vessels on the lateral aspect of the metatarsal head. As with any type of osteotomy, the distal fragment is capable of migrating either too far laterally or medially, giving rise either to hallux varus deformity or recurrent hallux valgus deformity. Occasionally, arthrofibrosis of the joint is noted, resulting in significant joint stiffness.

Akin Procedure

The Akin procedure is useful as an adjunct to a bunion procedure of the first metatarsal (CPT 28298). It involves a medial closing-wedge osteotomy at the base of the proximal phalanx to correct the hallux interphalangeal component of the deformity. It is commonly used with simple excision of the median eminence or with a chevron osteotomy to correct a mild to moderate hallux valgus deformity with a congruent joint. The Akin procedure is indicated for a hallux valgus deformity of less than 25 degrees, with an intermetatarsal angle of 12 degrees or less.

Through a medial incision, the base of the proximal phalanx and the median eminence are exposed. After removing the median eminence in line with the metatarsal, a small sagittal saw is used to remove a wedge of bone from the medial aspect of the proximal phalanx. The osteotomy is closed down and stabilized internally with sutures or wires or externally with a Kirschner wire (K-wire) (Figure 8–12). Dressings are applied for 6–8 weeks postoperatively. Patients may ambulate in a postoperative shoe until the osteotomy has healed.

Keller Procedure

The Keller procedure is seldom indicated as a hallux valgus procedure (CPT 28292). It is reserved for the older, less active patient; in a patient prone to skin problems; or in the case of an arthritic joint. This procedure is contraindicated in an active person because of its known complications.

The procedure involves excision of the base of the proximal phalanx to decompress the metatarsophalangeal joint. Along with the procedure, the medial eminence is removed, and then the intrinsic muscle attachments are repaired to the remaining stump of bone (Figure 8–13). A Kirschner wire is drilled through the toe as a stabilizer until the toe heals and scar tissue forms, approximately 4–6 weeks. Postoperatively, the patient is permitted to ambulate in a postoperative shoe, and dressings are changed for 6 weeks.

Results in the older (>65 years) patient with low functional demand are satisfactory. If the procedure is used in a younger patient, there is instability and loss of weight bearing by the first metatarsophalangeal joint because the base of the proximal phalanx was removed. There is significant loss of foot function, and a transfer lesion may develop beneath the second metatarsal head because the great toe no longer carries adequate weight. The metatarsophalangeal joint develops into a cocked-up deformity with some varus malalignment.

Arthrodesis of the First Metatarsophalangeal Joint

Arthrodesis of the first metatarsophalangeal joint is used in treatment of severe hallux valgus deformities (CPT 28750) with concomitant advanced degenerative arthrosis of the joint or as a salvage procedure following a previously failed surgical attempt to realign the metatarsophalangeal joint. Also, patients with deformities in which the proximal phalanx is subluxed more than 50% of the metatarsal head or who have significant stiffness of the metatarsophalangeal joint should be considered for fusion.

The procedure is performed through a dorsal longitudinal incision, and the joint surface is removed with a sagittal saw to yield two flat surfaces. Alternatively, a dome-shaped reamer may be used to create a ball-and-socket type of configuration. The arthrodesis site is stabilized with an interfragmentary screw and a dorsal plate or Steinmann pins if the bone quality is poor and inadequate screw fixation results. As with any fusion, the position of the arthrodesis is critical; the joint should be placed in 15 degrees of valgus and 10–15 degrees of dorsiflexion in relation to the ground or the plantar aspect of the foot. In relation to the first metatarsal shaft, which is inclined plantarward approximately 15 degrees, it should be in approximately 30 degrees of dorsiflexion (Figures 8–14 and 8–15). Any pronation that is present must also be corrected at the same time.

The patient may ambulate on the heel while wearing a postoperative shoe and progress to full weight bearing in the postoperative shoe until radiographic union is seen, generally in 12 weeks. The unreliable patient may be treated in a short leg walking cast.

The most common complication of arthrodesis of the first metatarsophalangeal joint is malposition. If the toe is not placed into adequate dorsiflexion or valgus, excessive stress occurs against the interphalangeal joint, which may result in a painful arthritic condition of the joint. The fusion rate is 90–95%. In cases of severe hallux valgus deformities, the arthrodesis will correct the hallux valgus angle as well as the increased 1,2 intermetatarsal angle; thus, the need for a proximal osteotomy is unnecessary. Occasionally, the degree of valgus and dorsiflexion is correct but the toe is left in a pronated position, which results in pressure along the medial side of the interphalangeal joint and possible discomfort.

The patient's gait following arthrodesis of the first metatarsophalangeal joint in proper alignment is improved in propulsive power, weight-bearing function of the foot, and stability during gait. These patients are able to roll over the fusion site in an ordinary store-bought shoe, and they may expect to return to normal activities. Squatting is the only activity that is difficult because the toe must be in full dorsiflexion when this activity is carried out. Patients are able to return to most types of athletic activities, although at a somewhat slower pace.

Hallux Rigidus

General Considerations

Hallux rigidus is the name for arthrosis of the first metatarsophalangeal joint (ICD-9 715.17). It is a common entity and frequently affects patients at a much younger age than arthritis of other joints. Hallux rigidus is seen in patients from their thirties onward. The reason why arthritis of this joint is seen in younger patients is unclear but may be associated with an unrecognized chondral injury to the metatarsal head. It is also associated with hallux valgus interphalangeus, bilateral involvement in those with a family history, and female gender. Hallux rigidus is not associated with elevatus, first ray hypermobility, a long first metatarsal, Achilles tightness, abnormal foot posture, symptomatic hallux valgus, adolescent onset, shoe wear, or occupation.

Clinical Findings

Symptoms and Signs

Patients complain primarily of pain of the first metatarsophalangeal joint, especially with extension. Also, the dorsal eminence may prevent shoewear and have associated swelling and redness. Weight bearing and sports activities exacerbate the pain.

Imaging Studies

Weight-bearing radiographs of the foot demonstrate arthritic changes, including loss of joint space, subchondral sclerosis, and the presence of osteophytes, especially on the dorsal aspect of the metatarsal neck.

Conservative Management

Conservative treatment consists of nonsteroidal anti-inflammatory drugs (NSAIDs) and wearing a stiff-soled shoe with a deep toe box. An orthotic device with a Morton's extension or a carbon fiber plate would be beneficial. Both of the devices prevent extension in late stance phase. A rocker-bottom shoe would also be helpful. In older (>60 years), sedentary patients, these measures are usually adequate. In more active individuals, however, surgical treatment is usually indicated.

Surgical Treatment

There are multiple described surgical treatment options for hallux rigidus. Of these, the simplest is a cheilectomy (CPT 28289) and is indicated in patients with mild to moderate arthrosis but who have a large dorsal osteophyte. Approximately one fourth to one third of the dorsal metatarsal head is excised with an osteotome (Figure 8–16). The medial and lateral osteophytes are also debrided, and a thorough synovectomy of the joint is performed. Postoperatively, patients regain up to 50% of their dorsiflexion and have improvement of their total motion. More than 90% of patients have improvement of pain, ability to wear shoes, and increased physical abilities. This procedure is less likely to have a favorable outcome on joints with advanced arthritis.

A Keller procedure is a resection arthroplasty and may be useful in older, less active patients, but it has a high rate of complications, as previously discussed. Prosthetic replacement of the arthritic first metatarsophalangeal joint can be used in older, lower demand patients but has high rates of failure in younger, more active individuals.

First metatarsophalangeal joint arthrodesis is a predictable and durable procedure. The drawback is lost motion at the joint. However, patients can remain quite active with a first metatarsophalangeal joint fusion as described previously.

Sesamoid Disorders

General Considerations

The sesamoid bones are plantar to the first metatarsal head and are part of the first metatarsophalangeal joint complex. Sesamoid disorders can be painful as they are in the weight-bearing part of the foot. Fractures, osteonecrosis, arthritis, and subluxation can affect the sesamoids. A puzzling entity is called sesamoiditis (ICD-9 733.99), which means inflammation of the sesamoids, but it encompasses painful sesamoids without an etiology.

Clinical Findings

Symptoms and Signs

The patient complains of pain directly under the first metatarsophalangeal joint that is worse with weight-bearing activities. The history may be significant for a trauma to the toe causing a fracture, but most commonly, the pain has an insidious onset.

Manual palpation of the area will reveal which sesamoid is affected, medial or lateral. Also, during the physical examination, postural abnormalities of the foot that may be contributing to the condition are evaluated. For example, hallux valgus deformity may cause a subluxation of the sesamoid from its normal articulation with the plantar aspect of the metatarsal head, causing pain, whereas pes cavus may result in greater pressure under the sesamoids, leading to symptoms.

Imaging Studies

Radiographs of the weight-bearing foot are taken and include a skyline or sesamoid view, which is a tangential view of the sesamoid metatarsal head articulation. On the anteroposterior view, subluxation of the sesamoids lateral to the first metatarsal head can be present with hallux valgus deformities. On the skyline view, fragmentation can be seen in cases with osteonecrosis, and joint space narrowing and osteophyte formation are seen with osteoarthritis. Displaced fractures are easy to determine, but nondisplaced fractures may be difficult to distinguish from a bipartite sesamoid that is a normal finding. A magnetic resonance imaging (MRI) or bone scan may be helpful in the case of normal radiographs to diagnose osteonecrosis or sesamoiditis.

Treatment

Acute injuries involving the sesamoid can be treated with a course of cast immobilization, sometimes non–weight bearing. A toe plate on the cast will provide greater immobilization and support. For chronic problems, a stiff-soled postoperative-type shoe may be used, and a soft felt pad can be placed just proximal to the sesamoids to take the pressure off the involved area. If needed, an orthotic device with a metatarsal pad or bar will relieve sesamoid pressure. Usually the majority of symptoms resolve in a matter of weeks, although some degree of discomfort may persist for several months. If 6–12 months of conservative treatment does not relieve the symptoms, the affected sesamoid can be removed via sesamoidectomy, which relieves the pain. There is the possibility of transferring pain to the remaining sesamoid.

The most common disorders of the lesser toes are mallet toe, hammer toe, and claw toe deformities. Understanding the etiology is important in effective treatment of the deformity. Some of the causes include inflammatory arthritis, trauma, congenital abnormalities, or neuromuscular disorders. There may be anatomic factors, such as a wide foot, a long second ray, or postural abnormalities of the foot. However, the most common etiology is long-standing, ill-fitting shoewear. A narrow toe box with a high heel places abnormal forces on the lesser toes. With chronic wear, deformities may develop. Other disorders are hard and soft corns and metatarsophalangeal joint subluxation or dislocation. Patients may complain of pain and difficulty with shoewear. Importantly, patients with neuropathy may develop ulcerations over the bony prominences of these deformities, such as the proximal interphalangeal joint in a hammer toe or claw toe deformity.

General Considerations

The anatomic structures that stabilize the metatarsophalangeal joint on the plantar aspect are the plantar capsule, plantar aponeurosis (plantar plate), and medial and lateral collateral ligaments. While on the dorsal aspect of the metatarsophalangeal joint, the extensor digitorum longus and brevis tendons and the extensor hood or sling make up the extensor mechanism. The extensor mechanism allows for dorsiflexion of the metatarsophalangeal joint. In addition, this mechanism can extend the distal interphalangeal and proximal interphalangeal joints if the proximal phalanx is in a neutral or plantar-flexed position. On the plantar aspect, the interossei and lumbricals lines of action pass plantarward to the axis of the metatarsophalangeal joint, and thus flex the metatarsophalangeal joint. Also, the flexor digitorum brevis flexes the distal interphalangeal joint, and the flexor digitorum longus muscle flexes the proximal interphalangeal joint. When the metatarsophalangeal joint is hyperextended, the ability of the extensor hood to extend the distal interphalangeal and proximal interphalangeal joints is significantly diminished. Chronic hyperextension of the metatarsophalangeal joint eventually leads to fixed flexion deformities at the interphalangeal joints. A fixed deformity is significantly more symptomatic than a flexible deformity.

Mallet Toe Deformity

A mallet toe is a flexion deformity of the distal interphalangeal joint, and it may be fixed or flexible. In most cases, the second toe is involved, because it is the longest toe.

Clinical Findings

Symptoms and Signs

The patient complains of pain either on the dorsum of the distal interphalangeal joint or on the tip of the toe from striking the ground. The affected area may have a callus. Patients with peripheral neuropathy may present with an ulcer. The nail may develop a deformity with chronic trauma from pressure from the shoe or ground.

Physical examination includes a complete evaluation of both feet, including the neurovascular status. To diagnose a flexible mallet toe, the ankle is brought into plantar flexion. If the deformity corrects and then recurs when the ankle is placed into dorsiflexion, the mallet toe is flexible. However, with a fixed deformity, ankle motion does not affect the deformity.

Imaging Studies

Weight-bearing radiographs of the foot are obtained to show the deformity of the distal interphalangeal joint.

Treatment

Conservative Management

The patient should be educated to wear a shoe with a wide toe box to accommodate the deformed toe. An extra-depth shoe may be needed to decrease pressure on the deformity. A small felt pad may be placed on the shoe liner, just proximal to the deformity, to prevent the tip of the toe from striking the ground.

Surgical Treatment

A flexible mallet toe can be treated by releasing the flexor digitorum longus tendon. This can be accomplished under a digital block, and a small incision on the plantar aspect of the toe at the level of the middle phalanx allows for releasing the flexor tendon. This treatment is usually effective.

With a fixed mallet toe deformity, the toe must be treated with a condylectomy. Under digital or ankle block anesthesia, a dorsal elliptical incision over the distal interphalangeal joint exposes the distal aspect of the middle phalanx. The head and neck of the middle phalanx are removed with a small bone cutter. A 0.045-inch K-wire is used to hold the reduction for 4 weeks (Figure 8–17).

Generally, good resolution of symptoms and deformity results. Persistent deformity or recurrence may occur if contracture of the flexor digitorum longus tendon was not appreciated prior to surgery or insufficient bone was removed from the middle phalanx to decompress the deformity adequately.

Hammer Toe Deformity

A hammer toe is flexion contracture of the proximal interphalangeal joint (ICD-9 735.4), and it may be fixed or flexible. It is frequently associated with varying degrees of hyperextension of the metatarsophalangeal joint, and there may be an associated flexion deformity of the distal interphalangeal joint. Occasionally, the distal interphalangeal joint has an extension deformity.

Clinical Findings

Symptoms and Signs

Like the mallet toe, patients complain of pain and difficulty with shoewear. The pain is localized to the dorsal aspect of the proximal interphalangeal joint or on the plantar aspect of the affected metatarsal head. Physical examination evaluates both lower extremities, noting if the deformity is fixed or flexible. Also, the metatarsophalangeal joints are inspected for joint abnormalities, most commonly hyperextension deformities. Callus formation or even an ulcer may be present over the extensor surface of the proximal interphalangeal joint, where the deformity rubs against the shoe. If the metatarsophalangeal joint is involved, then correction may be needed to fully correct the hammer toe. It is important to evaluate any deformity involving the hallux; a hallux valgus deformity may be part of the cause of a hammer toe deformity. If this is the case, then the hallux valgus deformity requires correction to provide space for the second toe to be reduced into corrected alignment.

Imaging Studies

Weight-bearing radiographs of the foot will reveal arthrosis of the joint. The radiographs will confirm the clinical findings of the proximal interphalangeal flexion deformity, hyperextension deformity at the metatarsophalangeal joint, and hallux valgus deformity. It is important to fully evaluate the entire forefoot and all its joints when planning a procedure.

Treatment

Conservative Management

As with mallet toes, patients may benefit from shoe wear that accommodates the deformity. The shoe should have a wide toe box and may be of extra depth. Over-the-counter toe sleeves and pads can alleviate pain in the affected areas, especially around callosities. With more severe deformities, shoewear becomes more difficult. Hence, nonoperative management becomes more difficult. This is especially true with a severe hallux valgus deformity or claw toe deformity.

Surgical Treatment

The operative procedure to correct the hammer toe deformity depends on whether it is a fixed or flexible deformity. Additionally, deformity of the metatarsophalangeal joint needs to be corrected concomitantly, and finally, the hallux deformity, if present, must be addressed. This will provide a space for the second toe to be placed in correct alignment.

Flexible Hammer Toe Deformity

A flexible hammer toe deformity can be treated with a Girdlestone flexor tendon transfer. A small plantar incision is made to harvest the flexor digitorum longus. The tendon is split in half, and each portion is brought up subcutaneously on each side of the proximal phalanx through a dorsal longitudinal incision. The tendon segments are sutured into the extensor hood mechanism with the toe held in approximately 5 degrees of plantar flexion and the ankle in plantar flexion (Figure 8–18). This causes the long flexor tendon to act as an extensor of the interphalangeal joints and a flexor of the metatarsophalangeal joint, thereby correcting the deformity. A soft dressing is applied, and a postoperative shoe is worn for 4 weeks, after which ambulation is allowed.

Fixed Hammer Toe Deformity

A fixed hammer toe deformity requires a bony procedure to correct the flexion contracture. This is accomplished with the DuVries proximal phalangeal condylectomy (CPT 28285). This procedure is identical to that described for treatment of the mallet toe deformity, but occurs at the proximal interphalangeal joint instead of the distal interphalangeal joint (Figure 8–19). Clinical results show a majority of patients were satisfied and a low risk of recurrence of deformity.

Complications

The main complication observed with either procedure is inadequate correction of the deformity, usually because of failure to appreciate a contracture of the flexor digitorum longus tendon at the time of surgery. In the DuVries condylectomy, inadequate bone may have been resected.

Claw Toe Deformity

A claw toe deformity involves hyperextension of the metatarsophalangeal joint and flexion of the interphalangeal joint. The deformity may be flexible or fixed. Patients complain of pain and difficulty with shoewear. Patients with a neuromuscular disorder frequently will have severe fixed deformities. The pain experienced by patients is over the dorsal aspect of the interphalangeal joints from pressure against the shoe. Also, they have pain on the plantar aspect of the metatarsal heads because the metatarsal heads are forced into plantar flexion from the extended toe. In contrast to hammer toe or mallet toe deformities, which usually involve a single toe, claw toe deformity usually involves all of the lesser toes. An associated deformity of the great toe may occur as well.

Clinical Findings

Symptoms and Signs

Physical examination is performed in a similar manner to mallet and hammer toe deformities. With claw toe deformities, the metatarsal heads are palpated because the fat pad may be displaced distally and the skin beneath the metatarsal heads may be atrophic. Callosities may be present on the extensor surface of the proximal interphalangeal joints and on the plantar aspect of the metatarsophalangeal joints.

Imaging Studies

As previously described, radiographs of the foot confirm the severity of the deformity, which is present at the metatarsophalangeal and interphalangeal joints. The posture of the entire foot needs to be evaluated, looking for the presence of a cavus-type foot deformity, characterized by increased dorsiflexion pitch of the calcaneus and increased plantar flexion of the first metatarsal.

Treatment

Conservative Management

The goal of nonoperative treatment is to decrease the pressure on the claw toe deformities. This is best accomplished with an extra-depth shoe. A custom orthotic device of soft material will help pad the painful metatarsal heads. Flexible mild deformities can be treated with shoe inserts placed immediately proximal to the metatarsophalangeal joints. These can have the effect of balancing the extensors and flexors of the toes.

Surgical Treatment

The operative procedure is determined by the flexibility of the deformity. A flexible claw toe can be treated with the Girdlestone flexor tendon transfer. The extensor tendons must be lengthened to correct the hyperextension of the metatarsophalangeal joints to realign to neutral plantar flexion. Also, a capsulotomy and release of the medial and lateral collateral ligaments may be necessary.

A concomitant fixed hammer toe deformity requires a DuVries proximal phalangeal condylectomy in addition to the Girdlestone tendon transfer procedure. Postoperative management for the patient with claw toe deformity is the same as discussed earlier for hammer toe deformity.

Following this surgical procedure, no active motion of the toes occurs. The toes are usually well aligned in a plantigrade position. The marked deformity of the proximal interphalangeal joints is relieved so they no longer strike the top of the shoe. The main problems that can occur after surgery are (1) failure to correct a fixed hammer toe deformity adequately by use of the tendon transfer and (2) failure to release the fixed deformity adequately at the metatarsophalangeal joint, resulting in recurrence of the deformity.

Hard Corn and Soft Corn (Clavus Durum and Clavus Mollum)

A corn is a keratotic lesion that can develop over a bony prominence on the lesser toes from excessive pressure on the skin such as shoewear (ICD-9 700). A hard corn frequently involves the dorsal and lateral aspect of the fifth toe, over the bony prominence of the lateral condyle of the proximal phalanx, whereas a soft corn presents in the web space, and it is so named because maceration results from moisture between the toes. The soft corn may occur anywhere along the toe where a bony prominence is present, but it is seen mostly in the fourth web space between the base of the proximal phalanx of the fourth toe and the medial condyle of the head of the proximal phalanx of the fifth toe. In a severe case, an ulceration or local infection may occur because of the extent of the maceration.

Treatment

Conservative Management

Decreasing the pressure on the affected toes will help improve symptoms. This can be accomplished with shoewear with a large toe box to relieve this pressure. Local debridement or shaving of the keratotic lesion reduces pain temporarily. This can be performed by the patient; however, it may be difficult in older patients because of decreasing flexibility and poor eyesight. Skin compromise, especially in the diabetic patient, must be avoided. At times, soft pads or lamb's wool can be placed around the toe to minimize pressure on the involved area, but the patient must wear a shoe with an adequate toe box to accommodate such modalities.

Surgical Treatment

Surgical Treatment of the Hard Corn

A hard corn on the fifth toe can be simply treated surgically by excising the distal aspect of the proximal phalanx. Sometimes, the dorsolateral part of the proximal portion of the middle phalanx also needs to be removed. The operation is performed through a longitudinal incision dorsally to avoid a painful scar from chafing against the shoe. The extensor tendon is split, the collateral ligaments cut, and the condyle exposed. With a bone cutter, the distal portion of the proximal phalanx is generously removed and the edges smoothed with a rongeur. Following closure, a compression dressing is applied for several days. The toe is taped to the adjacent fourth toe for 8 weeks, and the patient may ambulate in a postoperative shoe. Long-term results show a high level of patient satisfaction and a low recurrence rate. Removal of excessive bone is the major complication, which causes the small toe to become too floppy, creating a nuisance for the patient.

Surgical Treatment for the Soft Corn

Soft corns are treated surgically by making an incision over the lesion and using a small rongeur to remove the underlying bony excrescence. This is a simple procedure and almost invariably results in satisfactory resolution of the problem.

Syndactyly

Syndactyly is a procedure in which the fourth and fifth toes are connected by removing the web space skin and suturing the two toes together. This will eliminate the problem of a soft corn in the web space. Also, a soft corn can be treated with a condylectomy of the prominent part of the phalanx. This procedure can only be performed if there is no sign of significant maceration, ulceration, or infection. If there is compromise of the skin, then a syndactyly is indicated.

Subluxation and Dislocation of the Metatarsophalangeal Joint

In more severe deformities of the lesser toes, dorsal subluxation or dislocation of the metatarsophalangeal joint may occur. The plantar structures of the plantar plate, collateral ligaments, and plantar capsule become incompetent, and the toe assumes a dorsal position. A hammer toe or mallet toe may be associated with the subluxation or dislocation. Patients complain of pain over the dorsal interphalangeal joint from pressure from shoewear or on the plantar aspect of the metatarsal head. Keratosis can form under the plantar metatarsal head from increased weight-bearing pressure.

General Considerations

The most commonly affected toe is the second, and it is usually associated with a hallux valgus deformity. The pressure of the deformed hallux causes the second toe to sublux or dislocate. Less commonly, a nonspecific synovitis, isolated to the metatarsophalangeal joint and usually involving the second metatarsophalangeal joint, can result in a dislocation. The patient notes some discomfort and swelling around the metatarsophalangeal joint that eventually resolves, usually in 3–6 months. Then an ensuing deformity is noted, with subluxation and possibly dislocation of the joint. Other causes of subluxation and dislocation are direct trauma, rheumatoid or psoriatic arthritis, and neuromuscular disorder.

A somewhat more difficult deformity is a medially or laterally deviated toe. The most common toe is the second because of its prevalence with hallux valgus deformities. With the bunion pressing on the second toe, it can sublux or dislocate and then deviate medially. This deformity may be the result of a steroid injection into the joint. With such a deformity, shoewear is problematic. Patients must wear sandals or an extra-depth shoe to accommodate the deformity.

Clinical Findings

Symptoms and Signs

Patients present with complaints of pain, deformity, and difficulty with shoewear. Swelling may be present. The pain is directly at the joint, on the plantar aspect of the metatarsal head, or over the dorsal aspect of the interphalangeal joint. On examination, the patient is evaluated with the patient in a standing and sitting position. The affected metatarsophalangeal joint is palpated for active synovitis, flexibility of the joint, and degree of subluxation. An anterior drawer test is performed on the affected joint to determine its stability. This is performed by holding the proximal phalanx between the examiner's fingers and moving it dorsally and plantarward, similar to a Lachman test of the knee. Also, the hallux is noted for any deformity, namely a hallux valgus deformity, as this is frequently associated with crossover of the second toe on the first toe.

Imaging Studies

Weight-bearing foot radiographs allow for evaluation of the severity of the subluxation or frank dislocation. Also, the hallux valgus deformity is evaluated, and changes about the articular surface of the joint are observed. Patients with rheumatoid arthritis usually have multiple joint abnormalities.

Treatment

Conservative Management

Patient education is an important first step to conservative management. A wide toe box shoe to accommodate the patient's deformity is often helpful. If needed, a total contact soft orthotic device will relieve pressure on the metatarsal head. The shoewear may need to be adjusted to accommodate an insert. For nonspecific synovitis, a cortisone injection may be beneficial; however, only three injections are given, and at least 1 month is allowed between injections. If the patient cannot be accommodated adequately with these modalities, surgical intervention may be indicated. A significant hallux valgus deformity indicates the need for correction to make a space for second toe correction. Failure to treat both problems results in recurrence.

Surgical Treatment

The subluxed metatarsophalangeal joint with a flexible hammer toe is treated by releasing the dorsal contracture of the extensor tendons, joint capsule, and collateral ligaments. A Girdlestone flexor tendon transfer, as previously described, will maintain the correction. Also, tenodesis of the plantar plate may be a treatment option. If a fixed hammer toe is present, a proximal phalanx condylectomy is added to the procedure. A dislocation of the metatarsophalangeal joint is a more severe deformity and requires some bony element. The soft tissues, including the extensor tendons, joint capsule, and collateral ligaments, are incised. In addition, a synovectomy of the metatarsophalangeal joint is performed, and finally, the distal third of the metatarsal head is excised to allow reduction of the joint. Accompanying hammer toe procedures are performed to correct the invariably present fixed hammer toe.

A 0.062-inch K-wire is used to stabilize the correction for 4–6 weeks. After pin removal, the toe is taped for several weeks. This procedure results in significant joint stiffness and possible resubluxation of the joint.

For severe deformities such as dislocation of the metatarsophalangeal joint, a bony procedure is added. This is achieved with an osteotomy at the level of the metatarsal neck (CPT 28308). The osteotomy is performed through a hockey stick incision over the dorsal joint, and the saw blade is placed at the dorsal aspect of the metatarsal head and aimed proximally. The saw blade is kept parallel to the plantar aspect of the foot to result in a long oblique osteotomy. A 1-mm saw blade is used for most osteotomies. A thicker saw blade, 2 mm, is used when more than 5 mm of shortening is required or with a plantar inclination of less than 19 degrees. Once the osteotomy is complete, the metatarsal head is allowed to slide proximally to the appropriate level that will allow the joint to reduce. The amount of shortening is usually between 4.0 and 6.0 mm. The osteotomy is fixed with a single 2.5-mm or smaller diameter cortical screw.

If necessary, a hammer toe procedure may be added to fully correct the deformity. Good to excellent results have been reported, but there is limited follow-up and number of cases. There can be reduction in pain, improvement of function, and resolution of intractable plantar keratosis, without the complication of joint stiffness as occurs with the previously described procedures. Complications from this procedure are stiffness, redislocation, plantar penetrating hardware, and floating-toe deformity (extension contracture of the metatarsophalangeal joint causing the toe not to touch the ground).

A crossover toe is difficult to treat. Generally, the deformity is more severe, and radiographs show a dislocated second or third metatarsophalangeal joint with medial or lateral deviation. The operative treatment realigns the toe with soft-tissue release of the contracted tendons and ligaments medially or laterally, depending on the deformity. For more severe deformities, a bony procedure is added. This can be accomplished with a closing-wedge osteotomy at the base of the proximal phalanx or an oblique distal metatarsal osteotomy, previously described for treatment of dorsally subluxated metatarsophalangeal joints. The technique is identical, but some soft-tissue balancing may need to be added to the procedure to correct the medial/lateral deviation.

Regional anesthesia is an important component of foot and ankle surgery because most procedures are performed in the outpatient setting. The nerve block can be administered by the surgeon. Many operations distal to the ankle can be performed without general anesthesia, which can eliminate the possible complications of central nervous system depression. In addition, the postoperative opioid requirements are significantly reduced.

Digital Block

Indications

A digital block is ideal for operations involving the toes. These may include procedures for nail disorders, correction of hammer toe or mallet toe, tendon releases, and some metatarsophalangeal joint procedures.

Technique

Short- and longer-term anesthesia is provided by digital block using a 1:1 mixture of 1% lidocaine hydrochloride and 0.25% bupivacaine. A short 25-gauge needle is used to inject approximately 1.5 mL on either side of the toe within the subcutaneous layer between the skin and deeper fascia. The needle is then passed toward the plantar aspect of the toe to anesthetize the digital nerves. Both sides of the toe should be anesthetized. Anesthesia should be administered before the operative site is prepared to allow the approximately 15 minutes necessary for the block to take effect before starting a procedure.

Ankle Block

Indications

Ankle block anesthesia is useful for forefoot and midfoot procedures. These can include bunionectomies, neuroma excision, metatarsal osteotomies, and tarsometatarsal arthrodeses. Also, ankle block anesthesia is preferred to multiple digital blocks for ipsilateral multiple toe procedures. Ankle block anesthesia is appropriate for more proximal procedures, such as hindfoot arthrodesis or ankle arthroscopy.

Technique

An ankle block anesthetizes the posterior tibial nerve, superficial branch of the deep peroneal nerve, sural nerve, saphenous nerve, and superficial peroneal nerve. The posterior tibial nerve requires a larger 3-cm, 22- or 25-gauge needle and approximately 7–10 mL of a 1:1 mixture of 1% lidocaine hydrochloride and 0.25% bupivacaine. The landmark for the posterior tibial nerve behind the malleolus is approximately two finger breadths proximal to the tip of the malleolus and along the medial border of the Achilles tendon (Figure 8–20). The needle is inserted perpendicular to the shaft of the tibia until the posterior cortex of the tibia is palpated with the tip of the needle. The needle is then withdrawn approximately 2 mm. Approximately 5 mL of anesthetic agent is injected into this area after aspiration is done to confirm that the needle is not in a vessel. The deep peroneal nerve is injected at the level of the navicular. The extensor hallucis and extensor digitorum longus tendons are palpated at this site, and the deep peroneal nerve is just lateral to the dorsalis pedis artery. The 25-gauge needle is inserted and advanced to bone and then withdrawn 1–2 mm, aspiration is attempted, and approximately 5 mL of anesthetic is injected. The saphenous nerve is identified one to two finger breadths proximal to the tip of the medial malleolus and just posterior to the saphenous vein. A 25-gauge needle is inserted and 5 mL of anesthetic injected. The sural nerve is blocked approximately 1–1.5 cm distal to the tip of the lateral malleolus and can often be palpated in the subcutaneous fat. A 25-gauge needle is inserted and approximately 5 mL of anesthetic injected. The superficial peroneal nerve branches are blocked starting two finger breadths proximal and anterior to the tip of the lateral malleolus, and the injection is carried out below the subcutaneous veins but above the long extensor tendons in a ring-type block. Approximately 5 mL of anesthetic agent is used. The anesthesia for ankle block takes effect within 15–20 minutes.

Popliteal Block

Indications

The popliteal block can be used for most major foot or ankle procedures. These include ankle arthrodesis, hindfoot arthrodesis, calcaneal osteotomy, tarsometatarsal arthrodesis, posterior tibial tendon reconstruction, and surgical treatment of calcaneal or ankle fractures. The nerve block can be used with general anesthesia, sedation, or as the sole anesthetic technique. If a thigh tourniquet is required, then a general anesthetic may be added. The popliteal nerve block has low morbidity, high success rate, long analgesia, and can be administered by the orthopedic surgeon.

Technique

The patient is placed in the lateral decubitus position with a pillow between the knees. The landmarks to block the tibial nerve in the popliteal fossa are the lateral and medial epicondyles of the femur and the medial and lateral belly of the gastrocnemius. The puncture site is at the idle of the line connecting the epicondyles (Figure 8–21) where the nerve stimulator set at 1.2 mA is inserted vertically to locate the tibial nerve. At a penetration depth of 2–3 cm, a contraction is found, and the needle is advanced until plantar flexion and inversion occurs. The output of the stimulator is decreased gradually to 0.5 mA. Following aspiration, a test dose of 1 cc is placed of 0.5% bupivacaine. The test dose should cause a pause of muscle contraction, and the remaining 29 cc of 0.5% bupivacaine is injected with intermittent aspiration. The peroneal nerve is located at the head of the fibula and the neurostimulator with an output of 1.2 mA, causing dorsiflexion and eversion of the foot. The output is reduced to 0.5 mA to confirm the proximity of the nerve, and 3–5 cc of bupivacaine is injected. Finally, the saphenous nerve is located at the level of the tibial tubercle. The area infiltrated is between the tibial tubercle and the proximal gastrocnemius muscle. Approximately 3–5 mL of 0.5% bupivacaine is used.

Alternatively, a perineural catheter can give up to 72 hours of postoperative pain relief compared to 13–16 hours with a single-shot popliteal block. The block can be performed with the patient supine. The stimulating needle is placed anterior to the biceps femoris tendon at the superior pole of the patella level, angling 45 degrees (Figure 8–22). The nerve stimulator is used to confirm placement, and a test dose of 1 cc of anesthetic is placed. Then a standard block of 20 cc of 0.5% bupivacaine is placed. The catheter is connected to a pain pump to infuse the local anesthetic dose depending on the patient's weight. The pain pump begins infusion at 6 hours postoperatively and then is removed by a visiting nurse at 72 hours. Another method for the sciatic popliteal block is with localization with ultrasound guidance, with the needle insertion at the separation of the tibial nerve and common peroneal nerve.

Metatarsalgia is a general term for pain arising from the metatarsal head region. The center of pressure during normal gait is initially applied to the heel and progresses along the plantar aspect of the foot. For more than 50% of the stance time, the pressure is concentrated beneath the metatarsal head area. This extended period of pressure can cause bothersome pain. A precise diagnosis is necessary in metatarsalgia to direct treatment toward the specific cause.

Etiologic Findings

Metatarsalgia encompasses a broad spectrum of conditions with various causes arising out of the anatomic structures in the area. It may be associated with abnormalities of the metatarsal head subluxation or dislocation of the metatarsophalangeal joints, systemic diseases, dermatologic lesions, soft-tissue disorders, or iatrogenic causes. Table 8–1 lists the various causes of metatarsalgia and the differential diagnoses that should be considered in evaluating these patients.

Clinical Findings

Symptoms and Signs

The clinical evaluation begins with a careful history directed toward delineating the precise location of the pain. The physical examination of the foot and lower extremity begins with the patient standing. Any deformities of the toes are noted, such as clawing of the toes, a long second ray, or swelling around any of the joints. The patient should be evaluated for a postural problem of the foot, such as a flat foot or cavus foot. The plantar aspect of the foot is carefully evaluated for evidence of callus formation. The metatarsal heads are palpated individually to assess for generalized plantar fat pad atrophy, a prominent fibular condyle, synovitis, or possibly a transfer lesion beneath a metatarsal head resulting from previous forefoot surgery.

Imaging Studies

The radiographic evaluation includes weight-bearing anteroposterior, lateral, and oblique views of the foot. Occasionally, the so-called skyline view of the metatarsal heads (obtained with the metatarsophalangeal joints in dorsiflexion) is helpful to evaluate their overall alignment, particularly in cases resulting from previous surgery, by demonstrating the height of the metatarsal heads. MRI can be useful in the diagnosis of metatarsalgia, such as distinguishing among a neuroma, cyst, bursa, or synovitis.

Treatment

Conservative Management

Conservative management is directed at relieving the pressure beneath the area of maximum pain. Initially, the patient must obtain a shoe of appropriate style and adequate size to allow an orthotic device to be inserted. A lace-type shoe with a soft sole material and an adequate toe box is appropriate. High-heeled shoes, loafers, or tight shoes are inappropriate because they have decreased volume for the foot and may cause increased pressure against the involved area. As a general rule, the softer the orthotic device, the more comfortable is the patient. A hard acrylic orthotic device is not particularly comfortable for the patient and should usually be avoided.

Surgical Treatment

The surgical management of metatarsalgia depends on the cause and is discussed in different sections of this chapter. In general, pain from a bony prominence can be relieved by a partial ostectomy or osteotomy, dermatologic lesions such as warts can often be burned off with liquid nitrogen or excised, or pain caused by a subluxated metatarsophalangeal joint can be corrected with tendon transfer. The outcome depends on the severity of the problem and the type of surgical intervention required for correction.

Keratotic disorders of the foot usually manifest in plantar callosities and are also called intractable plantar keratosis (ICD-9 700). These occur as a result of friction and increased pressure over bony prominences. Some plantar callosity is normal, but if it becomes excessive, it can be painful and disabling.

General Considerations

Many of the intractable plantar keratoses arise from the bony abnormalities of the forefoot. These abnormalities are listed in Table 8–1.

Clinical Findings

Symptoms and Signs

The patient's history will reveal the affected area on the foot and the severity of pain. In addition, the past medical history is important, as past operations and medical disorders may be part of the etiology. The patient's work, type of activities, shoewear, how often the callus needs to be trimmed, and the type of orthotic devices used are all important in a complete history. The physical examination, however, is the most important single factor in the diagnosis of intractable plantar keratoses. First, the overall posture of the foot needs to be evaluated to determine whether the condition is the result of a postural abnormality. This is accomplished with the patient undressed from both knees down and standing. Findings can involve a rigid plantar-flexed first metatarsal that could cause a diffuse callus beneath the first metatarsal head, or a hypermobile first ray that fails to support the medial forefoot may result in generalized callus formation beneath the second and third metatarsal heads. Another type of deformity is a varus posture of the forefoot (the lateral aspect of the foot in greater plantar flexion than the medial aspect), which may result in callus formation beneath the fifth metatarsal head. Also, note the type of callus. A diffuse callus is usually associated with a long metatarsal. The callus may have arisen after trauma or surgery in which an adjacent metatarsal was dorsiflexed, thereby increasing the weight-bearing load of the metatarsal. In contrast, a distinct well-localized lesion beneath the metatarsal head is often caused by a prominent fibular condyle of the metatarsal head of the second or third metatarsal. A callus on the bottom of the foot must be differentiated from a plantar wart, which can occasionally mimic a plantar callosity. Shaving the lesion reveals bleeding from end arteries in a plantar wart, whereas a keratotic lesion consists only of hyperkeratotic tissue.

Imaging Studies

Weight-bearing anteroposterior, oblique, and lateral radiographs of the foot will generally reveal abnormalities seen clinically. These include hallux valgus, hammer toe, claw toe, and varus deformity.

Treatment

Conservative Management

Debridement or trimming of the intractable plantar keratosis can provide some relief, albeit temporary. Directing the treatment to the underlying deformity will bring long-term benefit. This can be achieved by decreasing the direct pressure or friction from the callosities. A shoe that is made of soft material and accommodates the size and shape of the foot will provide some relief of pain and disability. This usually involves a lace-up type shoe with adequate padding. Inexpensive padding and soft inserts can be found over the counter and will benefit many patients. With some patients and deformities, however, a total contact orthotic device can be effective (Figure 8–23). It is usually made of soft material and redistributes the weight bearing from bony prominences that cause the callosities.

Surgical Treatment

Operative procedures for intractable plantar keratoses are determined by the underlying deformity. One of the most common problems is a prominent fibular condyle of the metatarsal head. It occurs most frequently underneath the second metatarsal but may also be found underneath the third and fourth metatarsals. The prominence is approached through a dorsal hockey stick incision over the metatarsophalangeal joint, and the toe is plantar flexed to expose the plantar aspect of the metatarsal head (CPT 28288). An osteotome is used to excise 30% of the plantar condyle of the metatarsal head, thereby removing the sharp bony prominence (Figure 8–24). This procedure results in predictable pain relief of the affected toe, although 5–10% of patients develop a transfer lesion beneath the adjacent metatarsal head.

A diffuse callus beneath the second metatarsal that is the result of a dorsiflexed or hypermobile first metatarsal can be treated with dorsiflexion osteotomy done at the base of the second metatarsal. If the lesion is the result of an excessively long metatarsal, it may be shortened to the level of a line drawn between the adjacent metatarsal heads, thereby reestablishing a smooth metatarsal pattern. If the callus is a result of a dislocated metatarsophalangeal joint, such as in a claw toe deformity, the joint must be reduced, using one of the techniques previously described. Correction of the joint alignment will decrease the plantar against the metatarsal head. All of these surgical procedures to eliminate a callus are fairly successful, although the possibility of a transfer lesion developing is approximately 5–10%.

The tibial sesamoid can be prominent and an underlying callosity can form. This is treated through a medial approach, and the plantar third of the sesamoid is shaved down. This alleviates the callus in almost all cases, with the only significant complication being caused by inadvertent disruption of the plantar medial cutaneous nerve during the surgical approach to the sesamoid.

Keratoses can occur about the fifth metatarsal head. If it occurs on the lateral aspect of the forefoot, the deformity may be a bunionette, also called tailor's bunion. A diffuse callus beneath the fifth metatarsal head can be treated with a midshaft metatarsal osteotomy to bring it out of its plantar-flexed position, which usually alleviates the condition. It is unusual for a transfer lesion to occur beneath the fourth metatarsal head. If the bony prominence is on the lateral aspect of the foot rather than the plantar aspect, then an osteotomy of the fifth metatarsal head will correct the deformity. A chevron type osteotomy can be made and the head is translated medially (Figure 8–25).

Finally, a subhallux sesamoid can cause a small callus on the plantar aspect of the interphalangeal joint of the great toe. Treatment is simply surgical excision of the sesamoid, and good results can be expected with little or no disability.

Approximately 22 million people in the United States are diabetic, and foot problems are the most common cause for hospitalization, accounting for 20% or more of all inpatient days in this population. More than half of all nontraumatic amputations are performed on diabetics. One report showed a 68% incidence of foot disorders in a large diabetic clinic, and the cost of care of these problems approaches $100 million per year. Treatment of the diabetic who presents with foot problems can be complex and require a team approach, involving the primary care physician, vascular surgeon, orthopedic surgeon, infectious disease specialist, orthotist, diabetic nurse specialist, and, whenever possible, the patient's family members.

Pathophysiologic Findings

Diabetes is a metabolic disorder that involves all the organ systems. Those of primary interest to the orthopedist are integumentary with the risk of ulceration, neurologic with the loss of protective sensation, vascular with diminished perfusion, and immunologic with limited ability to fight infection. The most frequent problem faced by the diabetic is breakdown of the skin of the foot (Figure 8–26). The cause of foot ulcers is multifactorial but stems from diminished sensation resulting from neuropathic disease. Unappreciated local stresses are placed on the skin externally by poorly fitting shoes and internally by skeletal deformity. Autonomic neuropathy causes dry skin and cracks in the dermis, which may become portals of entry for infection. Reactive hyperemia, which normally helps to clear infections, is blunted by autonomic neuropathy. Motor neuropathy affects the intrinsic muscles of the foot and may lead to claw toe deformities with metatarsal heads and proximal interphalangeal joints becoming prominent and predisposed to ulcerations. Hyperglycemia can impair wound healing strength as well as damage vascular endothelium, which is a precursor to atherosclerosis and leads to diminished extremity blood flow and limited healing potential. Elevated blood glucose levels over a long period also lead to glycation of the body's proteins and is commonly measured by hemoglobin A1c. Glucose covalently binds to lysine in proteins in a reversible process. It is felt that the addition of glucose molecules changes the flexibility of tissues, especially fibrous tissue, making tissues such as skin less able to handle sheer stresses. The neuropathy in diabetics is due to the loss of myelinated and unmyelinated nerve fibers. Other factors that affect healing in diabetics include nutritional deficiencies, diminished ability to protect oneself due to diabetic encephalopathy and diminished cognition, and lowered resistance to infection.

History

When a diabetic patient presents to an orthopedist, there are four areas of impact: ulcers and their prevention, amputations, Charcot arthropathy, and toenail abnormalities. With an infected foot ulceration, it is essential to obtain a history that will help delineate why the ulcer occurred and how to optimize the patient's healing potential. A past history of foot surgery is sought, previous or current antibiotic usage is detailed, and any recent trauma to the foot is noted. A history is taken about the severity of the patient's diabetes, including how long ago the diabetes was diagnosed, whether the patient is taking insulin, their recent level of control, what other organ systems are involved, and the degree of neuropathy that is present in the patient's feet.

Clinical Findings

General Examination

Examination of the diabetic patient should begin with inspection of the shoe for internal and external wear patterns. The leg and foot are inspected for overall appearance of the skin, hair growth, perfusion, pulses, and color.

Foot Examination

Any bony prominences are recognized as areas of potential skin breakdown. The most common prominences are located at the apex of deformities such as under the metatarsal heads, on the dorsum of the proximal interphalangeal joints, under the medial sesamoid, at the base of the fifth metatarsal, under the medial arch in the Charcot foot, and over the medial eminence of the hallux. Neurologic examination should test for the presence of protective sensation, as defined by the patient's ability to feel the 10-g Semmes-Weinstein monofilament as well as motor function. Ulcers should be carefully documented and evaluated for evidence of infection in the adjacent soft tissues. Wounds should be measured for length, width, and depth, in addition to documenting their location. Open wounds should be probed with a sterile Q-tip or other appropriate instrument to evaluate the extent of involvement of deeper structures, such as tendons, joints, and bone. A positive probe to bone test usually indicates the presence of osteomyelitis.

Vascular Findings

Vascular evaluation is essential to ensure that the patient has adequate perfusion to allow healing. Patients with palpable pedal pulses and normal capillary filling have adequate blood supply and usually do not require further vascular evaluation. For patients with less perfusion, one method of assessing the overall potential for healing of foot lesions in a diabetic is the ischemic index. This index is obtained by dividing the blood pressure measurement in the brachial artery by that in the dorsalis pedis and posterior tibial arteries, as measured by Doppler ultrasound with a calf cuff. If the index is 0.45 or greater, there is a 90% chance that a foot ulcer will heal. Lower indices are an indication for a vascular surgery consultation. It must be kept in mind, however, that falsely elevated values of blood pressure in the foot may result from calcification of major blood vessels. Thus, apparent vascular insufficiency in the light of an adequate ischemic index also warrants a vascular surgery consultation. A laser Doppler study can also be beneficial in assessing local skin perfusion. This information can be used to help predict the patient's response to surgical intervention.

Imaging Studies

Radiographic studies should include weight-bearing radiographs of both feet and ankles as indicated. Plain radiographs can help identify bony prominences that predispose the patient to ulcer formation, and osteomyelitis or changes consistent with a neuropathic foot may be identified. Early Charcot (neuropathic) joint changes may be difficult to differentiate from osteomyelitis. The four D's of neuropathic joints are helpful in delineating more advanced cases: debris, destruction, dislocation, and densification.

The presence of bony infection may be delineated on serial radiographs as progressive osteolysis, realizing that changes on plain films are late findings and suggesting that the infection has been present for weeks. A technetium bone scan is sensitive in detecting early osteomyelitis but is quite nonspecific. MRI can demonstrate bone and soft-tissue changes, such as edema or the extent of an abscess cavity, and can be helpful distinguishing Charcot changes from osteomyelitis. The recent addition of ring positron emission tomography (PET) scans is more effective in differentiating osteomyelitis from Charcot changes.

Classification and Treatment of Diabetic Foot Ulcers

The Rancho Los Amigos Hospital classification of diabetic foot ulcers is based on the depth of tissue affected and extent of the foot involved. Treatment choice depends on the grade of ulcer (Figure 8–27). Table 8–2 shows treatment based on classification of foot ulcers.

As a general rule in treating infections of the foot, a balance must be struck between salvage of tissue and foot function. A healed amputation at a more proximal level is more advantageous to the patient than leaving a marginally viable area of the foot that requires constant wound care.

Large wounds heal slowly with the risk of secondary infection and, if possible, should not be left to heal by secondary intention. Split-thickness skin grafts, especially on the sole of the foot or over an amputation site, are prone to breakdown.

Surgical Treatment for Relieving Bony Prominences

As previously stated, a major goal of treatment in the ulcerated or “at risk” foot is to relieve bony prominences that cause pressure on the skin. Treatment consists of measures to relieve the pressure. There are many appropriate measures to relieve pressure on the skin from the outside. Examples include extra-depth shoes for claw toes and accommodative foot orthoses with metatarsal pads to relieve pressure under a prominent metatarsal head. If these measures fail or are inappropriate, the pressure should be relieved from the inside by correcting the bony deformity. These prominences are located at several common sites.

The hallux may have a prominence beneath the metatarsal head, on the plantar-medial aspect of the interphalangeal joint, or over the median eminence secondary to a bunion deformity. A prominence caused by the medial sesamoid can be relieved by complete or partial removal of the sesamoid. If this does not adequately relieve the prominence, a dorsiflexion osteotomy or resection of the metatarsal head can be performed. Ulcers found over the plantar-medial aspect of the interphalangeal joint can often be relieved by simple excision of the prominent medial condyles or by resection of the entire joint. If this ulcer is associated with limited metatarsophalangeal extension, then a cheilectomy or metatarsophalangeal arthroplasty may be appropriate to allow the toe to extend further during the toe-off phase of gait and thus decrease the pressure on the skin under the interphalangeal joint. A prominence over the median eminence can be addressed with a routine bunion procedure.

The diabetic patient is subject to claw toe deformities resulting from motor neuropathy, causing prominences under the metatarsal heads and over the dorsum of the proximal interphalangeal joints. Depending on the severity, treatment varies from reduction of the metatarsophalangeal joints and proximal interphalangeal arthroplasties to resection of the metatarsal heads and interphalangeal fusions.

A collapsed longitudinal arch from Charcot changes causes the classic rocker-bottom foot with prominences along the plantar and medial aspects of the midfoot. This can be addressed with a simple exostectomy for a mild deformity that is stable, or an appropriate osteotomy and arthrodesis for a more complex deformity or when there is progressive instability.

Treatment of Osteomyelitis

Osteomyelitis is a common complication present in a grade 3 diabetic foot ulcer. The infection is seldom eradicated without surgical debridement of the bone. Frequently, more radical treatment than simple exostectomy is required. For example, infection of a proximal phalanx is usually treated by resection of the phalanx. Osteomyelitis of the metatarsal may require ray amputation if more than just the head is involved. If multiple metatarsals are infected, a transmetatarsal amputation is often the best treatment with the reminder to always consider lengthening the tendoachilles to decrease load on the residual forefoot.

Osteomyelitis of the midfoot is often a complication of a collapsed Charcot foot. The treatment options for such an infection include wide local debridement with exostectomy or a more proximal amputation. Similarly, osteomyelitis of the calcaneus can be treated with a partial calcanectomy or a more proximal amputation.

Treatment of ulcers should make sense. A patient with a superficial wound with good blood supply, minimal infection, and protective sensation would be treated with topical wound care, a shoe to accommodate the dressing, and limited activity to control swelling. A patient with an infected deep wound with osteomyelitis and nonreconstructable dysvascularity would probably be best served with early amputation. Of course, each patient is unique and deserves an evaluation of all organ systems to develop an appropriate treatment plan.

Wound dressings should try to mimic skin. They should try to provide a healing environment that is bacteria free, warm, moist, strain free, nontoxic, and well oxygenated. There is nothing that will provide all of these. Dressings should be chosen based on the needs of the wound, possibly needing infection control and debridement in the initial phases but later only requiring protection and absorption of wound drainage. The gold standard for treating plantar ulcers is a total contact or healing cast. This protective cast provides wound protection, edema control, and a moist environment, and has been shown to decrease plantar loading to the ulcer. When the wound is draining, they do require frequent changing or the odor can be intolerable.

Biologic wound healing products that provide wound healing factors can be helpful in the patient with marginal healing potential. Larger wounds, especially those with considerable drainage, can benefit from vacuum-assisted closure where a constant negative suction pressure is applied to a sealed wound, thereby decreasing its size and pulling away wound drainage.

There are a small number of patients who are marginal wound healers who will benefit from hyperbaric oxygen treatment. When placed at two atmospheres of pure oxygen, the serum becomes supersaturated and has been shown to benefit some patients who receive serial treatments.

Charcot Foot

A Charcot joint is also referred to as a neuropathic, neurotrophic, or neuroarthropathic joint. Diabetes is by far the leading cause of Charcot joints. A Charcot foot is characterized by destruction of joint surfaces, fractures often accompanied by dislocations of one or more joints in a patient with inappropriate pain response. The requirements are an active patient who has neuropathy and adequate blood supply. The pathophysiology is not fully understood, but there are two theories. The neurotraumatic theory says that cumulative mechanical strains in a patient with inadequate sensory protection leads to stress fractures that are progressive because the patient does not have adequate sensory feedback to limit their activity. The neurovascular theory suggests that there is a neurally initiated vascular reflex that leads to juxtaarticular osteopenia weakening the bone in this area while glycation of the joint capsule causes stiffness. These factors, when combined with mechanical stress, can lead to the fracture dislocations that are commonly seen. There are probably elements of both of these theories that are contributing to Charcot arthropathy.

There are three stages in Charcot arthropathy as defined by Eichenholtz. Stage 1 is the acute inflammatory phase where there is swelling, redness, and increased warmth. Radiographs would likely show fractures and dislocations, and the involved area would be unstable. The concern in this stage would be to rule out infection. If the patient is neuropathic with good blood supply and has an acute, red, hot, swollen foot without an ulcer or a history of an ulcer in that area, it is probably Charcot arthropathy and not infection. Hematogenous osteomyelitis is very rare, and infections in the foot are usually introduced locally through the skin. Stage 2 is the subacute phase where there are signs of healing, less swelling and warmth, and radiographic signs of new bone formation. Stage 3 is the chronic phase with consolidation and resolution of inflammation. Typical locations include the midfoot, with the creation of the rocker-bottom foot deformity as the arch collapses, and the hindfoot and the ankle, with the risk of collapse into varus or valgus that can lead to pressure ulcerization.

Principles of Treatment

There are several important principles to follow in the treatment of Charcot joints. The primary goal is to limit joint destruction and preserve a stable plantigrade foot that will protect the soft tissues and prevent ulceration.

Treatment of Acute Phase

For a patient who presents in the acute phase of Charcot joint, the initial treatment should be immobilization and elevation of the foot. This can best be achieved with a non–weight-bearing total contact cast for patients who can be placed in a plantigrade position. The skin must be checked at weekly intervals initially to look for breakdown. Surgery is rarely attempted on the acute Charcot foot, unless necessitated by the inability to obtain a stable plantigrade position. Even in patients who will require acute stabilization to obtain a plantigrade foot, it is best to allow the swelling and inflammation to diminish by offloading and immobilization prior to surgical intervention. Once the acute phase subsides and the fractures heal, immobilization can be accomplished by means of an ankle-foot orthosis or other appropriate removable support. Custom-made shoes can then be fitted to accommodate for the bony prominences.

Treatment of Subacute Phase

In this phase, the foot has stabilized, and there is no ongoing bony destruction. Operations address the bony prominences that have been created by Charcot destruction and collapse. Often, simple removal of a prominence is all that is required, and sometimes, fusion of one or several joints is necessary. One of the most common foot deformities is a collapsed arch and rocker-bottom deformity from subluxation of multiple joints in the midfoot. Usually, an exostectomy of the prominent bones on the plantar aspect of the midfoot is sufficient. Alternatively, an osteotomy and arthrodesis of the midfoot can be performed to realign the foot and reconstitute the arch in cases where a simple exostectomy is inadequate (Figure 8–28). There is usually a contracture of the ankle plantar flexors, and this deforming force may need to be released as part of this procedure. This procedure has a high complication rate and an extended time to achieve union. In the case of Charcot involvement of the ankle joint, the goal is a stable and plantigrade foot, which often requires arthrodesis. Retrograde intramedullary nailing has been shown to be successful in achieving union but also has significant complication rates.

Toenail problems, in younger diabetics, usually involve trauma, such as stubbing the toe or, more frequently, improper nail care, which can contribute to ingrown toenails. This is usually the result of tearing off a toenail, which leaves the nail too short and predisposes it to become ingrown.

Toenail problems in the older age group are more varied, including an incurvating nail, a thickened hypertrophied nail associated with a chronic fungal infection, an ingrown nail resulting from improper nail cutting, and on rare occasions, a subungual exostosis.

Etiologic Findings

The anatomy of the toenail is demonstrated in Figure 8–29. The nail unit consists of four components: the proximal nail fold, the nail matrix, the nail bed, and the hyponychium. The area in which most of the problems occur is the lateral or medial nail groove, where an ingrown nail occurs at the level of the nail bed or hyponychium.

Clinical Findings

Symptoms and Signs

The history of most nail problems is not complex and usually quickly defines the nature of the problem.

Infection of the Toenails

Infection of the toenails usually begins slowly, with erythema and swelling along the margin of the nail, followed by increasing pain and drainage, and finally the development of granulation tissue, usually in response to the foreign body reaction to the nail itself.

Mycotic Nail

In the case of the mycotic (fungal) nail, there is usually a long, slow history of development of deformation of the nail, often with medial or lateral deviation of the nail, marked hypertrophy, and increased pain when wearing shoes. At times, an incurvated nail condition develops in which one or both edges of the nail slowly curve inward, resulting in pinching of the nail plate. This may cause a localized infection, or it may be that just the sheer pressure of the nail against the skin is the cause of the pain.

Subungual Exostosis

The patient who develops subungual exostosis usually notes pain evolving beneath the toenail over a long period. Erosion of the nail from below occurs because of the pressure of the exostosis against the nail itself. Often, the patient does not seek help until there is actual breakdown of the tissue, giving rise to a rather ugly appearing lesion that seems much more ominous than the condition itself.

Imaging Studies

Radiographs are necessary when evaluating a toenail problem for subungual exostosis, which is clearly seen with a lateral view. In patients with long-standing infected ingrown toenails, a radiograph can be important to rule out underlying osteomyelitis.

Treatment

Conservative Management

Chronic Ingrown Toenail

For the chronic ingrown toenail, the margin of the nail is removed to relieve the pressure of the nail against the skin. This procedure, along with local care and occasionally systemic antibiotics, usually permits the condition to resolve. It is important, however, to explain to the patient the necessity of permitting the nail to grow out over the ungual labia to depress it and prevent the ingrown nail from recurring.

Chronic Onychophosis of the Nail

Chronic onychophosis of the nail must be kept debrided. If an ingrown nail occurs, the margins must be trimmed to relieve the pressure against the skin.

Subungual Exostosis

Subungual exostosis that is symptomatic is treated by excision.

Surgical Treatment

Ingrown Toenail

The surgical management of the recurrent ingrown toenail consists of the Winograd procedure. In this procedure, the medial or lateral margin of the offending nail plate is removed along with the underlying nail matrix. The nail matrix is removed as thoroughly as possible to prevent the possible growth of a nail horn, which occurs in about 5% of cases. The nail matrix can be removed by sharp dissection or ablated with a laser or treated with phenol to kill the nail matrix.

Chronic Infection

If there is severe distortion of the nail caused by chronic infection, the nail and the nail bed can be removed in their entirety. This usually results in a horny base where the nail existed, and this is often a satisfactory outcome. The terminal Syme amputation can be carried out to eliminate the nail and matrix completely (Figure 8–30). Although results are usually satisfactory, some patients do not like the appearance of the toe or absence of the toenail because of its somewhat bulbous appearance. The terminal Syme procedure can be carried out under digital block in most patients. An elliptical incision is made over the distal end of the toe, removing the nail and its matrix in their entirety. The distal portion of the distal phalanx is removed and the edges smoothed, thus shortening the toe. The tip of the toe is defatted and loosely sutured. In this manner, the nail is completely removed, and soft tissue covers the area of the former nail bed. The only significant complication associated with this procedure is the regrowth of some nail matrix beneath the healed flap, which will result in an inclusion cyst that must be drained and the residual nail matrix excised.

Subungual Exostosis

Surgical management of subungual exostosis requires lifting the nail, identification of the exostosis, and complete removal of the exostosis and its stalk. The dissection must be carefully carried out and the entire exostosis removed to prevent recurrence. The nail bed is repaired to cover the defect.

Interdigital Neuroma (Morton Neuroma)

An interdigital neuroma is a painful affliction involving the plantar aspect of the forefoot. It usually involves the third interspace and is characterized by a well-localized area of pain on the plantar aspect of the foot that radiates into the web space. The symptoms are usually aggravated by ambulation and relieved by rest. As a rule, wearing a tight-fitting shoe aggravates the pain, and walking barefoot often relieves it.

Etiologic Findings

The precise cause of interdigital neuroma has not been determined. It occurs in women about 10 times more frequently than men, and, as a result, high-fashion shoewear has been implicated. Several studies demonstrate that the changes in the nerve appear to occur just distal to the transverse metatarsal ligament. This finding has given rise to the hypothesis that the neuroma results from the constant traction of the nerve against the ligament as the toes are brought into a dorsiflexed position, a theory that would explain the higher incidence in women wearing high-heeled shoes. Although this condition is called interdigital neuroma, it is not a true neuroma. The pathologic changes involve actual degeneration of the nerve fibers associated with deposition of amorphous eosinophilic material that is felt to be consistent with an entrapment neuropathy (Figure 8–31).

Clinical Findings

Symptoms and Signs

Patients with an interspace neuroma usually present with a complaint of localized pain in the metatarsal head region that is increased by walking and relieved by rest and removing the shoe. Palpation of the involved interspace produces sharp pain that often radiates into the toes. There can be a palpable mass, and squeezing the forefoot, thereby narrowing the intermetatarsal space while compressing the mass, often reproduces the patient's symptoms. If this maneuver produces a snapping sensation, it is referred to as a Mulder click. The third interspace is more frequently involved than the second, and it is extremely rare to have involvement of the first or fourth web space. Pain over the metatarsophalangeal joint itself is caused by disease involving the metatarsophalangeal joint, and it is important to distinguish pain in the interspace from pain associated with pathology in the metatarsophalangeal joint. The differential diagnosis of metatarsalgia includes avascular necrosis (Freiberg), synovitis due to mechanical instability, synovial cysts, or even referred pain from tarsal tunnel compression or lumbar disk disease.

Imaging Studies

Radiographs are not helpful in the diagnosis of an interdigital neuroma but may reveal pathology at the metatarsophalangeal joint as the cause of the patient's symptoms. There are several reports regarding the use of ultrasound to evaluate the presence of nerve enlargement, but this is very user dependant. MRI can be used effectively but is rarely necessary.

Treatment

Conservative Management

Conservative management begins with wearing a wider, soft-soled shoe to accommodate the foot without mediolateral compression and lowering the heel. A soft metatarsal support is placed in the shoe proximal to the area of the neuroma, thereby spreading the metatarsal heads and lifting them. Approximately one third of patients will respond to this treatment. Steroid injection into the web space can be helpful in resolving the symptoms but is not without the hazard of local fat atrophy, which can lead to diminished padding under the metatarsal heads or local skin thinning and discoloration.

Surgical Treatment

Surgical excision of the nerve is indicated if conservative treatment fails. A dorsal incision is made in the midline of the involved web space and carried down to the transverse metatarsal ligament, which is cut. The nerve is noted to lie just beneath the transverse metatarsal ligament. A nerve that is quite thickened is reassuring evidence that the correct diagnosis has been made; however, a nerve of normal thickness should still be removed if the clinical diagnosis of neuroma has been made from other evidence. The nerve is delivered into the interspace by plantar pressure and is freed up distally and proximally, transected proximal to the metatarsal head, and then dissected out distally, where it is cut just past its bifurcation. Care is taken not to disrupt the surrounding fatty tissue or intrinsic muscles. A compression dressing is used for 3 weeks after routine wound closure, and ambulation is permitted in a postoperative shoe. Decreased sensation in the toes on either side of the web space is expected postoperatively. Approximately 80% of patients are totally satisfied with the results of the procedure, whereas 20% obtain little or no relief. The precise cause of this failure rate is a bit of an enigma. Obviously in some patients, the diagnosis was incorrectly made and the metatarsophalangeal joint was actually involved.

Recurrent Neuroma

A recurrent neuroma is indeed a true surgical bulb neuroma that has resulted following the transection of the common digital nerve on the plantar aspect of the foot. True neuritic symptoms occur in some cases in which transection was not proximal enough or the nerve became adherent and trapped beneath the metatarsal head. Careful percussion of the plantar aspect to elicit the Tinel sign can frequently localize the cut end of the nerve (bulb neuroma). If the severed nerve can be clinically well localized, reexploration for the neuroma is carried out either through a dorsal or plantar approach. The neuroma is identified and transected to a more proximal level or implanted into muscle, and symptoms are relieved in 60–70% of patients.

Tarsal Tunnel Syndrome

Tarsal tunnel syndrome is a compressive or traction neuropathy of the posterior tibial nerve as it passes behind the medial malleolus. The tarsal tunnel is formed by the fibro-osseous tunnel resulting from the flexor retinaculum as it wraps around the posterior aspect of the medial malleolus (Figure 8–32). Tarsal tunnel syndrome causes poorly localized dysesthesias on the plantar aspect of the foot. The symptom complex is often aggravated by activity and relieved by rest. Some patients complain mainly of nocturnal dysesthesias.

Etiologic Findings

Tarsal tunnel syndrome may arise from a space-occupying lesion within the tarsal tunnel (eg, a ganglion, synovial cyst, or lipoma) or distally against one of the two terminal branches: the medial or lateral plantar nerve. It occasionally follows severe trauma to the lower extremity probably because of edema or scarring. Other causes are severe venous varicosities, tenosynovitis, or a tumor within the nerve. Traction neuropathy can occur in patients who have an excessively valgus hindfoot position, especially those that are unstable. As the patient walks, the posterior tibial nerve is subjected to stretching as it courses around the convex side of the deformity. In more than half of the cases, however, the precise cause cannot be determined.

Clinical Findings

Symptoms and Signs

The diagnosis is entertained after obtaining a history of paresthesias or burning in the posterior tibial nerve distribution. Careful evaluation of the patient in the standing and sitting positions is necessary to check posture and increased fullness, thickening, or swelling in the involved tarsal tunnel area. Careful percussion may elicit a Tinel sign over the posterior tibial nerve in the tarsal tunnel or distally along the divisions of the posterior tibial nerve (the medial calcaneal nerve and medial and lateral plantar nerves).

Muscle weakness is usually not observed, but loss of sensation and two-point discrimination may be occasionally detected.

Electrodiagnostic studies should be carried out to help confirm the diagnosis of tarsal tunnel syndrome. Nerve conduction velocities along the medial plantar nerve to the abductor hallucis muscle (latency <6.2 ms) and of the lateral plantar nerve to the abductor digiti quinti (latency usually <7 ms) should be within 1 ms of each other, otherwise indicating nerve compression in the tarsal tunnel. Motor-evoked potentials that demonstrate a decreased amplitude and increased duration are also felt to be indicative of tarsal tunnel syndrome. The most accurate study for tarsal tunnel syndrome appears to be sensory nerve conduction velocity, although this is also the least reproducible study.

The definitive diagnosis of tarsal tunnel syndrome should be based on (1) the clinical history of ill-defined burning, tingling pain in the plantar aspect of the foot; (2) positive physical findings of Tinel sign along the course of the nerve; and (3) electrodiagnostic studies. If all three factors are not positive, the diagnosis of tarsal tunnel syndrome should be suspect. MRI may be quite useful in demonstrating the presence of a space-occupying lesion.

Treatment

Conservative Management

Tarsal tunnel syndrome should be managed with anti-inflammatory medications and an occasional steroid injection into the tarsal tunnel area. Aspiration and injection of a cyst or ganglion may be attempted but are rarely successful. Immobilization in a polypropylene ankle-foot orthosis may also be useful especially in the patient with unstable valgus who is suffering from a traction injury to the nerve.

Surgical Treatment

Surgical intervention can be considered if conservative management fails. Approximately 75% of patients operated on for tarsal tunnel syndrome are satisfied with the result. The other 25% may continue to have varying degrees of discomfort. The surgical release uses an incision behind the medial malleolus that is carried distally to about the level of the talonavicular joint. The investing retinaculum is exposed and released. The posterior tibial nerve is identified proximal to the tarsal tunnel area and carefully traced distally behind the medial malleolus. The division into its three terminal branches is identified. Because the medial calcaneal branch passes from the posterior aspect of the lateral plantar nerve, the dissection should be carried out along its dorsal aspect. There may be one or more medial calcaneal branches. The medial plantar nerve should be traced distally until it passes through the fibro-osseous tunnel in the abductor hallucis muscle. The lateral plantar nerve should be traced behind the abductor hallucis muscle until it passes toward the lateral aspect of the foot. A preoperative Tinel sign distal to the tarsal tunnel area requires that the area be carefully explored to determine whether there is a ganglion or cyst within the tendon sheath as a cause of the tarsal tunnel syndrome.

Postoperatively, a compression dressing is applied and weight bearing is prohibited for 3 weeks, before progressive ambulation is permitted.

The results following tarsal tunnel release depend on the pathology that is found at the time of surgery. Removal of a space-occupying lesion usually relieves all of the symptoms. Involvement of a single nerve branch, such as the medial or lateral plantar nerve, also portends good results after surgery. If more diffuse pain is felt throughout the foot before surgery and no definite constriction on the nerve is found at exploration, only one half to two thirds of patients can be expected to experience pain relief. Patients with traction neuropathy due to the unstable valgus foot are treated by correction of the instability, usually with arthrodesis, and not with soft-tissue tarsal tunnel release.

Traumatic Neuromas About the Foot

A traumatic neuroma about the foot presents a difficult problem in management because footwear can cause constant irritation of the neuroma. The most frequent cause of traumatic neuroma in the foot is previous surgery. Despite caution in making incisions about the foot, many lesser and occasionally major nerve trunks can be injured. The dorsal aspect of the foot is most frequently involved (Figure 8–33).

Clinical Findings

The clinical evaluation begins with a careful history of the problem and an evaluation of the area involved to determine the precise location of the neuroma, which is essential for proper treatment. Rarely is any type of electrodiagnostic study indicated, and radiographs are not usually necessary.

Treatment

Conservative Management

Attempts to relieve pressure on the neuroma with a large shoe or a carefully designed pad may be of benefit. Occasionally a cortisone injection into the area may help, particularly when a small nerve is involved. Surgical intervention is indicated if conservative measures fail.

Surgical Treatment

Careful planning must be undertaken prior to the excision of a traumatic neuroma. The exact location of the neuroma and the area of sensitivity proximal to it must be determined. The incision must be made as precisely as possible to identify the neuroma and trace the nerve proximally into an area that would not be affected by pressure from shoes and boots. The neuroma is excised, leaving enough nerve to bring the cut end into an area of minimal pressure. The cut end is buried into an excavation in bone, if possible, or beneath a muscle such as the extensor digitorum brevis muscle. When carrying out a resection of the sural nerve, it is important, particularly in an individual who wears heavy work boots, that the end of the nerve is brought proximally enough so that the top of the boot will not press upon the nerve, resulting in continued symptoms.

The results following resection of a traumatic neuroma are quite variable. Initial relief from removing the traumatic neuroma is routine, but unless the nerve is buried where it will not be exposed to pressure, the symptoms may recur in time. It is therefore preferable to bury the end of the nerve into bone, if possible. Resection of most neuromas will accentuate a sensory deficit, but this is usually not a significant clinical problem.

Entrapment of the Sensory Branch of the Deep Peroneal Nerve

Osteophyte formation at the talonavicular or metatarsocuneiform joint may entrap the sensory branch of the deep peroneal nerve as it passes beneath the extensor retinaculum. Patient complaints are of dysesthesias on the foot or difficulty in wearing shoes, depending on the location of the entrapment.

The sensory branch of the deep peroneal nerve passes onto the dorsum of the foot between the extensor hallucis longus and extensor digitorum longus tendons. It continues beneath the extensor retinaculum, coursing along the dorsal surface of the talus and navicular, and more distally across the metatarsocuneiform joints. Osteophyte formation at any point along the course of the nerve may cause sufficient pressure against the nerve to cause an entrapment problem.

Clinical Findings

Symptoms and Signs

The clinical evaluation begins with a careful history regarding the patient's complaint of dysesthesias over the dorsum of the foot. The physical examination demonstrates tingling along the course of the sensory branch of the deep peroneal nerve, which radiates into the first web space. Often the precise location of the nerve entrapment can be identified by careful palpation and by rolling the nerve across the involved bony prominence.

Imaging Studies

Radiographs usually reveal the offending osteophytes, often along the area of the talonavicular or metatarsocuneiform joints. Placing a radiographic marker at the area of maximum tenderness can help to identify the offending bony prominence.

Treatment

Conservative Management

Conservative management consists of attempting to keep the pressure off the involved area, either by padding the tongue of the shoe or by trying to create a pad that will not put pressure directly on the nerve. If these measures fail, decompression of the nerve will usually bring about satisfactory resolution of the condition.

Surgical Treatment

Depending on the area of entrapment (talonavicular or metatarsocuneiform), a slightly curved incision is made and carried down through the retinaculum to expose the nerve. Great caution must be taken during the approach so that the nerve is not inadvertently damaged. The nerve is carefully lifted off of its bed, exposing the osteophytes, which are removed with a rongeur. The bone surfaces are coated with bone wax prior to laying the nerve back on its bed. After wound closure in layers, the foot is immobilized for approximately 3 weeks in a postoperative shoe.

The results following release of the sensory portion of the deep peroneal nerve are usually satisfactory. Because the nerve itself usually is not damaged by the entrapment, a favorable outcome is expected.

The foot is involved in 90% of patients with long-standing rheumatoid arthritis, and the involvement is almost always bilateral. The forefoot is most commonly involved and often contains the first joints to be affected, but deterioration of the subtalar joint has been noted in about 35% of patients and of the ankle joint in about 30%.

Etiologic Findings

The changes in the forefoot are caused by chronic synovitis, which destroys the supporting structures about the metatarsophalangeal joints. The joint capsules are distended and the ligaments destroyed. When these structures no longer function to provide stability for the joint, progressive dorsal subluxation and eventual dislocation of the metatarsophalangeal joints occur. As the metatarsophalangeal joints progress from subluxation to dislocation, the plantar fat pad is drawn distally, and the base of the proximal phalanx eventually comes to rest on the metatarsal head. Thus, the metatarsals are forced into a position of plantar flexion, which results in significant callus formation beneath the metatarsal heads. The changes at the metatarsophalangeal joints result in imbalance of the intrinsic muscles, and severe hammer toe and claw toe deformities usually result.

Significant midfoot and hindfoot pathology is also found in patients with rheumatoid arthritis. A severely flattened longitudinal arch can result from long-standing subtalar joint involvement with subluxation. Pain with less severe deformity is present in isolated talonavicular involvement of the midfoot.

Clinical Findings

Symptoms and Signs

The clinical evaluation of the rheumatoid patient begins with a careful history of the disease and the medications the patient is taking and an attempt to ascertain whether the disease process is currently in an active or a quiescent stage. It is important to obtain some indication of the patient's wound-healing capacity in the foot or elsewhere in the body.

The vascular status of the foot and quality of the skin are noted. The feet are assessed with the patient standing, which will often demonstrate marked deformities of multiple joints or localized involvement of only one or two joints. The patient is then seated, and a careful evaluation of all the joints about the foot and ankle is carried out to determine precisely the degree to which they are affected. Careful palpation of the metatarsophalangeal joints will often demonstrate the degree of the synovial activity as well as the degree of stability of the joints. The plantar aspect of the foot is inspected for the callus formation and past or present ulcerations. Flattening of the longitudinal arch and any hindfoot valgus are evaluated with a careful assessment of joint stability to determine the risk of deformity progression.

Imaging Studies

Radiographs help to assess the number of joints involved and the degree of involvement. Bilateral involvement is frequently asymmetric. Standing radiographs are beneficial in assessing the effect of joint stability on the severity of deformity.

Treatment

Conservative Management

Conservative management includes medical management, carried out by the patient's rheumatologist. The patient with sufficient deformity should wear an extra-depth shoe with a soft accommodative liner to reduce pressure on the metatarsal heads and the toes, which may be severely contracted dorsally. Frequently, the patient is quite comfortable in this shoe and does not require further treatment. With significant hindfoot involvement, an ankle-foot orthosis may be required to help relieve pain by providing adequate stabilization.

Surgical Treatment

The main goal of surgical management of the forefoot is to create a stable foot that will alleviate the pain beneath the metatarsal head region (Figure 8–34). Arthrodesis of the first metatarsophalangeal joint is the procedure most commonly used, with the joint placed in approximately 15 degrees of dorsiflexion in relation to the floor and approximately 15 degrees of valgus position. The lesser metatarsophalangeal joints are corrected by release of the soft-tissue contracture and resection arthroplasty. The metatarsal heads are excised to decompress the metatarsophalangeal joints, and the fat pad is brought back down onto the plantar aspect of the foot by realigning and securing the plantar plates of the joints under the residual metatarsals. The hammer toes can be corrected by closed osteoclasis, which often results in satisfactory realignment. Open hammer toe procedures are also very effective in correcting residual deformities. The toes and metatarsophalangeal joint area are stabilized with longitudinal Kirschner wires postoperatively for approximately 4 weeks.

The results of this rheumatoid forefoot repair are most gratifying in that about 90% of patients will be satisfied with the results. There are few complications, although the blood supply to the toes is always of concern because the procedure is extensive. Occasionally, wound healing is delayed, particularly if the patient is taking high dosages of corticosteroids or antimetabolite drugs.

Hindfoot and ankle disease is usually managed medically unless there is instability and progressive deformity. Orthotic support or bracing can be beneficial, but if the deformity is increasing and the patient's thin skin cannot tolerate further pressure, then surgical stabilization with arthrodesis is necessary. If only a single joint is involved with the rheumatoid process, a less extensive procedure is carried out. For isolated talonavicular rheumatoid arthritis with no significant deformity of the arch, an isolated talonavicular fusion is adequate. If significant deformity is present because of subtalar joint subluxation, a triple arthrodesis is required. Ankle joint involvement is treated with ankle joint fusion or total ankle arthroplasty. The details of the surgical procedures are described elsewhere in this chapter.

Heel pain can be caused by several distinct entities. When evaluating the patient for heel pain, the clinician must attempt to define as precisely as possible the location and, hence, the cause of the pain.

The causes of heel pain are presented in Table 8–3. The causes are quite variable and need to be carefully defined, so that the proper treatment can be chosen.

Clinical Findings

Symptoms and Signs

The clinical evaluation begins with a careful history of the onset and location of the pain. The patient's activities and types of footwear that aggravate and relieve the pain are discussed. Specific inquiry regarding radiation of pain proximally in the lower extremity may suggest lumbar disk disease as the cause. Patients active in sports should be questioned regarding significant changes in their level of activity because heel pain often is the result of increased stress on the foot.

The cause of the patient's heel pain can usually be determined by palpating the area of maximum tenderness.

Plantar fasciitis, the most common cause of plantar heel pain, usually has an area of maximum tenderness along the plantar medial aspect of the heel, which corresponds to the origin of the plantar fascia at the medial calcaneal tuberosity. In most cases, the pain is most severe with the first steps upon arising. The pain is usually aggravated by dorsiflexion of the toes, the so-called windlass stretch, because this applies more tension on the damaged plantar fascia.

Achilles tendonitis/tendinosis typically occurs at one of two discreet sites: at the calcaneal insertion or centered 3.0–4.0 cm proximal to the insertion. Insertional Achilles tendonitis/tendinosis is characterized by pain and swelling that is increased by activity. There is usually tenderness in the posterior midline with local increased warmth. Noninsertional Achilles tendonitis/tendinosis is usually associated with a thickened tendon and often quite severe tenderness to palpation of the thickened area in the midportion of the tendon. Both of these are more degenerative than true inflammatory processes and more properly referred to as tendinosis.

Heel pain can also be caused by inflammation of the retrocalcaneal bursa, which sits between the tendoachilles and the posterior calcaneus and is often associated with the Haglund heel deformity.

Tarsal tunnel syndrome with involvement of the medial calcaneal branches should be investigated by careful percussion of the posterior tibial nerve. Evidence of degenerative disk disease requires careful testing of motor function and sensation more proximally in the calf.

Imaging Studies

Radiographs may demonstrate calcaneal spur formation or calcification at either the insertion of the Achilles tendon or the origin of the plantar fascia. Alternatively, the posterosuperior aspect of the calcaneus may be too prominent and protrude into the Achilles tendon, a condition known as Haglund disease or Haglund deformity, with the symptoms coming from the inflamed retrocalcaneal bursa. A bone scan will sometimes reveal increased activity diffusely about the calcaneus, as may be seen in systemic diseases such as Reiter syndrome, or a discreet area of uptake, as in a stress fracture. MRI scan may help to delineate the degree of the Achilles tendon degeneration present in cases of Achilles tendinosis and can help to identify rupture of the tendon if this is in question.

Treatment

Conservative Management

The conservative management of heel pain depends on the specific cause. Because many causes are related to abnormal stress on the foot, the basic principles involve reducing the stress on the involved area. Activity modification, footwear with a softer, more resilient heel, and use of a soft orthotic device under the longitudinal arch to relieve some of the pressure on the region of pain can be helpful. NSAIDs are often useful, as is physical therapy to teach stretching exercises of the Achilles tendon and plantar fascia. Plantar fasciitis is treated initially with stretching exercises, soft cushioned heel shoes, NSAIDS if they are tolerated, and avoidance of strong toe-off activities such as running and jumping. The use of a night splint to help keep the Achilles tendon and plantar fascia stretched often relieves the acute pain patients experience when they first get up in the morning. Patients who are refractory to treatment may benefit from a steroid injection into the plantar fascia origin, although there is a risk of plantar fascia rupture. Cast immobilization has also been shown to benefit these refractory patients. Recently there is some evidence that injection of platelet-rich plasma may be of benefit to these refractory patients.

In general, the treatment of heel pain is often prolonged, requiring a great deal of patience on the part of the physician and patient. It is important to explain to the patient the nature of the problem and the fact that it is often a chronic condition that requires many months to resolve.

Achilles tendinosis is treated with stretching exercises, activity modification, NSAIDs, and a heel lift. If these modalities are inadequate, then bracing or casting will provide more strain relief to the damaged tissue.

Surgical Treatment

Patients with plantar fasciitis, in whom symptoms cannot be controlled after 9–12 months of conservative management, may become candidates for surgery. The options include orthotripsy or surgical release of the medial half of the plantar fascial origin. With surgical release, the success rate is approximately 75%. Caution must be exercised with the approach to the medial side of the heel to avoid damage to the medial calcaneal branch of the posterior tibial nerve. Disruption of this nerve will cause an area of heel numbness and possibly a troublesome neuroma along the medial side of the heel. An endoscopic approach for plantar fascia release has been described in patients who do not have a plantar heel spur that requires removal. Orthotripsy, while less invasive, still has conflicting literature as to its effectiveness.

Surgical treatment of Achilles tendinosis is offered if 6–9 months of conservative measures do not help to eliminate symptoms. Insertional Achilles tendinosis is treated with debridement of degenerative tendon and excision of bone spurs with repair of the Achilles insertion. If a Haglund deformity is present, it is also resected. Noninsertional Achilles tendinosis is treated with debridement of degenerative tendon. In either case, if the majority of the tendon is nonviable, it must be repaired, often requiring a graft such as the flexor hallucis longus tendon transfer.

General Considerations

Goals of Arthrodesis

Arthrodesis is surgical fixation of a joint to obtain fusion of the joint surfaces. Arthrodesis about the foot and ankle can be effective in achieving the following goals:

1. Elimination of joint pain

2. Correction of deformity

3. Stabilization of the foot or ankle when adequate muscle function or ligamentous support is lacking, as in residual poliomyelitis or the acquired flat foot due to peritalar instability

4. Restoration of function by salvaging a situation in which no reasonable reconstructive procedure is available, as in fusion of the first metatarsophalangeal joint after failed hallux valgus repair

Principles of Arthrodesis

An arthrodesis about the foot and ankle requires adherence to these general principles:

1. To be effective, the arthrodesis must produce a plantigrade foot.

2. Broad, cancellous bony surfaces must be placed into apposition.

3. The arthrodesis site should be stabilized with rigid internal fixation, preferably with interfragmentary compression.

4. When correcting malalignment of the foot, it is imperative that the hindfoot be placed into 5–7 degrees of valgus and the forefoot in neutral position with regard to abduction, adduction, pronation, and supination.

5. The surgical approaches should be carried out in such a way as to minimize the risk of damage to the nerves.

Effects of Arthrodesis on Joint Motion

Following ankle arthrodesis, residual dorsiflexion and plantar flexion movement occurs within the subtalar and transverse tarsal joints, and additional, compensatory motion may develop over time. Arthritic changes in these joints may become symptomatic following ankle arthrodesis, and in time, extension of the fusion may be required.

The subtalar joint and transverse tarsal joints must be viewed as a joint complex similar to the universal joint of a car. Movement in these joints is interrelated. After subtalar arthrodesis, inversion and eversion are lost, but transverse tarsal joint motion in dorsiflexion and plantar flexion remains. Arthrodesis of the talonavicular joint, however, will eliminate most of the subtalar joint motion because rotation must occur around the head of the talus for subtalar motion to occur.

A triple arthrodesis eliminates the subtalar and transverse tarsal joint motion, causing increased stress on the ankle joint and the midtarsal joints distal to the fusion site. A small percentage of patients will develop degenerative changes in the ankle joint following triple arthrodesis. It is imperative, therefore, to carefully evaluate the ankle joint prior to carrying out a triple arthrodesis.

Arthrodesis of the tarsometatarsal joints will not significantly affect motion of the foot and ankle, but a certain degree of stiffness is noted through the midtarsal area following this fusion. Fusion of the first metatarsophalangeal joint places added stress on the interphalangeal joint of the great toe, particularly with poor alignment. Although up to 40% of patients may develop degenerative changes in this joint, they are rarely of clinical significance.

Disadvantages of Arthrodesis

Although arthrodesis is an effective reconstructive tool, the resulting loss of motion places increased stress on the surrounding joints, making them more prone to developing arthritis or worsening preexisting degenerative changes. Thus, correction of a problem without arthrodesis is preferable whenever possible, such as with an osteotomy, tendon transfer, or both.

Ankle Fusion

Indications

The main indications for ankle arthrodesis are the following:

1. Arthrosis of the ankle joint usually secondary to a previous ankle fracture, although primary arthrosis does occur

2. Arthritis secondary to rheumatoid disease

3. Instability with malalignment of the ankle joint as the result of an epiphyseal injury or previous fracture

Technique

The surgical approach preferred by the authors is a transfibular approach (Figure 8–35). The incision begins along the fibula, approximately 10 cm proximal to the tip of the fibula, and is carried distally along the shaft of the fibula and then curves toward the base of the fourth metatarsal. In this way, the incision avoids the sural nerve posteriorly and the superficial peroneal nerve dorsally. The flaps that are created are full thickness, to lessen the possibility of wound healing problems. The dissection is carried across the anterior aspect of the ankle joint, to the medial malleolus and along the lateral aspect of the neck of the talus. Posteriorly, the fibula and the posterior aspect of the ankle joint are exposed, while distally, the subtalar joint and sinus tarsi area are exposed. The fibula is removed approximately 2 cm proximal to the joint, after which the residual cartilage and subchondral bone are removed from the distal tibia (Figure 8–36). This cut should be made as perpendicular as possible to the long axis of the tibia and should extend to the medial malleolus but not through it. The foot is placed into a plantigrade position and a cut made in the dome of the talus parallel to the cut in the tibia, thereby creating two flat surfaces and correcting any malalignment. At this point, the ankle should be aligned in neutral position, insofar as dorsiflexion and plantar flexion are concerned, and at about 5 degrees of valgus. The degree of rotation should be equal to that of the opposite extremity, which is usually 5–10 degrees of external rotation. If the two joint surfaces do not easily oppose each other, it is because the medial malleolus is too long, and the malleolus should be exposed through a dorsomedial incision and the distal centimeter removed.

The two flat surfaces should now be in total apposition, with little or no pressure being exerted. Temporary fixation is obtained by inserting two 0.062-inch K-wires. Interfragmentary compression is gained with at least two 6.5-mm cancellous screws. These screws should be placed to gain adequate interfragmentary compression (Figure 8–37). Following insertion of the screws, there should be rigid fixation of the arthrodesis site. Because the joint surfaces are fully opposed, there is no room for bone grafting. In the immediate postoperative period, a firm compression dressing incorporating plaster splints is applied. After swelling is decreased, a short leg cast is applied and weight bearing is not allowed for 6 weeks. Weight bearing is then allowed with the short leg cast in place for another 6 weeks. Arthrodesis generally occurs following 12 weeks of immobilization.

Complications

Nonunion of the ankle joint, although uncommon, does occur. Using the surgical technique described earlier, a fusion rate of 90% can be anticipated. If nonunion occurs, bone grafting and further internal fixation may be required.

Malalignment of the ankle joint with the foot in too much internal rotation is poorly tolerated and often requires revision surgery. Excessive plantar flexion causes a back knee thrust and eventually some knee discomfort; excessive dorsiflexion causes increased stress on the heel (that can usually be treated with adequate padding); varus deformity may cause subtalar joint instability; excessive valgus causes stress on the medial aspect of the knee joint.

It is extremely important not to place any pin or screw across the subtalar joint for fear of damaging the posterior facet, which may lead to arthrosis.

Special Considerations

Avascular necrosis of the talus requires excision and tibiocalcaneal fusion or a fusion that bypasses the necrotic bone. Bone grafting may also be necessary when attempting to carry out a fusion after a severely comminuted pilon fracture because there are often defects that affect stability due to the previous crushing of cancellous bone.

Total Ankle Arthroplasty

Total ankle arthroplasty is an alternative to ankle arthrodesis for painful arthrosis of the ankle joint. Advantages include maintenance of some ankle joint motion with a more normal gait and thus less stress on adjacent joints. Unfortunately the disadvantages of the procedure are that it is technically difficult with a steep learning curve, there is a higher complication rate than with arthrodesis, and the long-term survival rate is unknown. The intermediate-term survival rate of the Agility total ankle reported by Saltzman suggests that the outcome is durable in selected patients. The procedure is performed through an anterior incision in all of the implants that are currently available in the United States (ie, the Agility, the Salto-Talaris, and the INBONE), all of which are two-part implants (Figure 8–38). There are several other prostheses, including the STAR, the Mobility, and the Hintegra, used primarily in Europe that have reported promising early results; these are three-part implants with a polyethylene mobile bearing. There is the expectation that these newer designs will eventually be approved by the U.S. Food and Drug Administration (FDA) and become available in the United States. Studies to date have shown no advantage to the mobile bearing implants, although there is the possibility of less polyethylene wear; the disadvantage is the potential for instability of the mobile bearing. There is general consensus that the ideal patient is older, thin, and less active, but there are no clinical data that specifically support this. Proponents of arthroplasty have suggested that their patients may be able to have a more active lifestyle than those with arthrodesis, but there are no studies that actually look at this question. There are studies that show that patients after arthroplasty have a greater ability to perform light recreational activities such as swimming, biking, and hiking than they did before surgery. Survey data suggest that physicians recommend that arthrodesis patients participate in low-impact sports.

Subtalar Arthrodesis

Indications

The main indications for subtalar arthrodesis are the following:

1. Arthrosis of the subtalar joint, usually following a calcaneal fracture, but occasionally for primary arthrosis of the joint

2. Varus or valgus deformity secondary to rheumatoid arthritis

3. Varus deformity secondary to residual clubfoot or possibly following compartment syndrome

4. Unstable subtalar joint secondary to poliomyelitis, a neuromuscular disorder, or tendon dysfunction such as posterior tibial tendon dysfunction

5. Symptomatic talocalcaneal coalition without secondary changes in the talonavicular or calcaneocuboid joints

Technique

The incision for subtalar arthrodesis begins at the tip of the fibula and is carried distally toward the base of the fourth metatarsal. As the incision is deepened, the sural nerve or one of its branches should be carefully noted and retracted. Small “twigs” of nerve may be present that unfortunately may be cut and give rise to a painful neuroma. The sinus tarsi area is exposed by reflecting the extensor digitorum brevis muscle distally. The use of a lamina spreader in the subtalar joint will enhance the exposure.

The articular cartilage is removed from the joint surfaces, which include the middle and posterior facets. The bony joint surfaces are then deeply feathered or scaled using a small osteotome. These cuts through the subchondral bone will greatly enhance the possibility of fusion. The area around the floor of the sinus tarsi and anterior process region can be carefully shaved to obtain local bone graft for the fusion.

The alignment of the subtalar joint is critical. It must be aligned into approximately 5–7 degrees of valgus position, producing a supple transverse tarsal joint. If it is placed in varus position, the foot is stiff and the patient will walk on the side of the foot.

Rigid fixation of the subtalar joint is achieved by using a 7-mm cannulated interfragmentary screw starting at the posterior tip of the calcaneus and passing into the body or neck of the talus. The guide pin is first placed up into the posterior facet, the subtalar joint is then manipulated into proper alignment, and the guide pin is passed into the talus. The alignment of the screw is verified on radiograph, and the screw inserted.

Following adequate internal fixation, the local bone graft is packed into the sinus tarsi area. Additional bone may be obtained from the area of the medial malleolus, the proximal tibia, or occasionally the iliac crest, although the latter site significantly adds to the morbidity of the procedure.

Postoperatively, a firm compression dressing incorporating plaster splints is applied. A short leg cast is applied, and weight bearing is not allowed for 6 weeks. The cast is changed, and weight bearing is not allowed for another 6 weeks. Twelve weeks of immobilization generally achieves an arthrodesis.

Complications

Nonunion of the subtalar joint is uncommon, although it can occur. Careful surgical technique and heavy scaling of the joint surfaces can help to prevent this complication. If nonunion occurs, bone grafting and added fixation are required to attempt to achieve a solid union.

Misalignment of the subtalar joint may also be a complication. An excessive valgus deformity following subtalar fusion may result in impingement laterally against the fibula or peroneal tendons. It will also cause excessive stress along the medial aspect of the midfoot and occasionally the knee joint. A varus deformity of the subtalar joint imparts rigidity to the transverse tarsal joint, resulting in stiffness of the forefoot. This also increases pressure along the lateral aspect of the foot, particularly in the area of the base of the fifth metatarsal.

Special Considerations

The patient with rheumatoid arthritis or posttraumatic complications may have lateral subluxation of the calcaneus in relation to the talus, which usually requires computed tomography (CT) scanning for identification. The calcaneus must be displaced medially at operation to align it with the lateral aspect of the talus and place it under the tibia in a proper weight-bearing position. If the calcaneus is fused with significant lateral deviation, the abnormal alignment places added stress on the ankle and midfoot region.

Special attention to the peroneal tendons is necessary when a subtalar arthrodesis is done to correct an old calcaneal fracture. Protrusion of the lateral wall of the body of the calcaneus from the healed fracture results in impingement on the peroneal tendons beneath the fibula. This protrusion must be carefully excised when the subtalar fusion is carried out, so that the lateral aspect of the talus and calcaneus are in line. Further, the peroneal tendon sheath should be dissected subperiosteally off the calcaneus to provide tendon sheath to protect the peroneal tendons from the raw, bony surface of the calcaneus.

Occasionally a bone block distraction arthrodesis of the subtalar joint is performed in cases of severe deformity after a calcaneus fracture. If the talus has assumed a horizontal position because of flattening of Böhler's angle, this can cause limited ankle joint dorsiflexion. Placing a tricortical block of iliac crest into the posterior facet of the subtalar joint will help to improve the overall alignment of the hind foot and regain ankle joint dorsiflexion.

Talonavicular Arthrodesis

Indications

Talonavicular arthrodesis is indicated in the following conditions:

1. Posttraumatic injury, rheumatoid arthritis, or primary arthrosis

2. Unstable talonavicular joint secondary to rupture of the posterior tibial tendon and the peritalar ligaments, and rheumatoid arthritis

3. In conjunction with double or triple arthrodesis of the hindfoot

Technique

The talonavicular joint is approached through a medial or dorsomedial incision that starts in the region of the naviculocuneiform joint and extends to the neck of the talus. The soft tissues are stripped from around the joint and the articular cartilage removed with a curet or curved osteotome. Distraction of the joint by placing a towel clip into the navicular often facilitates exposure and debridement of the joint. Correct alignment of the talonavicular joint is extremely critical because this fusion essentially eliminates motion in the subtalar joint. The fusion position of the subtalar joint is 3–5 degrees of valgus with the forefoot in a plantigrade position (Figure 8–39). After the foot has been properly aligned to correspond to the opposite foot, fixation of the joint is carried out. Proper alignment of this joint is particularly critical when treating the laterally subluxed talonavicular joint in the patient with a ruptured posterior tibial tendon. The internal fixation is carried out by using interfragmentary compression with a single large screw (6.5 mm) or two smaller screws (4.0 mm) or by using multiple staples.

Postoperatively, the patient is immobilized in a non–weight-bearing cast for 6 weeks followed by a weight-bearing cast for an additional 6 weeks.

The talonavicular joint has a relatively high incidence of nonunion, which is probably the result of the difficulty in exposing the joint. If the joint is also approached medially to gain additional exposure, the surfaces can be well scaled, and the fusion rate should approach 90%.

Complications

Complications of nonunion and misalignment are similar to those discussed for subtalar joint fusion.

Special Considerations

An isolated talonavicular joint fusion will usually produce a satisfactory result, particularly in relatively sedentary patients older than 50 years. In younger, more active individuals with no other affliction (eg, rheumatoid arthritis), consideration should be given to including the calcaneocuboid joint at the same time to obtain a more stable transverse tarsal joint and enhance the fusion of the talonavicular joint through added stability.

Double Arthrodesis (Calcaneocuboid and Talonavicular Joints)

Indications

In recent years, double arthrodesis has evolved as a procedure that provides the same degree of stability to the foot as a triple arthrodesis (Figure 8–40). By locking the transverse tarsal joint (calcaneocuboid and talonavicular), further subtalar motion is prevented because these three joints function together. This procedure is also indicated in the younger, active patient in whom an isolated talonavicular fusion is contemplated because it gives added stability to the foot.

Indications for double arthrodesis are as follows:

1. Arthrosis of the talonavicular and calcaneocuboid joints (eg, following trauma)

2. Unstable talonavicular and calcaneocuboid joint following rupture of the posterior tibial tendon or neuromuscular disease when a flexible subtalar joint is present

3. Arthrosis of the talonavicular joint or calcaneocuboid joint in an active individual, usually younger than 50 years of age, to give the midfoot a greater degree of stability

Technique

The talonavicular joint is approached through a medial or dorsomedial incision, as previously described, and the calcaneocuboid joint is approached through the same incision along the lateral side of the foot as was described for subtalar fusion. Once these joints are exposed, the joint surfaces are denuded of articular cartilage and the subchondral bone is heavily feathered.

The alignment when carrying out a double arthrodesis is extremely critical because once this fusion has been achieved, the subtalar joint or the transverse tarsal joints no longer move. Therefore, the foot must be placed into a plantigrade position prior to the fixation of the arthrodesis site. The desired position is 5 degrees of valgus of the calcaneus, neutral abduction and adduction of the transverse tarsal joint, and correction of any forefoot varus that is present. This alignment creates a plantigrade foot. The fixation of the talonavicular joint is done first with the insertion of a screw (6.5 mm) or screws (4 mm) or possibly the use of multiple staples. The calcaneocuboid joint is then fixed the same way. Postoperative care is the same as for other foot fusions.

Complications

Complications of nonunion and malalignment are similar to those discussed for subtalar joint fusion.

Triple Arthrodesis

The triple arthrodesis is a fusion of the talonavicular, calcaneocuboid, and subtalar joints (Figure 8–41). In the past, it was the procedure of choice for all hindfoot problems, before isolated fusions became more accepted. Now, this procedure is still commonly used when limited fusions are inadequate.

Indications

Indications for triple arthrodesis are as follows:

1. Arthrosis secondary to trauma involving the subtalar, talonavicular, or calcaneocuboid joints

2. Arthrosis or instability of the talonavicular or calcaneocuboid joints in association with a fixed deformity of the subtalar joint

3. Instability of the foot secondary to posterior tibial tendon dysfunction with a fixed subtalar joint that cannot be realigned by a double arthrodesis

4. Unstable hindfoot secondary to poliomyelitis, nerve injury, or rheumatoid arthritis

5. Symptomatic, unresectable calcaneonavicular bar

6. Malalignment of the hindfoot secondary to trauma such as a crush injury or compartment syndrome

Technique

The triple arthrodesis is carried out as previously described for subtalar fusion and talonavicular fusion. The foot is fixed after manipulation back into a plantigrade position (3–5 degrees of valgus of the subtalar joint), neutral position as far as abduction and adduction of the transverse tarsal joint, and correction of forefoot varus. Postoperative care is the same as for subtalar fusion.

Complications

The main complication is failure of fusion of one of the joints, but this is uncommon, as the successful fusion rate exceeds 90%. The talonavicular joint is most likely to have nonunion. Malalignment of the foot or forefoot may require revision and technically is a difficult procedure. The sural nerve may become entrapped or disrupted through the lateral approach.

Tarsometatarsal Arthrodesis

Arthrodesis in the tarsometatarsal area may involve a single tarsometatarsal joint, usually the first joint, or multiple joints. The fusion mass not infrequently will extend proximally to include the intertarsal bones and sometimes even the naviculocuneiform joints. A careful determination of the involved joints is important when considering a tarsometatarsal fusion for a patient with posttraumatic disorders. At times, in addition to the plain radiograph, a CT scan and bone scan may be necessary to help in precisely defining the involved area.

Indications

The indications for a tarsometatarsal fusion are as follows:

1. Hypermobility of the first metatarsocuneiform joint associated with a hallux valgus deformity in a small percentage of patients with a bunion deformity

2. Arthrosis involving one or more of the tarsometatarsal joints either resulting from trauma or as a primary disease process

3. Arthrosis associated with a deformity resulting from an old Lisfranc fracture-dislocation

Technique

The surgical approach to the first metatarsocuneiform joint is through a dorsomedial longitudinal incision to expose the joint. If multiple joints are involved, the second incision is centered over the second metatarsal, through which the lateral side of the first and all of the second and third metatarsocuneiform joints can be adequately viewed (Figure 8–42). The incision must be sufficiently long to permit adequate exposure of the joints and must be extended proximally if the naviculocuneiform joints are going to be fused as well. Cautious dissection is necessary, as there are numerous superficial nerves as well as the neurovascular bundle (dorsalis pedis and superficial branch of the deep peroneal nerve) passing over the area of the second metatarsocuneiform joint in this approach. If the fourth and fifth metatarsocuboid joints are to be fused, then a third longitudinal incision is made over this area to enable adequate exposure. The articular cartilage is carefully removed from the tarsometatarsal and intertarsal joints, depending on the extent of the fusion mass. The bones are heavily feathered to create a good environment for healing. If a deformity is present (usually an abduction deformity of the foot or possibly dorsiflexion), it should be corrected. The first metatarsocuneiform joint is aligned and fixed using 4-mm cancellous screws or a dorsomedial plate. Interfragmentary longitudinal compression of the other joints is obtained to prevent possible nonunion. The screw pattern found to be most useful for the first metatarsocuneiform joint is one brought from the dorsal aspect of the cuneiform directed distally, and a second screw from the dorsal aspect of the metatarsal base directed proximally, crossing the metatarsocuneiform joint. Care must be taken to also correct any dorsiflexion or abduction deformity that is present.

Postoperatively, the joint is placed in a short leg, non–weight-bearing cast for 6 weeks and then in a weight-bearing cast for another 6 weeks.

Complications

The possibility of nonunion exists, but with interfragmentary compression, this risk is minimized. If nonunion occurs, bone grafting may be required as well as improved internal fixation. When multiple tarsometatarsal joints are fused, there is a moderate amount of swelling and tension placed against the incisions. It is critical postoperatively to use a compression dressing to minimize the risk of swelling and prevent possible wound sloughing. If sloughing occurs, it must be treated appropriately, and occasionally, skin grafting is required.

A tarsometatarsal fusion involving multiple joints may cause a plantar callus because one of the metatarsals has been placed in a position of too much plantar flexion. Osteotomy at the base of the metatarsal may be necessary to realign the metatarsal.

Staples should be avoided as a means of internal fixation of the tarsometatarsal joints because they have a tendency to cause dorsiflexion of the metatarsals, which could result in transfer pressure problems under the uninvolved metatarsal heads.

First Metatarsophalangeal Joint Arthrodesis

See the discussion of hallux valgus at the beginning of the chapter.

Interphalangeal Joint Arthrodesis (Hallux Arthrodesis)

Indications

Interphalangeal joint arthrodesis is usually indicated for the following problems:

1. Arthrosis, usually secondary to trauma or occasionally following a first metatarsophalangeal joint arthrodesis

2. Stabilization of the interphalangeal joint when carrying out a transfer of the extensor hallucis longus into the neck of the first metatarsal (first toe Jones procedure)

Technique

The interphalangeal joint is approached through a dorsal transverse incision centered over the joint. Usually, an ellipse of skin is removed, exposing the ends of the involved joints. Using a small power saw, the end of the distal portion of the proximal phalanx and the proximal portion of the distal phalanx are removed, placing the distal phalanx into approximately 5–7 degrees of plantar flexion and 3–4 degrees of valgus position. Internal fixation is achieved by using a longitudinal screw (4 mm) or crossed K-wires, or both.

A postoperative shoe is used, with weight bearing allowed but avoiding the toe-off phase of gait until fusion occurs, usually in 8 weeks.

Complications

Nonunion of interphalangeal joint fusion is uncommon. If it does occur, it often is asymptomatic and does not require treatment. If it is symptomatic, usually the fusion will need to be revised because the area is too small for adequate bone grafting.

Congenital flatfoot is the term used to describe a flatfoot present since birth. The condition may not be apparent during the early years of life but is usually identified toward the end of the first or during the second decade. The typical asymptomatic flexible flatfoot is probably a normal variant of the longitudinal arch. This deformity must be differentiated from the symptomatic flexible or more rigid flatfoot, which usually will become symptomatic in the early teen years and is often caused by a tarsal coalition. A tarsal coalition is the union of two or more tarsal bones, usually occurring between the calcaneus and the navicular or between the talus and the calcaneus. This process is a congenital failure of segmentation between the bones of the hindfoot. Coalitions are usually not symptomatic until adolescence, with symptoms brought on by increasing stiffness of the hindfoot as the cartilaginous coalition begins to ossify. These individuals have a fairly flexible foot until adolescence, when the foot often becomes somewhat more rigid and symptomatic.

The patient with a tarsal coalition will frequently present with a peroneal spastic flatfoot, usually around the age of 10–12 years. The theory is that the foot is locked in a valgus position by the peroneal muscle spasm that is trying to immobilize the painful peritalar joints. The navicular bone usually forms from three ossification centers inside the original cartilage, and occasionally, the medial center fails to coalesce with the main body, leaving a synchondrosis that is called an accessory navicular. Flatfoot associated with an accessory navicular bone usually becomes symptomatic in the early to mid teenage years and may be unilateral or bilateral.

Residual congenital deformity from conditions such as clubfoot or congenital vertical talus is present from birth and is discussed in Chapter 10, “Pediatric Orthopedic Surgery.”

The patient with generalized dysplasia such as Marfan syndrome or Ehlers-Danlos syndrome may present with flatfoot. A generalized ligamentous laxity will be present from the time of birth, and the diagnosis is usually already known.

Clinical Findings

Symptoms and Signs

The clinical evaluation begins with the patient in a standing position. In all cases of congenital flatfoot, the longitudinal arch flattens when the patient is standing. In the case of tarsal coalition with peroneal spastic flatfoot, the calcaneus is in a severe fixed valgus position. A tarsal coalition or an accessory navicular may be unilateral, as well as the residuals of a congenital deformity such as clubfoot or congenital vertical talus. The symptomatic and asymptomatic flexible flatfoot and the generalized dysplasias are present bilaterally.

The physical examination of these patients is extremely important. The asymptomatic flexible flatfoot will usually demonstrate a satisfactory range of motion and no contracture of the Achilles tendon. The symptomatic flexible flatfoot, however, will almost invariably demonstrate an equinus contracture. To adequately test for tightness of the Achilles tendon, the head of the talus is covered with the navicular, after which the foot is brought up into dorsiflexion with the knee extended. If the foot is brought into dorsiflexion, permitting lateral subluxation of the talonavicular joint, the examiner often is fooled into thinking that dorsiflexion is adequate when indeed it is not.

The patient with tarsal coalition usually demonstrates restricted hindfoot motion secondary to peroneal spasm and to the cartilaginous or bony bar. The peroneal tendons can actually be felt to be bow-strung behind the fibula, not permitting any passive or active inversion of the subtalar joint to occur. On occasion, clonus can be elicited. As a rule, stressing of these joints causes the patient increased discomfort. In flatfoot associated with an accessory navicular, pain is present over the prominence. Frequently, stressing of the posterior tibial tendon aggravates the condition. The patient with residual congenital deformity often demonstrates a certain degree of stiffness of the foot and, not infrequently, varying degrees of deformity of the remainder of the foot. The patient with generalized dysplasia demonstrates marked hypermobility of all the joints, with no contractures whatsoever.

Imaging Studies

The radiographic evaluation is useful in differentiating the various types of flatfoot. In almost all cases, the lateral view shows a lack of normal dorsiflexion pitch of the calcaneus, which is approximately 20 degrees or more. In symptomatic flexible flatfoot, the calcaneus may even be in a mild degree of equinus position. On the lateral radiograph, a line drawn through the long axis of the talus and first metatarsal will demonstrate an angle of more than 30 degrees in severe flatfoot, 15–30 degrees in moderate flatfoot, and 0–15 degrees in mild flatfoot (Figure 8–43).

The calcaneonavicular coalition is best observed on an oblique radiograph and is identified as a bridge from the anterior process of the calcaneus to the inferior lateral aspect of the navicular. The subtalar or talocalcaneal bar is best demonstrated on a CT scan taken in the coronal plane. Flatfoot associated with an accessory navicular demonstrates the accessory bone along the medial side of the navicular, but occasionally a medial oblique view is necessary to outline the size of the fragment. In a patient with a residual congenital deformity, such as a clubfoot or congenital vertical talus, the changes about the foot will often be sufficient to make the diagnosis fairly obvious. The patient with generalized dysplasia often demonstrates complete collapse of the longitudinal arch.

Treatment

Conservative Management

Conservative management is undertaken for congenital flatfoot deformities. A longitudinal arch support may benefit the patient but is usually not necessary for the asymptomatic flexible flatfoot. For symptomatic flexible flatfoot, a semirigid longitudinal arch support and Achilles stretching exercises may be of some benefit.

The tarsal coalition can be treated conservatively with a short leg walking cast, followed by a polypropylene ankle-foot orthosis or a University of California Biomechanics Laboratory (UCBL) insert. If adequate pain relief is achieved, further treatment is not necessary. Flatfoot with an accessory navicular may respond to modification of the shoe to relieve some of the pressure from the involved area. Occasionally, the use of a longitudinal arch support will relieve the pressure.

Residual flatfoot resulting from congenital problems can be treated with an ankle-foot orthosis or UCBL insert if symptomatic. The patient with generalized dysplasia usually does not require any treatment at all.

Surgical Management

Surgical procedures are never appropriate for asymptomatic flatfoot. Symptomatic flexible or semiflexible flatfoot occasionally is treated surgically, particularly if equinus contracture is observed after age 5 or 6 years. A significant equinus contracture may benefit from lengthening of the Achilles tendon. A lateral column lengthening procedure, such as an Evans calcaneal osteotomy, is indicated in cases of symptomatic flexible flatfoot that have failed conservative management. This procedure helps to correct heel valgus and forefoot abduction and should be done as late into growth as possible to avoid disturbing open growth centers. Rarely should a triple arthrodesis be carried out because this leaves a young patient with a very stiff foot.

A tarsal coalition that does not respond to conservative management may require resection. The surgical approach to the calcaneonavicular bar is identical to that of the subtalar joint. The bar is carefully outlined and then resected in its entirety. Talocalcaneal coalitions are resectable throughout the adolescent years, if less than 20% of the posterior facet of the subtalar joint is involved or if the coalition is confined only to the middle facet. More extensive involvement of the subtalar joint in an adolescent or any bar in an adult patient is an indication for subtalar arthrodesis. The approach is through a medial incision centered over the middle facet, and caution is taken to carefully reflect the tendons and posterior tibial nerve. The extent of the coalition is identified, and it is resected to expose the area of normal-appearing articular cartilage. Bone wax is applied to the edges or a free fat graft is inserted to prevent re-formation of the bar. Flatfoot associated with an accessory navicular may require excision of the accessory navicular and plication of the posterior tibial tendon (Kidner procedure). This fairly successful operation is usually carried out during the late adolescent years.

Residual congenital deformity or generalized dysplasias usually will not require surgical management. In severe cases, a triple arthrodesis is indicated after the foot has matured.

Acquired Flatfoot Deformity

Acquired flatfoot deformity is a condition affecting a foot that at one time had a normal functioning longitudinal arch. Over time, the arch progressively flattens, often causing the foot to become symptomatic. This deformity is different from congenital flatfoot deformity, present since birth. Acquired flatfoot deformity in the adult may be caused by the following conditions:

1. Posterior tibial tendon dysfunction

2. Arthrosis of the tarsometatarsal joints, which may be primary or secondary to a previous Lisfranc fracture or dislocation

3. Charcot changes in the midfoot resulting from a peripheral neuropathy

4. Talonavicular collapse resulting from trauma or rheumatoid arthritis

Acquired flatfoot deformities are complex deformities that affect different areas of the midfoot and hindfoot. The deformities may include dorsal subluxation of the talonavicular joint and tarsometatarsal joints, abduction of the forefoot, valgus deformity of the hindfoot, or all three. The extent of the deformity varies widely and is usually progressive. Depending on the etiology, acquired flatfoot deformity may affect a patient bilaterally.

Clinical Findings

Symptoms and Signs

A careful history is important to help distinguish among differing causes of acquired flatfoot deformity. Usually, no specific traumatic event is recalled by the patient who presents with dysfunction of the posterior tibial tendon. In approximately half of patients with tarsometatarsal joint arthrosis, a Lisfranc fracture-dislocation has occurred, whereas the other half has primary arthrosis. The patient with Charcot foot usually gives a relevant history of the cause of the peripheral neuropathy, such as diabetes. The patient with collapse of the talonavicular joint gives a history of prior trauma to the talus or navicular or has rheumatoid arthritis, which causes disruption of the spring ligament complex.

The physical examination begins by observing the foot with the patient standing, observing for unilateral or bilateral flattening of the longitudinal arch. Varying degrees of abduction of the forefoot and hindfoot valgus should also be evaluated.

The patient with posterior tibial tendon dysfunction demonstrates little or no active inversion strength. Usually, the posterior tibial tendon is thick and swollen, and there is increased warmth and pain to palpation over the tendon sheath. When the patient is asked to stand on tiptoe, the involved calcaneus remains in valgus position rather than inverting, as normally occurs. When the patient is viewed from the posterior aspect, more toes are visible laterally on the involved foot than the uninvolved foot, commonly known as the “too many toes sign.”

Arthrosis of the tarsometatarsal joints creates a deformity of abduction of the forefoot with varying degrees of dorsiflexion, giving rise to a rather prominent medial cuneiform. Not infrequently, palpable osteophytes are present on the dorsal and plantar aspect of the tarsometatarsal joints.

A Charcot foot presents with varying degrees of swelling and deformity. In the early stages, the foot demonstrates generalized swelling and increased warmth, with loss of sensation in a stocking-glove distribution. Deformity may vary from a mild flat foot to a severe rocker-bottom deformity. It is important to palpate for bony prominences on the medial and plantar aspects of the foot that make it at risk for ulcerations.

In the patient with rheumatoid arthritis, most of the changes occur within the talonavicular joint. In this case, the head of the talus is often palpable on the plantar medial aspect of the foot. When the subtalar joint is more involved, a fixed hindfoot valgus deformity is usually present as well.

The posttraumatic deformity may vary, depending on precisely which joints are involved. If trauma led to a collapse of the navicular, the longitudinal arch is flattened with little forefoot abduction, and the head of the talus is often palpable on the plantar medial aspect of the foot. There is usually little or no motion in the hindfoot and midfoot joints.

Imaging Studies

Radiographs usually differentiate the cause of the problem. In the patient with posterior tibial tendon dysfunction, there is sagging of the talonavicular joint and abduction of the navicular on the head of the talus. The patient with tarsometatarsal joint arthrosis demonstrates typical degenerative changes at the affected joints, along with varying degrees of lateral and dorsal subluxation of the joints. Patients with Charcot foot demonstrate characteristic changes seen in a neuropathic joint, including dramatic bone destruction and joint dislocations (Figure 8–44). The patient with rheumatoid arthritis demonstrates the typical destructive changes observed with this disease process, with joint space narrowing but little osteophyte formation.

Treatment

Conservative Management

Conservative management is aimed at providing support to the longitudinal arch and ankle with a polypropylene ankle-foot orthosis (AFO). The orthosis must be shaped to accommodate any prominences that might be present. Unfortunately, these prominences present the potential for skin breakdown, particularly in the neuropathic foot. A rocker-bottom-type shoe with an adequate toe box is sometimes indicated to give the patient a smoother gait pattern.

Surgical Treatment

The surgical management of these various conditions is specific for each problem. Posterior tibial tendon dysfunction with a satisfactory ROM of the joints of the hindfoot and midfoot can be treated with reconstruction of the posterior tibial tendon, using a flexor digitorum longus tendon transfer. A calcaneal osteotomy is performed as well, if a significant valgus deformity of the heel is present. Alternatively, a lateral column lengthening, consisting of a calcaneal-cuboid distraction arthrodesis, can be used to correct a flexible flatfoot with significant abduction of the forefoot. When a fixed deformity is present in the hindfoot or forefoot, a triple arthrodesis is indicated.

The patient with Charcot foot is treated in a short leg cast until the acute process subsides, after which a polypropylene AFO is used. Occasionally, a bony prominence that continues to cause skin breakdown may be excised to permit the patient to use an AFO. In extreme rocker-bottom deformities, midfoot correction with an osteotomy may be required. The rheumatoid patient usually requires stabilization of the involved area with an isolated talonavicular fusion if little deformity is present, or a triple arthrodesis if there is a hindfoot or midfoot deformity.

The posttraumatic foot with involvement of the talonavicular joint requires a triple arthrodesis. The fusion may need to be extended distally to include the naviculocuneiform joints if arthrosis is present at these joints.

The patient with arthrosis of the tarsometatarsal joints responds well to surgical management by realigning the foot and carrying out arthrodesis of the involved joints.

Cavus foot deformity is characterized by an abnormal elevation of the longitudinal arch, with resulting decrease in the plantar weight-bearing area and stress concentrated on the metatarsal heads. The condition may be aggravated by clawing of the toes, further reducing the forefoot weight-bearing area. Generalized stiffness of the joints is common, causing the patient to avoid prolonged use of the foot.

Etiologic Findings

The various causes of cavus foot deformity include the following:

1. Anterior horn cell disease, such as poliomyelitis, diastematomyelia, and spinal cord tumor

2. Nerve disorders, such as Charcot-Marie-Tooth disease and spinal dysraphism

3. Muscular diseases, such as muscular dystrophy

4. Long tract and central diseases, such as Friedreich ataxia and cerebral palsy

5. Idiopathic conditions, such as residual clubfoot, arthrogryposis, and cavus foot of undetermined cause

6. Posttraumatic disorders following injuries, such as compartment syndrome or crush injury

Anatomy

Cavus foot deformity is extremely variable in its presentation, from a mild to extremely severe degree of cavus. The types of deformities can be classified based on localizing of the area of deformity.

Posterior Cavus Deformity

This deformity mainly involves the calcaneus, which has a dorsiflexion pitch angle of greater than 40 degrees measured on a weight-bearing lateral radiograph. Normally, the dorsiflexion pitch to the calcaneus is approximately 20 degrees. Some degree of varus deformity of the heel is usually present as well.

Anterior Cavus Deformity

In anterior cavus deformity, there is a forefoot equinus deformity with the hindfoot in a neutral position. The anterior cavus may be localized, mainly involving the first and second metatarsal, or it may be more global, with the entire forefoot in a position of plantar flexion. Some degree of adduction of the forefoot is usually present.

Combined Cavus Deformity

In a combined cavus deformity, which is the most severe, there are both anterior and posterior components.

Clinical Findings

Symptoms and Signs

A careful history regarding the onset of the condition and progression is important. A detailed family history should also be obtained because idiopathic cavus deformity does tend to run in families. Progression of deformity should be ascertained, particularly in the adolescent, because it may indicate a spinal cord abnormality or neoplasm. Activity level and ambulation should also be carefully evaluated as markers of progression of neural or muscular disease.

The degree of deformity of the foot must be examined with the patient in a standing position. This also reveals any evidence of atrophy of the calf muscles, as seen in Charcot-Marie-Tooth disease, clubfoot, or arthrogryposis. The active and passive ROM of the joints of the foot and ankle should be carefully measured. The muscle strength of each muscle must be carefully evaluated, especially if considering a tendon transfer. The degree of deformity and flexibility of the rearfoot, forefoot, metatarsophalangeal joints, and lesser toes must be ascertained. The presence of a tight plantar fascia should also be noted. The lateral ankle ligaments must be evaluated for integrity because they often become stretched out with long-standing varus heel deformity.

Imaging Studies

Weight-bearing radiographs of the foot and ankle are obtained to help classify the type of cavus deformity and formulate a treatment plan. Any degree of arthrosis or varus tilting of the talus in the ankle mortise is also evaluated.

Treatment

Conservative Management

Conservative care is tailored to the severity of the cavus deformity. Mild deformities may only require a softer-soled shoe. Significant clawing of the lesser toes may require an extra-depth shoe. A custom-made Plastazote liner with a built-in arch support helps decrease the stress on the metatarsal heads. A significant motor deficit may require an AFO to stabilize the ankle. Most cases of cavus foot can be managed with conservative modalities.

Surgical Treatment

Surgical treatment for the cavus foot is aimed at correcting the site of the deformity. The most frequent pattern consists of plantar flexion of the first metatarsal, contracture of the plantar fascia, and varus deformity of the calcaneus. These problems respond to release of the plantar fascia, dorsiflexion osteotomy of the first and perhaps second metatarsal, and lateral closing-wedge osteotomy (Dwyer procedure) of the calcaneus to correct the varus deformity. Fusion of the joints is avoided to maintain as much flexibility of the foot as possible (Figure 8–45).

A more severe deformity involving dorsiflexion of the calcaneus can be treated with sliding osteotomy of the calcaneus (Samilson procedure), correcting any varus deformity with a lateral closing-wedge osteotomy and releasing the plantar fascia (Figure 8–46). Forefoot deformity is treated with osteotomy of the first and sometimes second metatarsal. In some patients, transfer of the peroneus longus tendon into the brevis and lengthening of the posterior tibial tendon provides dynamic muscle balance for the foot.

Severe deformities not amenable to procedures that retain joint motion require triple arthrodesis. A Siffert beak-type triple arthrodesis corrects the deformity because the navicular is mortised under the head of the talus to help reduce the elevation of the longitudinal arch (Figure 8–47). A first metatarsal osteotomy may need to be added to the procedure as well.

The lesser toes may have either fixed or flexible claw toe deformities. Flexible deformity often responds to release of the extensor tendons and a Girdlestone flexor tendon transfer. If a fixed deformity is present, a DuVries phalangeal condylectomy corrects the hammer toe, followed by extensor tendon release and the Girdlestone procedure.

Hyperextension of the first metatarsophalangeal joint is corrected by interphalangeal arthrodesis of the hallux and transfer of the extensor hallucis longus tendon into the neck of the first metatarsal (Jones procedure).

Orthotic devices are used to redistribute stresses on the foot as it makes contact with the ground and to accommodate for abnormal function of defective muscles or ligaments. This is achieved by controlling the posture of the foot and padding certain areas to relieve pressure and provide increased comfort for the foot. Orthoses are also used to limit motion in arthritic joints, making them less painful. The orthotic device may be attached to the sole of the shoe, may be inserted inside the shoe as an insole, may cup the foot (UCBL insert), or may extend across the ankle to hold the entire foot and ankle in place (AFO).

Orthotic Shoe Sole Devices

A variety of heel and sole corrections are available to accommodate foot postural abnormalities. A medial or lateral heel or sole wedge (or a combination of both) can help control excessive pronation or supination from weak tendons, ligamentous instability, or fixed deformities. A wide heel is used to increase the stability of the subtalar joint. A rocker sole helps stabilize the forefoot in the case of a fracture or arthritis and also aids a patient with an ankle fusion to allow a more normal gait pattern.

Orthotic Insole Devices

Insole orthotic devices can be used for flexible deformities to alter the posture of the foot and for fixed deformities to redistribute stress. The simplest device is a soft liner for a shoe or boot made out of a high-density foam material. Other simple orthoses include a soft felt pad to relieve pressure on the metatarsal heads or a combination of materials to produce a more rigid support to help control a forefoot deformity such as forefoot varus or valgus deformity. Orthotic devices take up space in the shoe, and the patient may need a larger or deeper shoe.

University of California Biomechanics Laboratory Insert

The principle of the UCBL insert is to correct a foot deformity such as flatfoot by stabilizing the calcaneus in neutral position and molding the orthosis to block abduction of the forefoot. Posting along the medial aspect may compensate for forefoot varus. In theory, this orthotic device is excellent for controlling the rearfoot and forefoot, but two caveats apply to the use of this device. The first is that the foot must be flexible because correction of a rigid deformity is impossible. The second is that a bony prominence can chafe against the polypropylene material, resulting in pain or skin breakdown over the prominence.

Ankle-Foot Orthosis

An AFO is a molded polypropylene device that passes along the posterior aspect of the calf and then onto the plantar aspect of the foot to the metatarsal heads. Alterations are made in a variety of ways to accommodate the patient's problem. Ankle problems such as arthrosis or dorsiflexion weakness require adequate rigidity to eliminate ankle joint motion. An orthosis for a subtalar joint problem should have enough flexibility to provide ankle joint motion but must be rigid enough to immobilize the subtalar joint. When the problem involves the transverse tarsal joint, the AFO can be fabricated to permit some ankle joint motion but maintain immobilization of the transverse tarsal joint area, usually by blocking abduction of the forefoot. When managing tarsometatarsal arthritis, the footpiece is carried to the tips of the toes. Again, a significant fixed bony deformity results in pressure points, making fitting of the device difficult. If the patient has loss of sensation, careful construction and padding are essential to minimize the risk of ulcers forming over a bony prominence. In cases of marked instability or discomfort, an anterior shell can be added to the AFO, and the brace is extended proximally to create a patellar tendon bearing surface.

Double Upright Orthosis

The double upright orthosis with a hinged ankle may be used when individuals require stability but are engaged in physically demanding activities. The double upright orthosis is somewhat more cumbersome than the AFO but provides rigid immobilization. The hinge mechanism of the ankle joint may be changed, depending on the nature of the patient's problem. The ankle joint can be free, which allows dorsiflexion and plantar flexion to occur, or it can be fixed to prevent plantar flexion past 90 degrees. This brace can be modified with a spring load to provide dorsiflexion for the patient with dropfoot resulting from paralysis but should not be used for the patient with spasticity because it may accentuate the spasticity.

Prescriptions for Orthotic Devices

The following are typical prescriptions for orthotic devices.

Metatarsalgia or Atrophy of Plantar Fat Pad

Treatment

A full-length well-molded orthosis for metatarsal arch support is used to relieve pressure under the metatarsal heads. Soft insole material should be used.

Explanation

In the treatment of metatarsalgia or atrophy of the plantar fat pad, a full-length orthosis is needed that is molded to the plantar aspect of the foot and built up just proximal to the metatarsal heads to relieve pressure on them. The material should be soft to provide extra cushioning for the foot.

Ruptured Posterior Tibial Tendon with Moderately Severe Flexible Flatfoot Deformity

Treatment

AFO with trim-line cut to permit 30% ankle joint motion is molded to reestablish the longitudinal arch and built up on the lateral aspect of the footpiece to block abduction of the forefoot.

Explanation

With a moderately advanced flexible flatfoot deformity, an in-shoe orthotic device alone does not provide sufficient support; the AFO is needed to provide adequate stability. Some ankle joint motion is included, which makes ambulation more comfortable for the patient. The longitudinal arch is molded to support the foot in a plantigrade position, and the lateral aspect of the AFO is built up to prevent the forefoot from moving into an abducted position. By blocking abduction, the amount of pressure needed beneath the longitudinal arch to prevent it from collapsing is decreased.

Posterior Tibial Tendon Insufficiency with Mild Flatfoot Deformity and 5 Degrees of Forefoot Varus Deformity

Treatment

Use a well-molded longitudinal arch support, with a 5-degree varus post and a 3-degree medial heel lift.

Explanation

Insufficiency of the posterior tibial tendon that has not produced a significant foot deformity can be treated with a well-molded longitudinal arch support. The 5-degree varus forefoot post compensates for the fixed forefoot varus, and the 3-degree heel lift likewise helps tilt the hindfoot from valgus deformity closer to neutral position.

Dropfoot Secondary to Peroneal Nerve Injury

Treatment

An AFO with a full footpiece is molded to the longitudinal arch.

Explanation

A dropfoot secondary to a peroneal nerve injury responds well to an AFO with a full footpiece. The footpiece supports the toes so they do not drop and makes it easier for the patient to put on shoes.

Diabetic Neuropathy with Clawfoot Deformity

Treatment

An extra-depth shoe with a molded Plastazote liner is backed with a Pelite material.

Explanation

The patient with clawfoot deformity requires a shoe that has extra height in the toe box. The extra-depth shoe provides enough room for the toes, so they do not chafe against the top of the shoe. The molded Plastazote liner is an excellent means of providing full contact to the plantar aspect of the foot. Plastazote has a tendency to bottom out, as it were, and by backing the material with a Pelite liner or some comparable material, the life expectancy of the Plastazote is extended significantly.

Ankle ligament injuries represent the most common musculoskeletal injury; therefore, accurate assessment and treatment of these injuries are important. The lateral collateral ligament complex is most commonly injured, but damage to other important structures around the ankle joint should not be overlooked, as discussed in this section.

Functional Anatomy

The lateral collateral ligament structure of the ankle consists of three distinct ligamentous bands: the anterior and posterior talofibular ligaments (ATFL and PTFL) and the calcaneal fibular ligament (CFL).

When the ankle joint is in plantar flexion, the ATFL is positioned in line with the fibula and therefore placed under stress with an inversion injury and will be damaged. Conversely, when the ankle joint is in dorsiflexion, the CFL is positioned in line with the long axis of the fibula and is therefore subject to injury. If the applied stress is severe, both the ATFL and the CFL may be torn, no matter the position of the ankle joint. The syndesmosis ligament complex tethers the tibia and fibula together and is injured by an external rotational force to the foot. The deltoid ligament is the sole medial stabilizer of the ankle joint. An isolated deltoid ligament injury can occur with an eversion or external rotation force on the foot. The deltoid ligament can also sustain injury in conjunction with a syndesmosis ligament injury, with lateral ankle sprains, or with a concomitant fibula fracture (known as a Maisonneuve fracture).

Clinical Findings

Classification

Lateral collateral ankle ligament injuries are divided into three degrees of severity. A grade I sprain is confined to the ATFL and demonstrates no instability. A grade II sprain involves injury to both the ATFL and CFL, with mild laxity of one or both ligaments. A grade III sprain involves injury and significant laxity of both the ATFL and CFL.

Symptoms and Signs

A past history of injuries of the ankle and problems with chronic ankle ligament instability should be ascertained. A careful physical examination is important to evaluate the degree of involvement of each ligament and to rule out injury to any adjacent bony or soft-tissue structures. The ATFL, PTFL, CFL, and syndesmosis ligaments are palpated for tenderness. To rule out fractures, pain should be elicited in the area of the distal fibula, the anterior process of the calcaneus, the lateral process of the talus, and at the base of the fifth metatarsal. Other areas where an injury must be ruled out include the subtalar joint and the peroneal tendon sheath.

A patient with significant medial joint pain with or without lateral ligament pain should be evaluated for an injury to the deltoid ligament complex, the posterior tibial tendon, and the medial talar dome. Assessment of ankle ligament stability requires clinical and radiographic stress examinations. To perform an anterior drawer maneuver, which tests stability of the ATFL, the ankle is placed in 30 degrees of equinus, and the ankle is pulled in an anterior and slightly internally rotated direction (Figure 8–48). A feeling of subluxation is present if a significant ligament injury has occurred. A talar tilt maneuver is performed by placing an inversion stress on the heel. With the foot in plantar flexion, this tests the stability of the ATFL. With the foot in neutral or dorsiflexion, a talar tilt maneuver tests the stability of the CFL. If clinical instability is suggested by either maneuver, radiographic confirmation can be performed, with comparison to the unaffected ankle.

Deltoid ligament insufficiency may cause a feeling of instability and giving way, affecting the medial aspect of the ankle joint. Stress examination is performed by pulling the foot laterally and into valgus while stabilizing the distal tibia.

Injury to the syndesmosis ligament complex is suspected if the region between the distal anterior tibia and fibula is tender to palpation. If extensive swelling is present more than 2 cm proximal to the ankle joint, syndesmosis rupture is a strong possibility. Pain elicited by squeezing the tibia and fibula together in the midcalf is diagnostic of a syndesmosis ligament tear. A syndesmosis ligament injury is also suspected if external rotation of the foot is painful or if lateral translation of the talus in the ankle mortise occurs with direct lateral force on the foot.

Imaging Studies

Standard anteroposterior, lateral, and oblique radiographs of the ankle should be obtained to rule out a fracture of the fibula, talus, or calcaneus. If ligament laxity is suggested on clinical examination, stress radiographs should be obtained. An anteroposterior view is taken while a talar tilt maneuver is performed, and a lateral view is taken while an anterior drawer maneuver is performed. More than 10 degrees of tilt and more than 5–7 mm of anterior drawer are considered abnormal.

If a syndesmosis ligament injury is suspected, careful attention must be paid to the joint spaces to rule out widening of the ankle mortise. If instability is suspected, a stress radiograph is performed by externally rotating the foot with the tibia held still.

MRI or CT scan may be helpful in some instances if there is a high index of suspicion for an accompanying injury. Osteochondral injuries to the talus should be ruled out with an MRI scan. If a talus or calcaneus fracture is suspected, either MRI or CT scan may be of benefit.

Treatment

Conservative Management

Acute grade I ligament tears are treated with a lateral stabilizing ankle brace, ice, and avoidance of painful activities. Immediate full weight bearing is allowed, as are non–weight-bearing physical activities, such as bicycling and swimming. The brace can be discontinued in 1 month.

Grade II ligament tears are treated with protected weight bearing and a lateral stabilizing ankle brace. The patient can begin non–weight-bearing exercise (stationary bicycle) after 7 days, along with peroneal strengthening exercises. Weight-bearing exercise (jogging) may resume after 2–4 weeks.

In a grade III ligament tear, the ankle is immobilized with a removable walking cast for 3–4 weeks. This is followed by a period of physical therapy consisting of ROM exercises, peroneal strengthening, and proprioception training using a biomechanical ankle platform system (BAPS) board.

Treatment of isolated deltoid ligament sprains depends on the severity of the injury and is similar to lateral ligament injuries. Mild injuries can be treated with immediate mobilization and rapid return to activity, whereas more severe injuries should be casted for 3–4 weeks.

Syndesmosis ligament tears, if mild, can be treated with weight bearing in a cast or brace and close follow-up to assess for widening of the ankle joint mortise. If the interosseous membrane is damaged, as evidenced by massive swelling of the leg proximal to the ankle joint, treatment depends on the radiographic appearance of the ankle. If the mortise has not widened, the patient is kept on a non–weight-bearing regimen in a cast for 6 weeks, with close radiographic follow-up. If initial or follow-up radiographs show a widened mortise, the patient requires surgical repair of the syndesmosis ligaments with temporary screw placement until the ligaments heal.

Surgical Treatment

The surgical treatment of an acute ligamentous injury is indicated only for the occasional elite athlete. Most ligamentous injuries, even grade III sprains, heal sufficiently with no significant disability if properly treated, as just described. However, even less severe ankle sprains may cause chronic pain or functional instability if left untreated.

The indication for a lateral ligament reconstruction is functional ligament instability. A patient with ligament instability complains of recurrent sprains that occur with sports activities or even with activities of daily living, despite 4–6 months of physical therapy and use of a lateral stabilizing brace. A patient with functional ligament instability also complains of difficulty walking on uneven ground. This history must be found in conjunction with physical examination findings of ligament instability.

Although many lateral ankle reconstruction procedures are described for chronic lateral ankle ligament instability, a Broström repair is generally the procedure of choice. The Broström procedure is a soft-tissue ligamentous repair in which the ATFL and CFL are plicated and reattached to their anatomic positions (Figure 8–49). The repair is reinforced by bringing up a portion of the inferior extensor retinaculum. The Broström procedure is highly effective and has lower morbidity than other procedures that harvest the peroneus brevis tendon. In patients who have severe and long-standing laxity or have failed a Broström repair, revision surgery with an allograft or autograft tendon is indicated.

Chronic lateral ankle pain following an ankle sprain may be caused by a previously undiagnosed condition rather than chronic ankle instability. The differential diagnosis for chronic ankle pain is similar to that following an acute injury and also includes subtalar joint instability, subtalar joint chondral damage or synovitis, and dislocating or torn peroneal tendons. Impingement of scar tissue in the lateral gutter between the talus and fibula may also cause chronic lateral ankle pain. In addition to a careful physical examination, an MRI or CT scan may be helpful for distinguishing among these possible causes of pain.

Surgical treatment may help relieve symptoms of chronic lateral ankle pain, once an accurate diagnosis is made. Chondral or osteochondral fractures involving the ankle or subtalar joints can be treated with arthroscopic or open debridement or pinning. Subtalar joint instability is addressed with a Broström procedure. A fracture of the anterior or lateral process of the talus is either removed if it is small or fixed if it is a large fragment. Tears or dislocations of the peroneal tendons are repaired or stabilized. Scar tissue in the lateral gutter can be treated with arthroscopic debridement.

Chronic instability of the deltoid ligament or syndesmosis ligament is uncommon but can occur after an untreated injury. Diagnosis of either condition is made with stress radiographs. Treatment usually requires a free tendon graft to reconstruct the damaged ligament, with the addition of internal fixation for chronic syndesmosis tears.

Arthroscopy is an important tool for use in diagnosis and treatment of foot and ankle disorders. With developments in instrumentation, more ankle joint conditions can be treated arthroscopically. Arthroscopy of the subtalar joint is also now an accepted method for diagnosing and treating some subtalar joint abnormalities.

Advantages of Ankle Arthroscopy over Ankle Arthrotomy

Arthroscopy of the ankle joint offers distinct advantages over open exploration of the ankle. The entire joint can be visualized using the arthroscope, including the lateral and medial gutters and the posterior aspect of the joint. Dynamic studies can be performed to stress ligaments or identify areas of soft-tissue or bony impingement. Furthermore, the low morbidity of arthroscopy allows rapid rehabilitation.

Indications

Table 8–4 lists the indications for ankle joint arthroscopy. In addition, arthroscopic examination can be used as a diagnostic tool in some instances when the precise cause of ankle pain remains in question.