Upper Extremity Amputations and Disarticulations
Although microsurgical replantation techniques have reduced the incidence of hand amputations, for many patients, replantation is still not feasible or results in failure. There is considerable controversy about the best treatment for any given hand injury, and the optimal treatment takes into consideration the injured patient's occupation, hobbies, skills, and hand of dominance. The hand is a highly visible and important part of body image. Many patients with partial hand amputations can benefit tremendously from using a cosmetic partial hand prosthesis.
Fingertip injuries occur frequently, and fingertip amputation is the most common type of amputation. The treatment of choice usually depends on the geometry of the defect and whether or not bone is exposed. Although a large variety of local flap procedures are used to cover defects of different shapes and sizes, there is also a growing understanding that allowing secondary healing of fingertip injuries is the treatment least prone to complications in adults as well as in children. Even if bone is exposed, simply rongeuring back the exposed bone proximal to the soft-tissue defect and allowing secondary healing can give excellent results. The amount of the bone that can be removed is limited because at least a third of the distal phalanx must be left intact to prevent a hook deformity of the nail.
Two problems frequently result from fingertip amputations: cold intolerance and hypersensitivity. Overall, regardless of which treatment is chosen, approximately 30–50% of patients experience these problems. One criticism of the many local flap procedures used to obtain coverage and primary wound healing is that all of them involve incising and advancing uninjured tissue, which extends the area of scarring and damages the fine branches of the digital nerves. Newer studies suggest that the incidence of cold intolerance and hypersensitivity may be lower with secondary healing than with skin grafts or local flaps.
The thumb, with its unique range of motion, plays the major role in all three prehensile activities of the hand: palmar grip, side-to-side pinch, and tip-to-tip pinch. Amputation of the thumb can result in the loss of virtually all hand function. Thumb amputations can involve (1) the distal third of the thumb (ie, distal to the interphalangeal joint), (2) the middle third of the thumb (ie, from the metacarpophalangeal joint to the interphalangeal joint), or (3) the proximal third of the thumb.
Thumb amputation of the distal third allows the patient to retain a tremendous amount of thumb function. Cold intolerance and hypersensitivity are frequent problems, as noted in the previous discussion of fingertip amputations. Treatment of distal third injuries should allow secondary healing of the thumb or should use relatively uncomplicated techniques for coverage.
Thumb amputation in the middle third is more complicated. The issues here are length, stability, and sensate skin coverage. More aggressive procedures may well be warranted and may consist of cross-finger flaps, volar advancement flaps, neurovascular island flaps from the dorsal index finger (radial nerve) or volar middle finger (median nerve), bone lengthening, or web space deepening.
Thumb amputation in the proximal third has a devastating impact on hand function. Local reconstruction for this degree of loss is not generally successful. Pollicization of another digit, a toe-to-hand transfer, or other complicated surgical techniques, such as osseointegration of a prosthesis, may be indicated to restore function.
Jönsson S, Caine-Winterberger K, Brånemark R: Osseointegration amputation prostheses on the upper limbs: methods, prosthetics and rehabilitation. Prosthet Orthot Int
Isolated amputation of a lesser digit can cause a variety of functional and cosmetic problems. Replantation of digits can often be performed but must be individualized to the patient, as function is often acceptable with an amputation and amputation will allow a quicker return to activities. Digit amputations distal to the insertion of the sublimis flexor tendon retain active flexor tendon activity and maintain useful metacarpophalangeal joint flexion. The long flexor tendon should not be sewn to the extensor tendon because it limits the excursion of both tendons and definitely limits the function of the remaining digits.
Amputations proximal to the sublimis tendon insertion retain approximately 45 degrees of proximal phalanx flexion at the metacarpophalangeal joint through the action of the intrinsic muscles. This is usually enough to keep small objects from falling through the defect and to allow the residual finger to participate to some degree in grip. If the patient uses a cosmetic finger prosthesis and wears a ring to cover the proximal edge of the prosthesis, the amputation is almost unnoticeable.
The index finger participates principally in side-to-side and tip-to-tip pinch with the thumb. After an amputation of the index finger at the metacarpophalangeal joint, the middle finger assumes this important role. The residual second metacarpal can interfere with side-to-side pinch between the thumb and the middle finger, however. Converting this amputation to a ray amputation often can improve function and cosmesis, but the drawback is that it also narrows the width of the palm and can decrease grip and torque strength significantly. Surgical decisions must be individualized, but the second metacarpal should probably be retained if the patient uses hand tools extensively, as does a carpenter or machinist.
Amputation of the middle or ring finger at the metacarpophalangeal joint can make it difficult for the patient to hold small objects because they tend to fall through the defect. Full ray resection can narrow the central defect and occasionally improve function, but narrowing the palm can decrease grip and torque strength.
Amputation of the small finger at the metacarpophalangeal joint is often cosmetically unacceptable because of the abrupt and noticeable change in contour of the hand. Although converting a fifth digital amputation to a ray amputation by including the metacarpal can improve cosmesis, it also narrows the width of the palm and can decrease grip and torque strength. Surgical decisions must be based on individual factors and concerns.
Amputations through the carpus are generally discouraged. Most surgeons believe the result to have no real advantages over a wrist disarticulation or transradial amputation. There are isolated reports of patients valuing the little bit of wrist flexion and extension that allows them to hold objects against their body and to stabilize objects for two-handed grasp. The flexor and extensor carpi radialis and ulnaris tendons must be reattached to provide this limited motion. The prosthetic options are less standard and generally considered to be less functional than the traditional transradial designs.
Carpus amputations should probably be considered in bilateral cases. Although rare, more patients sustaining tissue loss from ischemia are seen in the intensive care unit after prolonged resuscitations and the use of vasopressors. Without the vasopressors, these patients would die. Unfortunately, part of the body's response to these lifesaving medications can be to shunt blood flow from the distal extremities, resulting in demarcation and dry gangrene in the hands and feet. Just as in frostbite, if infection is not present, it is worthwhile to delay any surgical intervention and allow adequate time for tissue demarcation and recovery. Partial hand amputation is occasionally necessary, and if required, the carpus level should be considered.
Wrist disarticulation continues to be controversial. Proponents frequently argue that it has two advantages over the shorter transradial amputation: It retains the distal radioulnar joint, which preserves more forearm rotation, and it retains the distal radial flare, which dramatically improves prosthetic suspension. Volar and dorsal fish-mouth incisions are usually best, and removal of the radial and ulnar styloids can prevent painful pressure points. Tenodesis of the major forearm motors stabilizes the muscle units and thereby improves physiologic and myoelectric performance.
Opponents of wrist disarticulation argue that prosthetic substitution after this procedure is slightly more complicated than it is after a standard transradial amputation. The prosthetic socket is more difficult to fabricate because of the bone contours. Conventional wrist units add too much length to the prosthetic arm after wrist disarticulation and therefore cannot be used. The terminal device for a wrist disarticulation also needs to be modified because of length. Myoelectric prostheses are difficult to fit because there is less space to conceal the electronics and power supply.
Despite these prosthetic concerns, wrist disarticulation patients are often excellent upper extremity prosthetic users. Some patients with an unsatisfactory hand can gain improved function by undergoing a wrist disarticulation and using a standard prosthesis. This decision must be individualized and based on contributory factors such as severity of tissue loss, pain, functional requirements, and the patient's body image.
The transradial amputation is extremely functional, and successful prosthetic rehabilitation and sustained use are achieved in 70–80% of patients who undergo amputation at this level. Forearm rotation and strength are proportional to the length retained. Surgical incisions are best with equal volar and dorsal flaps. A myodesis should be performed to prevent a painful bursa, facilitate physiologic muscular suspension, and allow for myoelectric prosthetic use. An extremely short transradial residual limb requires the use of a Muenster-type socket, which molds up around the humeral condyles for added suspension. Occasionally, side hinges and a humeral cuff are required to achieve suspension of the prosthesis. Both of these types of suspension preserve elbow flexion and extension but limit rotation.
The value of preserving the elbow joint cannot be overemphasized. Skin grafts and even composite grafts should be considered to retain the tremendous functional benefit of an elbow with some active motion. Even a limited range of elbow motion can be useful, and an ingeniously designed, geared step-up elbow hinge can convert a limited active range of elbow motion to an improved prosthetic ROM. Although body-powered prostheses are extremely functional at the transradial level of amputation, this level is also the most successful level at which to use myoelectric devices.
The Krukenberg kineplastic operation transforms the transradial amputation stump into radial and ulnar digits that are capable of strong prehension and have excellent manipulative ability because of retained sensation on the “fingers” of the forearm. The operation should not be performed as a primary amputation.
The Krukenberg amputation can be performed as a secondary procedure in a transradial amputee who has a residual limb of at least 10 cm from the tip of the olecranon, an elbow flexion contracture of less than 70 degrees, and good psychological preparation and acceptance. In this case, the amputee can become completely independent in daily activities because of the retained sensory ability of the pincers as well as the quality of the grasping mechanism (Figure 11–6). The Krukenberg amputation traditionally was indicated for blind patients with bilateral below-elbow amputations, but it also may be indicated at least unilaterally in bilateral below-elbow amputees who are able to see and in those who have limited access to prosthetic facilities.
A patient with bilateral Krukenberg hands demonstrates bimanual dexterity in sharpening a pencil. (Reproduced, with permission, from Garst RJ: The Krukenberg hand. J Bone Joint Surg Br 1991;73:385.)
A conventional prosthesis can be worn over the Krukenberg forearm, and myoelectric devices can be adapted to use the forearm motion. The major disadvantage is the appearance of the arm, which many people consider grotesque and do not accept. As society continues to become more understanding and accepting of disabled individuals, concerns about appearance may diminish. Intensive preoperative preparation and counseling are mandatory.
Elbow disarticulation can be a satisfactory amputation level and has the advantage of retaining the condylar flare to improve prosthetic suspension and allow for the transfer of humeral rotation to the prosthesis. The longer lever arm improves strength. The disadvantage is in the design of the prosthetic elbow hinge. An outside hinge is bulky and hard on clothing, whereas the conventional elbow unit provides a disproportionately long upper arm and short forearm. Whether the advantages of the elbow disarticulation outweigh the disadvantages remains controversial. Surgically, volar and dorsal flaps work best, and myodesis of the biceps and triceps tendons are needed to preserve the distal muscle attachments.
When transhumeral amputation is performed, efforts should be made to retain as much as possible of the bone length that has suitable soft-tissue coverage. Even if only the humeral head remains and no functional length is salvageable, an improved shoulder contour and cosmetic appearance results. Myodesis helps preserve biceps and triceps strength, prosthetic control, and myoelectric signals. In most cases of transhumeral amputation, an immediate postoperative prosthesis and rigid dressings can be used successfully. Physical therapy should focus on proximal joint and muscle function. Because the terminal prosthetic device is usually controlled by active shoulder girdle motion, early prosthetic use and therapy can prevent contracture and maintain strength.
Prosthetic suspension traditionally was incorporated in the body-powered harness, which can be somewhat uncomfortable. Among the alternative techniques are humeral angulation osteotomy (rarely used), socket-suction suspension, and the newer elastomeric roll on locking liners. Many prosthetic options are available for the transhumeral amputee. One option is a prosthesis that is totally body powered. Another is a hybrid prosthesis that uses myoelectric control of one component (either the terminal device or the elbow device) and body-powered control of the other. The transhumeral prosthesis is heavy, often considered slow, and requires much mental concentration to use effectively. These issues lead many unilateral transhumeral amputees to choose not to wear a prosthesis at all or to wear only a lightweight cosmetic prosthesis for special occasions.
Transhumeral amputation is sometimes elected to manage a dysfunctional arm following a severe brachial plexus injury. The advantages of amputation are that it unloads the weight from the shoulder and scapulothoracic joints and eliminates the problem of having a paralyzed arm that gets in the way and hinders body function. The decision to undertake shoulder arthrodesis in combination with transhumeral amputation is controversial and should be made on an individualized basis. Investigators who compared two groups of patients with transhumeral amputation because of brachial plexus injury—one group without shoulder arthrodesis and one group with it—found a somewhat better return-to-work rate in the group without shoulder arthrodesis. Prosthetic expectations in these patients should be limited because prosthetic fitting adds weight to a dysfunctional shoulder girdle, often defeating one of the original goals of the amputation.
Shoulder Disarticulation and Scapulothoracic (Forequarter) Amputation
The performance of shoulder disarticulation (Figure 11–7) or scapulothoracic amputation (Figure 11–8) is rare. When either operation is performed, it is usually in cases of cancer or severe trauma. Either operation results in a loss of the normal shoulder contour and causes the patient difficulty because clothing does not fit well. Saving the humeral head, if possible, can improve the contour of a shoulder disarticulation tremendously. The scapulothoracic amputation, usually performed for proximal tumors, removes the arm, scapula, and clavicle. Dissection often extends into the neck and into the thorax.
Elaborate myoelectric prostheses are available for patients but are expensive, heavy, and require intensive maintenance. Body-powered prostheses are also heavy, hard to suspend comfortably, and difficult to use. Most patients request prosthetic help for improved cosmesis and fitting of clothes. Often a simple soft mold to fill out the shoulder meets these expectations and is an alternative to a full-arm cosmetic prosthesis.
Postural Abnormalities after High Upper Extremity Amputation
Normally, the weight of the arm and the muscle activity associated with shoulder and arm function keep the shoulders appropriately level. Unilateral hypertrophy of an upper limb, including the shoulder girdle, occurs in certain occupations and is also seen in some sports. Some people are born with a degree of asymmetry of their shoulders, which is a relatively minor postural abnormality and does not require special clothing.
When the arm is removed and the clavicle and scapula remain, the muscles elevating the shoulder girdle are unopposed by both the weight of the arm and those muscles that pass across the shoulder and tend to depress the shoulder and arm. The consequence of this imbalance is an upward elevation described as “hiking” of the shoulder girdle. This high shoulder tends to accentuate the cosmetic loss, even when the individual is wearing a cosmetic shoulder filler or a cosmetic limb. Abnormal shoulder elevation can be countered by corrective exercises beginning as soon as they can be tolerated after the amputation. The wearing of a prosthesis with its dependent weight also diminishes shoulder hike. In most circumstances, the shoulder girdle elevation is inevitable; however, its degree can be minimized by appropriate physical measures.
Removal of the entire upper limb in the growing skeleton can result in a scoliosis of the spine. Muscular imbalance is considered to be the cause of the deformity. It may be seen to a slighter degree in the adult but is primarily confined to the growing skeleton. The combined postural deformity of upper dorsal spine scoliosis and elevation of the shoulder girdle produces asymmetry of the head and neck on the trunk, with the head appearing to be placed asymmetrically as the person stands.
In general, no corrective splinting or orthotic device can successfully counteract the postural changes associated with shoulder-level amputation. Neck and shoulder-girdle exercises offer the most effective prophylaxis and treatment. The postural deficits are particularly evident with forequarter amputation. Soft, light polyurethane cosmetic restoration, either as part of a cosmetic prosthesis or separately used with the empty sleeve, counters to some degree the unsightly upper body contour.
Hand transplantation and the suppression of rejections are now technically possible. Approximately 49 documented cases of hand transplantation have been performed with varying degrees of success. Protective sensory function is reported for all patients, with discriminative sensation in 82% of patients, while motor function was adequate to perform most activities. However, of the 33 patients (16 bilateral), there was one death and seven graft removals. The potential benefits for the amputee are certainly many, but they must be balanced against the real risks. In general, skin, muscle, and bone marrow appear to reject earlier and more aggressively than bone, cartilage, or tendon. Preventing this rejection is an ongoing and lasting issue, with real consequences for the individual's health and life expectancy. The current immunosuppressive drugs needed to prevent rejection of a composite hand transplant include toxic side effects, opportunistic infections, and increase in malignancies. The visibility of the hand, as compared to the internal transplanted organs, allows detection of rejection much more readily. Advances in immunology are permitting less aggressive immunoregulation instead of immunosuppression, which may improve the feasibility of this procedure.
Also, the real psychological impact following hand and other organ transplantation should not be underestimated. One study examining the issues 5 years following heart transplant showed a significant increase in emotional issues such as irritability, depression, and low self-esteem. Even for a patient with no preexisting psychological issues, living with a hand transplantation, which remains constantly in view, may not be easy.
Baumeister S, Kleist C, Dohler B, et al: Risks of allogeneic hand transplantation. Microsurgery
Crandall RC, Tomhave W: Pediatric unilateral below-elbow amputees: retrospective analysis of 34 patients given multiple prosthetic options. J Pediatr Orthop
Petruzzo P, Lanzetta M, Dubernard JM, et al: The International Registry on Hand and Composite Tissue Transplantation. Transplantation
Schatz RL, Rosenwasser MP: Krukenberg kineplasty: a case study. J Hand Ther
Scheker LR Becker GW: Distal finger replantation. J Hand Surg Am
Sebastin SJ, Chung KC: A systematic review of the outcomes of replantation of distal digital amputation. Plast Reconstr Surg
Shores JT, Brandacher G, Schneeberger S, et al: Composite tissue allotransplantation: hand transplantation and beyond. J Am Acad Orthop Surg
Wilkinson MC, Birch R, Bonney G: Brachial plexus injury: when to amputate? Injury
Lower Extremity Amputations and Disarticulations
Toe amputations can be performed with side-to-side or plantar-to-dorsal flaps to use the best available soft tissue. The bone should be shortened to a level that allows adequate soft-tissue closure without tension.
In great toe amputations, if the entire proximal phalanx is removed, the sesamoids can retract and expose the keel-shaped plantar surface of the first metatarsal to weight bearing. This often leads to high local pressure, callous formation, or ulceration. The sesamoids can be stabilized in position for weight bearing by leaving the base of the proximal phalanx intact or by performing tenodesis of the flexor hallucis brevis tendon.
An isolated amputation of the second toe commonly results in severe hallux valgus deformity of first toe (Figure 11–9). This situation may be prevented by amputation of the second ray or by fusion of the first metatarsal and phalanx. In the shorter toe amputations at the metatarsophalangeal joint level, transferring the extensor tendon to the capsule may help elevate the metatarsal head and maintain an even distribution for weight bearing. Prosthetic replacement is not required after toe amputations.
Severe hallux valgus deformity occurring after isolated second toe amputation.
A ray amputation removes the toe and all or some of the corresponding metatarsal. Isolated ray amputations can be durable. Multiple ray amputations, however, especially in patients with vascular disease, can narrow the foot excessively. This increases the amount of weight that must be borne by the remaining metatarsal heads and can lead to new areas of increased pressure, callous formation, and ulceration. Surgically, it is often difficult to achieve primary closure of ray amputation wounds because more skin is usually required than is readily apparent. Instead of closing these wounds under tension, it is usually advisable to leave them open and allow for secondary healing.
The fifth ray amputation is the most useful of all the ray amputations. Plantar and lateral ulcers around the fifth metatarsal head often lead to exposed bone and osteomyelitis. A fifth ray amputation allows the entire ulcer to be excised and the wound to be closed primarily (Figure 11–10). In general, for more extensive involvement of the foot, a transverse amputation at the transmetatarsal level is more durable. Prosthetic requirements after ray amputations include extra-depth shoes with custom-molded insoles. The insole should include a metatarsal pad that loads the shafts of the metatarsal and unloads some of the pressure at the metatarsal heads.
Fifth ray amputation for fifth metatarsal head ulcer.
The transmetatarsal and Lisfranc amputations are reliable and durable. The Lisfranc amputation is actually a disarticulation just proximal to the metatarsals where the cuneiform and cuboid bones are retained. Surgically, a healthy, durable soft-tissue envelope is more important than a specific anatomic level of amputation, so the length of bone to be removed should be based on the ability to perform soft-tissue closure without tension. A long plantar flap is preferable, but equal dorsal and plantar flaps work well, especially for transmetatarsal amputation in the treatment of metatarsal head ulcers (Figure 11–11).
Transmetatarsal amputation with Achilles tendon lengthening.
Muscle balance around the foot should be carefully evaluated preoperatively, with specific attention to tightness of the heel cord and strength of the anterior tibial, posterior tibial, and peroneal muscles. Midfoot amputations significantly shorten the lever arm of the foot, so lengthening of the Achilles tendon should be done if necessary. Tibial or peroneal muscle insertions should be reattached if they are released during bone resection. For example, if the base of the fifth metatarsal is resected, the peroneus brevis tendon should be reinserted into the cuboid bone. In patients with vascular disease, this can be performed with a minimal amount of dissection to prevent further compromise of the tissues.
Postoperative casting prevents deformities, controls edema, and speeds rehabilitation. Prosthetic requirements can vary widely. During the first year following amputation, many patients benefit from the use of an ankle-foot orthosis (AFO) with a long footplate and a toe filler. To prevent an equinus deformity from developing, patients should be advised to wear the orthosis except when taking a bath or shower. Later, the use of a simple toe filler combined with a stiff-soled shoe may be adequate. Cosmetic partial foot prostheses are also available.
A Chopart amputation removes the forefoot and midfoot and saves only the talus and calcaneus. Rebalancing procedures are required to prevent equinus and varus deformities. Achilles tenotomy, transfer of the anterior tibial or extensor digitorum tendons, and postoperative casting are all usually necessary. Although tendon transfer to the talus was previously recommended, transfer to the calcaneus is now done to minimize varus positioning. Beveling the inferior, anterior surface of the calcaneus can remove a potential bone pressure point.
Two other types of hindfoot amputations are the Boyd and the Pirogoff amputations. The Boyd procedure consists of a talectomy and calcaneal-tibial arthrodesis after forward translation of the calcaneus. The Pirogoff procedure consists of a talectomy with calcaneal-tibial arthrodesis after the vertical transection of the calcaneus through the midbody and a forward rotation of the posterior process of the calcaneus under the tibia. These two types of hindfoot amputations are done mostly in children to preserve length and growth centers, prevent heel pad migration, and improve socket suspension.
Studies in which various procedures in children are compared showed that a hindfoot amputation results in better function than a Syme amputation (see section on Syme amputation) in cases in which the hindfoot is balanced and no equinus deformity has developed.
The hindfoot prosthesis requires more secure stabilization than a midfoot prosthesis to keep the heel from pistoning during gait. An anterior shell can be added to an ankle-foot prosthesis, or a posterior opening socket prosthesis can be used.
Partial calcanectomy, which consists of excising the posterior process of the calcaneus (Figure 11–12), should be considered an amputation of the back of the foot. In selected patients with large heel ulcerations or calcaneal osteomyelitis, partial calcanectomy can be a functional alternative to transtibial amputation. The removal of the entire posterior process of the calcaneus allows for fairly large soft-tissue defects to be closed primarily. Patients must have adequate vascular perfusion and nutritional competence for wound healing to occur. As with other amputations, partial calcanectomy creates a functional and cosmetic deformity. Use of an ankle-foot prosthesis with a cushion heel is usually required to replace the missing heel and prevent further skin ulceration.
In the Syme amputation, the surgeon removes the calcaneus and talus while carefully dissecting on bone to preserve the heel skin and fat pad to cover the distal tibia (Figure 11–13). The surgeon must also remove and contour the malleoli, but whether this should be done during the initial operation or 6–8 weeks later remains controversial. Proponents of the two-stage procedure argue that it can improve healing in patients with vascular disease. Opponents point out that it delays rehabilitation because the patient cannot bear weight until after the second stage of the operation. One series supports the use of the one-stage procedure, even in the presence of vascular disease or diabetes. A late complication of the Syme amputation is the posterior and medial migration of the fat pad. One of these surgical procedures can be done to stabilize the fat pad: tenodesis of the Achilles tendon to the posterior margin of the tibia through drill holes; transfer of the anterior tibial and extensor digitorum tendons to the anterior aspect of the fat pad; or removal of the cartilage and subchondral bone to allow scarring of the fat pad to bone, with or without pin fixation. Careful postoperative casting can also help keep the fat pad centered under the tibia during healing. The Syme amputation is one of the most difficult amputations to perform in terms of surgical technique and achievement of primary healing and heel pad stability.
Syme amputation with tenodesis of the Achilles tendon to the distal tibia.
Syme amputation should be designed to allow end bearing. Retaining the smooth, broad surface of the distal tibia and the heel pad allows direct transfer of weight from the end of the residual limb to the prosthesis. A transtibial or transfemoral amputation does not allow this direct transfer of weight. Because of the ability to end-bear, the amputee can occasionally ambulate without a prosthesis in emergency situations or for bathroom activities.
The Syme prosthesis is wider at the ankle level than is a transtibial prosthesis, and this cosmetic problem can be bothersome to some patients. The surgical narrowing of the malleolar flare and the use of new materials in the prosthesis, however, can improve the appearance of the final prosthesis. Moreover, patients can now benefit from energy-storing technology provided by the newly designed lower profile elastic response feet. Sockets do not need the high contour of a patellar-tendon bearing design because of the end-bearing quality of the residual limb. The socket can be windowed either posteriorly or medially if the limb is bulbous, or a flexible socket within a rigid frame design can be used if the limb is less bulbous. Because of the tibial flare, the socket used following Syme amputation is usually self-suspending.
Transtibial amputation is the most commonly performed major limb amputation. The long posterior flap technique (Figure 11–14) is now standard, and good results can be expected even in the majority of patients with vascular disease. Anterior and posterior flaps, sagittal flaps, and skewed flaps can be helpful in specific patients.
Transtibial amputation with long posterior flap technique.
Efforts should be made to preserve as much bone length as possible between the tibial tubercle and the junction of the middle and distal thirds of the tibia, based on the available healthy soft tissues. Amputations in the distal third of the tibia should be avoided because they result in poor soft-tissue padding and are more difficult to fit comfortably with a prosthesis. The goal is a cylindrically shaped residual limb with muscle stabilization, distal tibial padding, and a nontender and nonadherent scar (Figure 11–15). The transtibial amputation is especially well suited to rigid dressings and immediate postoperative prosthetic management. The removable rigid dressing has been shown to reduce hospital stay and time to initial fitting of a prosthesis. Distal tibiofibular synostosis (Ertl procedure) should be considered for the treatment of a wide trauma-induced diastasis to improve stabilization of the bone and soft tissue. The bone–bridge procedure recently was shown to have a higher complication rate, suggesting that its use be limited. The procedure is less often indicated in the treatment of patients with vascular disease. The synostosis is developed to create a broad bone mass terminally to improve the distal end-bearing property of the limb and minimize motion between the tibia and fibula. Although there is renewed interest in these techniques, true comparison of patients with osteomyoplastic techniques versus standard techniques has not been done.
Bilateral transtibial amputations that emphasize the benefits of the long posterior flap technique. The right limb, amputated by using equal anterior and posterior flaps, is conically shaped and atrophic. The left limb, amputated by using the long posterior flap technique, is cylindrical and well padded. (Reproduced, with permission, from Smith DG, Burgess EM, Zettl JH: Fitting and training the bilateral lower-limb amputee, in Bowker JH, Michael JW (eds): Atlas of Limb Prosthetics Surgical, Prosthetic, and Rehabilitation Principles. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2002; pp 599–622.)
A wide variety of prosthetic designs are available for the transtibial amputee. Sockets can be designed to incorporate a liner, which offers the advantages of increased comfort and accommodation of minor changes in residual limb volume. Disadvantages include increased perspiration and a less sanitary, less comfortable feeling in hot humid weather. Hard sockets are designed to have cotton or wool stump socks of an appropriate ply or thickness as the interface between the leg and the socket. Hard sockets are easier to clean and more durable than the liners are.
The Icelandic-Swedish-New York (ISNY) socket refers to the use of a more flexible socket material that is supported by a rigid frame. The flexible socket changes shape to accommodate underlying muscle contraction. This socket style can also be useful for limbs that are scarred or difficult to fit. Open-ended sockets with side joints and a thigh corset are not used much today except by patients who wore them successfully in the past and by patients with limited access to prosthetic care. The patellar tendon-bearing shape is most commonly used for the transtibial amputee. Despite its name, the majority of the weight is borne on the medial tibial flare and laterally on the interosseus space, whereas the rest of the weight is borne on the patellar tendon area. Even the new so-called total-contact transtibial socket, which is designed to have increased contact on all areas of the residual limb, preferentially loads the tibial flare and patellar tendon regions.
Numerous types of suspension devices are available for the transtibial prosthesis. The simplest and most common is a suprapatellar strap, which wraps above the femoral condyles and patella. Sockets can be designed to incorporate a supracondylar mold or wedge to grip above the femoral condyles, but this higher profile is bulkier and less cosmetic when the patient is sitting. A waist belt and fork strap are helpful for the patient who has a very short transtibial residual limb because these devices decrease pistoning in the socket; they are also helpful for the patient whose activities require extremely secure suspension. If the patient has a limb with poor soft tissue or has intrinsic knee pain, side hinges and a thigh corset can help unload the lower leg and transfer some of the weight to the thigh.
External suspension sleeves made of latex or neoprene are still used quite frequently. Latex is more cosmetic but less durable and can be constricting. Neoprene is more durable and not as constricting but sometimes causes contact dermatitis. The newest suspension uses an elastomeric or silicone-based liner that is rolled on over the residual leg and offers an intimate friction fit. A small metal post on the distal end of the liner then locks into a catch in the prosthetic socket to suspend the socket securely to the liner. Many patients who use these elastomeric locking liners like the secure suspension and feeling of improved control of the prosthesis. The liners have the disadvantages of being less durable and requiring frequent replacement. These elastomeric locking liners can be expensive. Although elastomeric locking liners were originally touted as preventing skin problems; rashes, skin irritation, and skin breakdown remain a frequent complaint even with this new technology, however. Approximately a third of amputees cannot tolerate the forces generated at the distal part of the amputation with liners using the metal post or pin lock system. New techniques were designed to attach the elastomeric liner to the socket with vacuum pumps, clips on the side of the liner, or sealing liners and one-way socket valves to maintain a suction between the liner and the socket. Suspension must be individualized, and no system is yet proven acceptable to all amputees.
Many different designs for prosthetic feet are now available, ranging from the original solid ankle cushion heel (SACH) foot to the newer elastic response technology with a variety of keel, ankle, and pylon designs. Cost and function can vary widely, and care should be used in prescribing an appropriate prosthetic foot for an individual patient. A common error is to prescribe a foot that is either too stiff or does not get to feel flat quickly enough for an individual patient, especially in the first 12–18 months after an amputation.
Disarticulation through the knee joint (Figure 11–16) is indicated in ambulatory patients when a below-knee amputation is not possible but suitable soft tissue is present for a knee disarticulation. These circumstances are most commonly found in cases involving traumatic injuries. In patients with vascular disease, the blood supply is such that if a knee disarticulation would heal, a short transtibial amputation would usually heal as well. The knee disarticulation is indicated in patients who have vascular problems and are nonambulatory, especially if knee flexion contractures or spasticity are present. Although sagittal flaps or the traditional long posterior flap can be used to take advantage of the best available soft-tissue coverage, newer literature supports use of the posterior flap technique when possible. The patella is retained and the patellar tendon sutured to the cruciate stumps to stabilize the quadriceps muscle complex. The biceps tendons can also be stabilized to the patellar tendon. A short section of gastrocnemius muscle can be sutured to the anterior capsule to pad the distal end. Although many techniques are described to trim the condyles of the femur, trimming is rarely necessary, and radical trimming can decrease some of the advantages of the knee disarticulation.
For ambulatory patients, the advantages of a knee disarticulation over a transfemoral amputation include improved socket suspension by contouring above the femoral condyles, the added strength of a longer lever arm, the retained muscle balance of the thigh, and most important, the end-bearing potential to transfer weight directly to the prosthesis. In the past, the objections to a bulky prosthesis and asymmetric knee-joint level led many surgeons to abandon the practice of performing knee disarticulations. New materials allow a less bulky prosthesis to be fabricated, and the four-bar linkage knee unit, which can fold under the socket, improves the appearance of the prosthesis when the patient is sitting. The four-bar linkage knee remains the prosthetic knee of choice for a knee disarticulation. It is low profile, has excellent stability, and can incorporate a hydraulic unit for control during the swing phase of gait in patients who can walk at different cadences.
For nonambulatory patients, a knee disarticulation eliminates the problem of knee flexion contractures, provides a balanced thigh to decrease hip contractures, and provides a long lever arm for good sitting support and transfers.
The Gritti-Stokes amputation is not recommended. In this operation, the patella is advanced distally and fused by arthrodesis to the distal femur, theoretically to allow direct weight bearing. The concept behind this operation is flawed because even in normal kneeling, the weight is borne on the pretibial and patellar tendon areas and not on the patella. The added length and the asymmetry of the knee joints complicate prosthetic fitting.
Transcondylar amputation can be performed, but the end-bearing comfort and improved suspension of a transcondylar amputation appear to be diminished when compared with the true knee disarticulation.
Transfemoral amputation is usually performed with equal anterior and posterior fish-mouth flaps. Atypical flaps can and should be used to save all possible femoral length in cases of trauma because the amount of function is directly proportional to the length of the residual limb. Residual limb wound problems resulting in delayed ambulation with immediate postoperative prostheses should be treated, rather than revised, when possible to preserve length. One means proposed for this is the incorporation of the vacuum-assisted closure system into the fitting process. Rehabilitation is not delayed while wound healing occurs.
Muscle stabilization is more important in the transfemoral amputation than in any other major limb amputation. The major deforming force is into abduction and flexion. Myodesis of the adductor muscles through drill holes in the femur can counteract the abductors, prevent a difficult adductor tissue roll in the groin, and improve prosthetic control (Figure 11–17). Without muscle stabilization, the femur commonly migrates laterally through the soft-tissue envelope to a subcutaneous location. Newer transfemoral socket designs attempt to better control the position of the femur, but they are not as effective as muscle stabilization. Even in nonambulatory patients, muscle stabilization is helpful in creating a more durable, padded residual limb by preventing migration of the femur.
Transfemoral amputation with adductor myodesis.
An IPOP and rigid dressings are more difficult to apply and keep positioned after a transfemoral amputation than after more distal amputations. IPOP techniques do offer the advantages of early rehabilitation and control of edema and pain, and these techniques are preferred if the expertise to use them is available. The major complaints of patients with the transfemoral IPOP are the weight of the cast and the discomfort when sitting. In many cases, only a soft compressive dressing alone is used, and in these patients, the dressing should be carried proximally around the waist as a spica to better suspend the dressing and to include the medial thigh and prevent the development of an adductor roll of tissue. Proper postoperative positioning and therapy are essential to prevent hip flexion contractures. The limb should be positioned flat on the bed, rather than elevated on a pillow, and hip extension exercises and prone positioning should be started early.
Suspension of the prosthesis is more complicated in transfemoral amputations than in more distal amputations because of the short residual limb, the lack of bony contours, and the increased weight of the prosthesis. The transfemoral amputation prosthesis can be suspended by suction, Silesian bandage, hip-joint and pelvic band, or the newer elastomeric locking liners.
Traditional socket-suction suspension works when the skin forms an airtight seal against the socket. Air is forced distally through a small one-way valve when the prosthesis is donned and with each step during gait, thus maintaining negative pressure distally in the socket. No prosthetic sock or other liner is used between the hard socket and the limb because air leaks out around the sock and prevents suction from developing. Donning a socket-suction prosthesis requires skill and exertion, and patients must have good coordination, upper extremity function, and balance to perform this task. Socket-suction systems work well for average-to-long transfemoral residual limbs that have adequate soft tissues and stable shape and volume. It is usually comfortable and the most cosmetically acceptable method of socket suspension.
A Silesian bandage is a flexible strap that attaches laterally to the prosthesis, wraps back around the waist and over the contralateral iliac crest, and then comes forward to attach to the anterior proximal socket (Figure 11–18). It provides good suspension and added rotational control of the prosthesis. A Silesian bandage is commonly used to augment suction suspension for patients who have shorter-length limbs or for patients whose activities require more secure suspension than suction alone can offer.
Silesian band suspension of a transfemoral prosthesis.
As with the transtibial prosthesis, the newer elastomeric locking liners can provide excellent suspension and control. An elastomeric or silicone-based liner is rolled onto the leg similar to the way a condom is applied. This liner has an intimate fit with the residual limb and avoids pistoning and rotational forces. A small metal post at the distal end of the liner locks down into a catch at the bottom of the prosthetic socket to create a secure mechanical suspension. A small button must be pushed to disengage the lock and release the prosthesis. Many amputees express an improved sense of security and improved proprioception with these systems. The disadvantages continue to be the added cost, the need to replace the liners as they tear, and rarely, developing a contact dermatitis. As discussed with transtibial amputees, approximately a third of amputees cannot tolerate the forces generated at the distal part of the amputation with liners using the metal post or pin lock system. For these patients, new methods to attach the liner to the socket must be explored.
The hip joint and pelvic band provides extremely secure suspension and control, but the band is bulky, the least cosmetically acceptable method of suspension, and the least comfortable, especially when the patient is sitting. The pelvic band, made of metal or plastic, is thicker than a Silesian bandage. The pelvic band runs from the hip hinge, around the waist, between the contralateral iliac crest and trochanter, and back to the hip hinge. The hinge is located laterally, just anterior to the trochanter, over the anatomic axis of the hip joint. Hip joint and pelvic band suspension is indicated for very short transfemoral limbs, geriatric patients who cannot don a suction suspension, and obese patients who cannot get adequate control with suction, silicone suspension sleeves, or Silesian band suspension.
Socket design for the transfemoral amputation has changed. The traditional quadrilateral socket has a narrow anteroposterior diameter to keep the ischium positioned back and up on top of the posterior brim of the socket for weight bearing. The anterior wall of the socket is 5–7 cm higher than the posterior wall to hold the leg back on the ischial seat. Anterior pain is a frequent complaint and should be addressed by modification of the prosthetic socket in a small local area such as over the anterior superior iliac spine. If the entire anterior wall is lowered or relieved, the ischium slips inside the socket and totally alters the load transfer and pressure areas. Even though the lateral wall is contoured to hold the femur in adduction, the overall dimensions of the quadrilateral socket are not anatomic and provide poor femoral stability in the coronal plane.
Narrow mediolateral transfemoral socket designs attempt to solve the problems of a traditional quadrilateral socket by contouring the posterior wall to set the ischium down inside the socket, not up on the brim. Weight is transferred through the gluteal muscle mass and lateral thigh instead of the ischium, which eliminates the need for anterior pressure from a high anterior wall. Attention is then focused on a narrow mediolateral contour to better hold the femur in adduction and minimize the relative motion between the limb and the socket. The normal shape and normal alignment (NSNA) socket and the contoured adducted trochanteric-controlled alignment method (CAT-CAM) socket are two of the narrow mediolateral designs available.
A socket made of flexible material with a rigid frame can also be used. The flexible material allows socket wall expansion with underlying muscle contraction. A flexible socket can be made in either the traditional quadrilateral or narrow mediolateral shapes. Advantages of this type of socket include improved comfort in walking and sitting and possibly improved muscular efficiency. One drawback is that the flexible material is less durable, and cracks can result in the loss of suction suspension and skin irritation.
Prosthetic knee joints are available in many designs to address specific patient needs. The traditional standard was the single-axis constant-friction knee. The constant-friction knee is simple, durable, lightweight, and inexpensive. The friction can be set at only one level to optimize function at one cadence, and patients have difficulty when walking at different speeds.
Outside hinges were the old standard for the knee disarticulation patient, to better approximate the center of motion of the knee. Outside hinges are cosmetically poor but still available for patients who used them successfully in the past and remain satisfied with them. For new patients, other types of knee units are used.
The term stance control knee has replaced the term safety knee. It refers to a knee unit that has weight-activated friction to increase stability and resistance to buckling as more of the amputee's body weight is applied. This unit is particularly useful for patients who are older, feel less secure, and have a very short residual limb, weak hip extensors, or hip flexion contractures.
A polycentric knee provides a changing center of rotation that is located more posteriorly than other knee joints. The posterior center of rotation offers more stability during stance and the first few degrees of flexion than other knee units do. The four-bar knee is one of many polycentric knee units available.
A hydraulic or pneumatic unit can be added to most knee joints to provide superior control of the prosthesis in swing phase by using fluid hydraulics to vary the resistance according to the speed of gait. This option is useful in active amputees who walk and run at different speeds. The variable-friction knee unit can be a less expensive way to accommodate patients who walk at different speeds. This knee changes the friction according to the degree of flexion in the knee unit and leads to an improvement in the swing phase of walking. Although a variable-friction knee is less costly and requires less maintenance than a hydraulic unit, it is not as effective in allowing the amputee to walk at different cadences.
A manual locking option can also be added to most knee units to lock the knee in full extension. Locking is helpful if the patient is blind, feels less secure, has a very short residual limb, or is a bilateral amputee.
As mentioned previously, microprocessor-controlled so-called intelligent knee units incorporate the latest technology to provide superior control of the swing and stance characteristics or the knee and respond to the amputee's speed, cadence, and accelerations. Recent studies show these knee units can improve function and assist amputees to increase their Medicare Functional Classification Level from 2 to 3 (Table 11–1). Technology has not yet advanced enough for knee units to replace the tremendous motor power lost when an amputation is done above the knee.
Table 11–1. Medicare Functional Classification Level (MFCL) Descriptions. ||Download (.pdf)
Table 11–1. Medicare Functional Classification Level (MFCL) Descriptions.
Does not have the ability or potential to ambulate or transfer safely with or without assistance and a prosthesis does not enhance quality of life or mobility.
Has the ability or potential to use a prosthesis for transfers or ambulation on level surfaces at fixed cadence. Typical of the limited and unlimited household ambulator.
Has the ability or potential for ambulation with the ability to traverse low-level environmental barriers such as curbs, stairs, or uneven surfaces. Typical of the limited community ambulator.
Has the ability or potential for ambulation with variable cadence. Typical of the community ambulatory who has the ability to traverse most environmental barriers and may have vocational, therapeutic, or exercise activity that demands prosthetic utilization beyond simple locomotion.
Has the ability or potential for prosthetic ambulation that exceeds the basic ambulation skills, exhibiting high impact, stress, or energy levels, typical of the prosthetic demands of the child, active adult, or athlete.
Specifically designed prostheses known as stubbies are initially recommended for bilateral knee disarticulation or transfemoral amputees, regardless of age, who have lost both legs simultaneously but are candidates for ambulation. Stubbies consist of prosthetic sockets mounted directly over rocker-bottom platforms that serve as feet. The rocker-bottom platforms have a long posterior extension to prevent the patient from falling backward, and they have a shortened anterior process that allows smooth rollover into the push-off phase of gait. These prostheses look as if the foot were positioned backward. The use of stubbies results in a lowering of the center of gravity, and the rocker bottom provides a broad base of support that teaches trunk balance, provides stability, and allows the patient to build confidence during standing and ambulation. As the patient's confidence and skills improve, periodic lengthening of the stubbies is permitted until the height becomes nearly compatible with full-length prostheses, at which time the transition is attempted. Many patients reject full-length prostheses and prefer the stability and balance afforded by the stubbies.
Hip disarticulation (Figure 11–19) is rarely performed. Surgically, the traditional racket-shaped incision with an anterior apex is used in patients with vascular problems and in trauma-injured patients when possible. In tumor surgery, creative flaps based on the uninvolved anatomic compartments must be designed.
Prosthetic replacement can be successful in healthy young patients who required hip disarticulation because of trauma or cancer but is generally not indicated for patients with vascular disease. The standard prosthesis is the Canadian hip disarticulation prosthesis. The socket contains the involved hemipelvis and suspends over the iliac crests. Although the hip joint and other endoskeletal components are made of lightweight materials in an effort to keep the weight to a minimum, the prosthesis is still heavy and difficult to manipulate. Ambulation with the prosthesis usually requires more energy than it would take to ambulate with crutches and a swing-through gait. For this reason, many ambulatory patients use crutches and no prosthesis. The advantage of the prosthesis is that it does allow freer use of the upper extremities.
Although a hemipelvectomy (Figure 11–20) is even less frequently required than a hip disarticulation, it is sometimes indicated for trauma injuries or cancer involving the pelvis. Use of a prosthesis after this procedure is extremely rare because the body weight must be transferred onto the sacrum and thorax. Special considerations for seating are usually required after hemipelvectomy.
Prosthetic Prescription Following Amputation at or Above the Knee
To be considered a candidate for a high anatomic level prosthesis (knee disarticulation and higher), a patient must be able to transfer independently, rise from sitting to standing independently, and ambulate using one leg and a swing-through gait over a distance of 100 feet on the parallel bars or with a walker. Although these requirements seem extreme, they are necessary for the successful use of this heavy and complicated prosthesis. The use of a transtibial prosthesis can make it easier to transfer and to ambulate. But a current transfemoral prosthesis can make it much more difficult to rise from sitting to standing because the powerful motor force required to extend the knee is not present. High-level prosthetic devices can actually increase the energy required for walking compared with one-leg swing-through gait. Unfortunately, without the ability to meet the activity demands unassisted, a prosthesis acts as an anchor to decrease overall independence. We use these same activity requirements as a functional test before prescribing a prosthesis for all transfemoral, hip disarticulation, and hemipelvectomy amputees.
Percutaneous Direct Skeletal Attachment of Artificial Limbs
The benefits of attaching prosthetic limbs through the skin, directly to the skeleton, were envisioned for nearly 100 years. Documentation of temporary external fixation for fractures dates to Malgaigne in 1845. During and just after World War II, independent attempts were made in Germany and the United States to attach a transtibial prosthesis directly to the tibia. Four humans were fit in May 1946 by Drummer, a general surgeon in Pinneberg, Germany. The two major hurdles continue to be the bone–implant interface, and the skin–implant interface. Breakthrough work by Branemark in Gothenburg, Sweden, advanced the use of titanium and improved design implants that led to over 30 years of successful dental and maxillofacial reconstruction with prosthetic devices directly connected to the bone of the mouth and face.
The skin of the extremities posed a larger challenge to the cutaneous–implant interface. Improvements in implant design and surgical technique, however, made it possible to implant and fit thumb, forearm, and transfemoral amputees successfully. Approximately 60 amputees have undergone surgical implantation and prosthetic fitting in Sweden, the United Kingdom, and Australia.
The early results confirm the potential promise of major improvements in attachment, proprioception, and function of osseointegrated prosthetic limbs compared with socket-style prostheses. Much work remains to be accomplished, however, especially in the skin–implant interface. A tremendous improvement in the bone–implant interface led to results that far outdistance historical attempts at directly attaching artificial limbs to the skeleton. Without true cutaneous–implant integration that provides a durable and biologic barrier, however, the risk of bacterial migration causing infection and loosening continues. It is fantastic to see this dream continue and advance.
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