137: Chest Wall Stabilization and Novel Closures of the Chest

Prior to the 1950s, the approach to treating skeletal trauma or deformity of the chest was largely nonoperative. Advances in anesthesia, cardiothoracic surgery, bioprosthetic materials, and mechanical ventilation in the second half of the 20th century reduced the morbidity and mortality of operating in the chest, creating a safer environment for surgical intervention. Potential indications for rib fracture repair include flail chest, non-united rib fractures refractory to conventional pain management, chest wall deformity or defect, and trauma-associated rib fracture and respiratory failure which may be repaired during thoracotomy for other traumatic injury. Several effective repair systems have been developed. These have made plating of ribs and stabilization of the chest wall safe, effective, and easy to perform. Future directions for progress on this important surgical problem include the development of minimally invasive techniques and the conduct of multicenter, randomized trials. In this chapter, we propose a unique classification for flail chest based on vector force applied to the chest wall and its underlying physiologic response to that force.

Flail chest has been alternately described as “stoved-in” or “crushed” chest. Nonoperative approaches have included external strapping, placement of sandbags, or positioning of the patient with the injured side down. These methods have been used with relative success to stabilize unilateral flail chest, but for complex injuries, such as bilateral flail chest, mediastinal flail, and large chest wall soft tissue defects, a different strategy is clearly required. External fixation combined with traction was eventually described and largely used during the initial phase of management of flail chest. The prolonged bed rest necessary for fracture union, however, led surgeons to consider internal fixation. Intramedullary “rush nail” fixation was first reported in 1956.¹ Another major factor was the introduction of positive pressure mechanical ventilation. Its adoption and success in preventing respiratory failure in patients with multiple rib fractures and flail chest rendered external fixation/traction obsolete.

By the 1960s and 1970s surgeons recognized that select patients with flail chest might benefit from surgical fixation even after brief periods of mechanical ventilation had failed. Sporadic series attempting rib fracture repair using a number of techniques, including plating, wiring, and intramedullary rods, were reported.^2–9 Brunner was the first to successfully repair a case of sternal flail using a substernal stainless steel prosthesis, the same technique used to reconstruct pectus excavatum.¹⁰

The indications for surgery in flail chest and rib fracture repair are summarized in Table 137-1. Both acute and chronic problems are amenable to surgery.

Flail chest is a complex injury involving multiple rib fractures that cause a segment of the thoracic cage to separate from and move independently of the remaining chest wall. To be classified as flail chest, the segment must involve at least two consecutive ribs, and each rib must have a minimum of two fractures. Large fail segments involve more than two ribs, a greater proportion of the chest wall, and often extend bilaterally or involve the sternum (Fig. 137-1). Flagel et al. found that age greater than 45 years and presence of six or more rib fractures are associated with a worse prognosis and higher complication rate. They further reported that the larger the force applied to the chest wall, lungs, and intrathoracic organs, the greater the severity of pain and physiologic derangement.¹¹

Clinically, flail chest is diagnosed when an unstable segment of the rib cage causes paradoxical motion of the chest wall visible on respiration (Fig. 137-2 A,B). Sternal flail occurs when the sternum becomes dissociated from the hemithoraces as a result of either unilateral or bilateral rib fractures associated with costochondral dissociation. These anatomical and mechanical changes will eventually lead to respiratory fatigue, inadequate ventilation, atelectasis, ventilation/perfusion mismatch (shunt), hypoxemia, and pulmonary failure (Fig. 137-3). Two randomized trials have been conducted supporting the notion that selected patients with flail chest may experience short- and long-term benefits from operative repair. The surgically repaired groups in both trials demonstrated significantly fewer days on the ventilator and in the ICU, and had a lower incidence of hospital-acquired pneumonia, better pulmonary function at 1 month follow-up, and a higher rate of return to work at 6 months compared with the nonoperative groups. Visual chest wall deformity or persistent flail chest occurred less frequently in the operative groups, whereas forced vital capacity and total lung capacity were significantly higher in the operative groups at 2 months.^12,13

Recent, nonrandomized, cohort comparison trials have generally confirmed these findings with the caveat that flail chest repair is usually not advised in patients with significant pulmonary contusions.^14–16 The optimal number of days after injury to perform repair is controversial: one trial randomized patients at 5 days¹² and the other at 36 to 48 hours.¹³ In our experience, the repair can be safely performed up to 15 days after injury, before a healing callus begins to form around the fractures, as after this point the callus must be removed to achieve complete alignment of the rib fragments and bony union.

On the basis of our 10-year clinical experience, we developed a new classification for flail chest (Table 137-2), using the vector of the force (blow) applied to the chest (Fig. 137-4) as a guide to determining the optimal approach for treatment of complex chest wall injuries.¹⁷ The chest wall is similar to a ring. When sufficient force is applied to one side of the ring, the energy associated with the force is transmitted to the opposite side. Depending on the magnitude of the force, the structures contained within the chest, such as the lung, heart, and mediastinal structures, may cause the ring to break at two points. Most patients presenting with flail chest have unilateral flail segments with minimal respiratory derangement. These injuries are classified as type I. The majority of these patients can be treated with pain management, respiratory therapy, and early ambulation. Patients with type II injuries require repair of at least one side of the chest, since the intrathoracic structures will have absorbed some of the force transmitted to the opposite side. The exception is the patient who sustains a lateral blow followed by a “counter coup” injury. Patients presenting with type III, IV, and V flail chest have sustained substantial trauma to their chest, and most likely require immediate surgical repair. Figure 137-5 offers a simplified guideline for the management of rib fracture and flail chest.

Chest wall defects/deformities occur in a variety of traumatic circumstances and are characterized by severely displaced rib fractures that visibly deform the chest wall with or without soft tissue loss. Paradoxical motion may not be present in many of these patients, especially in patients with adequate pulmonary reserve. Minimal to moderate-sized tissue defects (<10 × 10 cm) can be caused by penetrating missiles or impalement by surrounding objects during a motor vehicle crash (MVC) or fall. Repair of both rib fractures and soft tissue may be indicated to restore an incompetent or “caved in” segment of the chest wall. Nonoperative management will eventually lead to the development of chest wall herniation. Larger chest wall defects, such as those resulting from close-range shotgun blasts or explosions should be repaired by a multidisciplinary team, including plastic, orthopedic, and neurosurgeons. Diaphragmatic transposition, involving detachment of the diaphragm peripherally and suture above the chest wall defect, has been described for lower chest wall defects.¹⁸ This procedure converts the chest wall injury to an abdominal wall defect and provides soft tissue support for the rib cage.

Acute Pain and Disability Reduction

The majority of rib fractures heal without complications and long-term disability. However, patients may present several months after traumatic injury with displaced and movable rib fractures. These patients do not require assisted ventilation, such as BiPAP, but do experience persistent, unrelenting pain with respiration, coughing, or mobilization. Such patients may benefit from having their fractures surgically stabilized. One should exercise clinical judgment, however, and disclose the risks of long-term pain and disability that may persist despite a successful surgical repair.

Nonunion

A small percentage of rib fractures do not heal, presumably because the angulation and displacement of the fracture is too severe. Although a fibrous capsule may envelope the fracture, bony union has not occurred. A chronic nonunion may cause intermittent discomfort associated with movement of the fracture and can be quite disabling for the patient. The rationale for nonunion repair is based on the assumption that without intervention, complete bony healing will not occur. It is of paramount importance that the fibrous callous enveloping the nonunion be resected and a plate placed to fixate the rib ends.

Thoracotomy for Other Indications

A patient with multiple rib fractures or flail chest who needs a thoracotomy for another indication, for example, open pneumothorax, pulmonary laceration, retained hemothorax, or diaphragm laceration, is a candidate for rib fracture repair provided it does not increase the morbidity of the original operation. Otherwise the repair should be delayed and undertaken when the patient is stable. Thoracotomy for nontraumatic indications, for example, tumor resection, also may result in rib fractures that may need to be surgically repaired.

Technical Considerations of Rib Fracture Repair

The goals of rib fracture repair are to target unstable fractures and flail chest segments, improve respiratory function, promote early separation from mechanical ventilator support, ensure early ambulation, decrease the need for prolonged pain medication, decrease recovery time, and accelerate the patient's return to work. The chest anatomy is unique owing to the tight association between the mechanical properties of the chest wall, muscles, and ribs with the underlying lung parenchyma, heart, and mediastinal structures (Fig. 137-6). The human rib thickness ranges from 8 to 12 mm and has a relatively thin (1–2 mm) cortex that surrounds the soft marrow. Individual ribs do not have an abundance of stress tolerance, and the rib with its thin cortex does not hold a cortical screw as well as bone, which has a thicker cortex. Rib fractures may be comminuted, oblique, displaced, or fragmented in several areas along the same rib, further increasing the challenge for a reliable repair. In addition, the intercostal nerve lies along the undersurface of the rib. Intercostal nerve injury during operation or crimping may lead to post-thoracotomy pain syndrome.

Many techniques have been described for repairing rib fractures and flail chest, that is, wire suturing of ribs, intramedullary wires, fixation with various types of plates made of metal or absorbable materials. Anterior plating with bicortical locking screws and intramedullary rods has become the standard of care for these injuries and is a time-tested technique against which innovations should be compared (Fig. 137-7).

The Judet strut is a bendable metal plate that grasps the rib with tongs both superiorly and inferiorly without transfixing screws.⁴ The fixation of this plate around the inferior margin of the rib usually crimps the intercostal neurovascular bundle. It therefore has the potential to cause intercostal nerve injury and chronic pain. Absorbable plates are polylactide polymers that have been successfully used to fixate maxillofacial, tibial, and rib fractures. Polylactide and polydioxanone prostheses also have been successfully used for the reconstruction of chest wall deformities and for rib reapproximation after thoracotomy for nontraumatic indications.^19,20 Absorbable plates have practical and theoretical advantages over titanium plates, that is, they do not need to be removed and because metal plates are made of titanium, “stress-shielding” of the plated bone is possible. “Stress-shielding” occurs because the plated bone is protected from normal stress and therefore does not heal as robustly as nonplated bone. A few animal models support the concept that fractures heal faster and stronger with absorbable plates compared with metal.^21,22 However, polylactide plates are not bacteriostatic and they may still get infected in vivo.

Preoperative Preparation

The majority of the patients who require surgical repair of rib fractures and flail chest are classified as type III or greater. These patients usually have injuries involving more than one system, such as head trauma, multiple skeletal fractures (spine, pelvis, long bones), abdominal injuries, and lung contusion on positive mechanical ventilation in the ICU. It is important to segregate the degree of respiratory compromise due to flail chest from the degree of compromise caused by the underlying pulmonary contusion and competing injuries. One should be careful not to offer treatment when the degree of physiologic derangement is such that the patient may not be able to tolerate either single lung ventilation or a prolonged surgical procedure. On the other hand, there are a few cases for which performing emergency thoracotomy, lung resection, and rib stabilization is indicated (Figs. 137-8 to 137-11A,B). Three-dimensional CT reconstructions may be useful to completely define all rib fractures and the extent of their displacement and to help plan the surgical approach (Fig. 137-8). A preoperative antibiotic to target gram-positive organisms is given 30 minutes before incision. Video-assisted thoracoscopic surgery (VATS) may be used for pulmonary resections, evacuation of hemothorax, diaphragmatic repair, and to aid in localizing the flail segment from pushing on the skin surface and observing the exact segment to be repaired. This maneuver can be especially helpful in patients with generous subcutaneous and/or breast tissue.

Among 650 rib fracture repairs described since 1975, there were eight superficial wound infections (1.2%), four cases of wound drainage without infection (0.6%), two pleural empyemas (0.3%), one wound hematoma, and one persistent pleural effusion.^{5–7,11–16,23–41} Fixation failure, including plate loosening or wire migration, occurred in eight patients (1.2%), and postoperative chest wall “stiffness,” “rigidity,” or “pain” necessitating plate removal was reported in nine patients (1.4%). Rib osteomyelitis was reported in one patient and was ascribed to operative contamination from a preoperative chest tube, which was colonized by Staphylococcus aureus.

Minimally Invasive Approaches

The advent of three-dimensional reconstruction of chest CT scanning has had a positive impact on the diagnosis and planning of rib fracture repair and flail chest. The addition of intraoperative VATS may improve the surgeon's ability to keep the external exposure to a minimum. Muscle-sparing techniques, along with new instruments and plating systems, permit easy repair. In addition, because we do not recommend plating every segment of the flail chest, since the goal is to promote chest wall stabilization and improve the respiratory mechanics, thoracotomy can sometimes be avoided in favor of minimally invasive approaches. These strategies for minimizing operative dissection should reduce the postoperative morbidity. As well, new technologies and plating systems have been designed exclusively for thoracoscopic repair.