Post-traumatic rib cage and chest wall hernias

INTRODUCTION — Post-traumatic rib cage hernias and chest wall defects are rare but serious injuries with a high risk of mortality and chronic disability. The most commonly herniated viscera are the lung, liver, and colon. Surgical management, indicated in most patients, is challenging but can mitigate disability and allow the patient to return to their preinjury status. Low-grade injuries require only careful reduction and soft tissue closure, but higher-grade injuries usually need surgical rib fixation with prosthetic and/or tissue flap coverage.

This topic will review the epidemiology, presentation, initial management, and treatment options of traumatic rib cage hernias and chest wall defects in children and adults. The fundamentals of initial trauma management and thoracic trauma, including rib fractures, are discussed separately:

●(See "Initial management of trauma in adults".)

●(See "Initial evaluation and management of rib fractures".)

●(See "Initial evaluation and management of chest wall trauma in adults".)

●(See "Initial evaluation and management of blunt thoracic trauma in adults".)

●(See "Initial evaluation and management of penetrating thoracic trauma in adults".)

●(See "Thoracic trauma in children: Initial stabilization and evaluation".)

●(See "Chest wall injuries after blunt trauma in children".)

ETIOLOGIES, PATHOGENESIS, AND EPIDEMIOLOGY

Adult — The etiology of the vast majority of rib cage hernias is post-traumatic, but there are many other known causes: iatrogenic (eg, postoperative), spontaneous (eg, after coughing), infectious, congenital, and neoplastic [1-3]. In the past, the injury was predominantly penetrating (eg, bullet, sword/knife/bayonet, and shrapnel wounds) [4]. By contrast, blunt injury mechanisms are more common today [5]. Modern etiologies include motor vehicle crashes (50 percent), falls (21 percent), gunshot wounds (17 percent), animal attacks (8 percent), and blast injuries (4 percent). Victims are most frequently male.

Rib cage hernias exhibit a loss of musculoskeletal continuity and commonly contain both bony and soft tissue deficiencies. Herniation may also result from disruption of only musculature with the bony structures intact. The injury may be a simple laceration (eg, a stab wound) or may be destructive with a well-defined defect. High-energy blunt or high-velocity/destructive penetrating mechanisms are generally required, but low-energy blunt mechanisms are also seen [5-8].

Spontaneous rib cage hernias typically result from severe or prolonged coughing [9,10]. With chronic repetitive stress (eg, breathing and exertion), injured muscle attenuates, and unhealed rib fractures or rib loss compound the risk. In delayed presentations, the lung may have migrated into the subcutaneous space.

For all etiologies, however, the incidence is exceptionally low, amounting to case reports and abbreviated case series only [3,11].

Pediatric — Cases of post-traumatic rib cage hernias have also been reported in children and adolescents. In this population, the most common causal mechanism is a bicycle crash with handlebar injury to the chest wall [12,13]. Other causes include fall from height, fall onto object, object fall onto child, cow kick, and tricycle crash [13]. Because of the pliability of immature bone, an intercostal muscle tear leading to a hernia in a child may not have a detectable rib fracture [12,13].

PRESENTATIONS — Rib cage hernias occur immediately or within weeks, months, or years after injury [1,3-5].

Acute — Patients with acute hernias present with respiratory symptoms ranging from dyspnea to hypoxic respiratory failure. The majority of symptoms result from lung injury (pulmonary contusion), lung entrapment, or rib fractures. Patients may manifest additional nonthoracic blunt injuries or penetrating injuries to the heart, lungs, great vessels, spine, or upper abdominal organs. (See "Initial evaluation and management of blunt thoracic trauma in adults" and "Initial evaluation and management of penetrating thoracic trauma in adults" and "Thoracic trauma in children: Initial stabilization and evaluation".)

Chronic — Chronic rib cage hernias often have minimal symptoms or may be asymptomatic [1,3,14,15]. Patients may first notice pain, and some patients will report a bulge that appears with forced inhalation/exhalation, Valsalva, or coughing (movie 1). If a hernia is present on examination, it will be soft and crepitant, and lung sounds may be auscultated. If the hernia is located at the costochondral border, bowel sounds suggest the colon is herniated. If the hernia is reducible, it will readily reappear with Valsalva or coughing.

DIAGNOSIS — Rib cage hernia can be diagnosed clinically or radiographically. Full-thickness chest wall defects with or without tissue loss and lung herniation into the subcutaneous tissues or evisceration through a wound are rare [5]. If not apparent on physical examination, subcutaneous herniation can be confirmed by imaging. On plain chest radiograph, a hazy opacity adjacent to the chest wall will be seen. Computed tomographic (CT) axial imaging will demonstrate herniated lung and/or abdominal viscera.

MANAGEMENT

Initial management — A patient with an open chest wall defect or herniation will need a moist, semiocclusive dressing to protect the pleural space and lung from further contamination [16]. Prophylactic intravenous antibiotics are recommended for open chest wounds.

Since associated injuries will be common with blunt or penetrating torso trauma, the patient should be evaluated, resuscitated from shock, and imaged in the same manner as other severely injured patients. (See "Initial evaluation and management of blunt thoracic trauma in adults" and "Initial evaluation and management of penetrating thoracic trauma in adults" and "Thoracic trauma in children: Initial stabilization and evaluation".)

Depending on severity of injury, obtaining airway and supportive ventilation and/or damage control surgery of the chest and/or abdomen may be necessary [17]. (See "Overview of damage control surgery and resuscitation in patients sustaining severe injury".)

Definitive management — Rib cage hernias are managed nonoperatively or operatively depending on etiology, anatomic position, and symptomatology [5,11].

Nonoperative management — If there are no associated injuries, minimal or no lung herniation, low risk of strangulation, and lack of symptoms, a highly select group of patients can be observed and managed with continuous chest strapping/bandaging and followed up with short-interval repeat imaging to assess for closure of the defect [7,18,19]. Successful nonoperative management has been more commonly reported in children [13]. (See 'Pediatric rib cage hernias' below.)

Operative management — The majority of acute traumatic rib cage hernias in adults, especially those with tissue loss, should be operatively repaired. Traumatic rib cage hernias are often complex injuries. As such, the operative approach needs to be well planned for each component of the injury, including initial hernia reduction; assessment and repair of the soft tissue and hernia defects; and stabilization of the bony thorax, which often entails rib-plating techniques, followed by coverage of the defect and hernia repair [5].

Timing of surgical repair — Acute injuries with tissue loss or visceral exposure/incarceration, with or without contamination, should be operated immediately with the caveat that damage-control techniques may precede a definitive repair delayed by one to two days. Closed acute hernias without incarceration for which repair is indicated should be operated within one to several days, depending on other injuries and patient condition. Semi-acute or chronic herniations may be repaired electively.

Exposure — The patient is positioned to expose the injury plus as much of the surrounding chest wall as feasible. Most commonly, the patient will be in a lateral decubitus position, although anterior defects are approached supine and posterior defects prone. Single-lung ventilation may be helpful. Although historically chest wall hernias have been repaired through incisional exposure, reports of minimally invasive approaches are now common [15,20].

Hernia reduction — Induction of general anesthesia will relax the musculature of the chest wall and may cause the hernia to spontaneously reduce [21]. When the hernia and/or hernia sac does not reduce, the adherent hernia sac should be dissected from the surrounding tissue and the lung assessed for viability. Viable lung can be manually reduced. If the herniated lung is viable but unable to be manually reduced, then additional division of the intercostal muscles and pleura on each side of the defect will allow for reduction.

In injuries created by high-energy or crushing mechanisms, the full extent of tissue damage may not be apparent at the first operation. Clearly nonviable or severely injured lung, intercostal muscle, and devascularized rib should be resected (picture 1). Damage control temporary chest wall closure with a chest tube and a vacuum dressing and reoperation in 24 to 48 hours may be prudent [16,17].

Hernia repair — The approach to the hernia defect depends on the size of the defect, the viability of the surrounding soft tissue, and the presence and severity of any associated rib fractures [2,3,5,14]. A grading system has been proposed that categorizes chest wall injuries on a scale of 1 to 5, ranging from least to most severe [5].

●For low-grade injuries (grade 1 to 2), a primary tissue repair can usually be performed with a layered suture closure of the surrounding muscle and soft tissue. Rib fractures may require reapproximation with wire sutures (grade 1) or plating (grade 2 and higher). As most hernias are within the intercostal space, the time-honored option of creating periosteal flaps above and below the defect is recommended in select cases [1,9,22]. The periosteal flap of the superior rib is reflected over the defect, and the periosteal flap of the inferior rib is reflected superiorly. The periosteal flaps are sutured together over the defect, and the overlying soft tissues are reapproximated.

●When the defect cannot be primarily closed (grade 3 and higher), prosthetics and/or flap coverage options should be considered. A variety of mesh patches, including expanded polytetrafluoroethylene (ePTFE), polypropylene, polyglycolide, and biologics, have been used to close the hernia defect (picture 2) [5,12,15,23-26]. Mesh incorporation promotes chest wall integrity, prevents disruption or migration, and provides mobility for chest wall motion. (See "Surgical management of chest wall tumors", section on 'Chest wall stabilization'.)

●Autologous tissue, including rotational flaps or free flaps, may be necessary for higher-grade (4 and 5) wounds. When rib fixation hardware and/or mesh is utilized for reconstruction and there is not enough healthy soft tissue for wound closure, a flap provides crucial coverage. Soft tissues that are readily available for this area include pectoralis, latissimus dorsi, and rectus abdominus muscle mobilized by a plastic surgeon (figure 1) [27]. (See "Surgical management of chest wall tumors", section on 'Muscle flaps'.)

●Staged definitive repair is recommended when there is wound contamination, especially if a prosthetic will be placed, and when the patient is unable to tolerate the procedure (eg, due to persistent shock) [28].

Mesh fixation — There is no preferred method of mesh placement. An onlay method has been described that anchors the mesh directly to the ribs or adjacent fascia with nonabsorbable sutures [26]. Mesh may be secured in an underlay fashion beneath plated ribs if necessary. (See "Surgical management of chest wall tumors", section on 'Chest wall stabilization'.)

Rib plating — When rib cage hernias are accompanied by multiple rib fractures or a flail chest, reapproximating complex rib fractures can significantly reduce the size of the hernia defect that then requires either tissue or mesh closure. There is no preferred method of rib plating. Various rib fixation devices have been described ranging from absorbable plates secured with suture to metal plates secured with screws to laminar hooks originally designed for spine stabilization surgery [8,29-32]. (See "Surgical management of severe rib fractures", section on 'Plating types and techniques'.)

As with any procedure requiring the placement of prosthetics, the risk of prosthetic infection must be anticipated. Sterile technique, perioperative antibiotic prophylaxis, and removal of any devitalized tissue are critical to reduce this morbidity.

SPECIAL CASES

Costal margin hernias — Traumatic or spontaneous costal margin hernias have been reported [2,3,33]. Costal margin hernias may contain lung or transdiaphragmatically herniated abdominal viscera [5,9,15,34,35]. In the rare event that the hernia involves separation of the costal margin from the thoracic wall or a diaphragmatic hernia, the principles of management above still apply with the addition of diaphragm management.

Costal margins have been reconstructed with reapproximation of the diaphragm and ribs from which it was separated using pericostal and perichondral sutures [33]. Diaphragmatic defects should be repaired based on the size and concern for contamination. If the defect is small and can be reapproximated with minimal tension, then primary repair is indicated. If the defect is large, prosthetic mesh can be placed, but in the setting of possible contamination, biologic mesh is preferred. Alternatively, diaphragmatic transposition is another attractive option for repairing large traumatic defects of the lower chest wall without using prosthetic materials (figure 2) [36].

Pediatric rib cage hernias — Pediatric rib cage hernias are rare, with a systematic review only identifying 16 single case reports [13]. In that study, 63 percent of the pediatric rib cage hernias were treated operatively with primary closure or mesh placement with either an open or minimally invasive approach [13]. Absorbable plates for reduction and fixation of displaced rib fractures are a suitable option since metal plates may require removal as the patient grows [29].

Other cases of closed injury in children can be treated nonoperatively with several weeks of chest wall strapping. One algorithm suggested surgical treatment when there is lung protrusion beyond the rib margins with or without exertion, and when nonoperative management fails [13]. However, this approach has not been validated, due to a general paucity of patients.

OUTCOMES — As traumatic rib cage hernias and chest wall defects are rare, the true risk of individual complications is not known.

Short term — Wound infections, pneumonia, failure to wean off mechanical ventilation, reintubation, recurrent hernia, prolonged air leak, and perioperative death have all been reported [3,5,11]. Given the nature of the injury and extent of tissue mobilization or mesh required for repair, patients may experience chronic decreased range of motion of the chest wall. Rib fracture displacement, hardware dislodgement, hardware infection, and rib osteomyelitis have also been described [37].

Postoperative infections are treated with antibiotics, surgical debridement, removal of prostheses, and delayed autologous tissue reconstruction. Like hernia repairs and reconstructions performed in other body regions, surgical site infections promote recurrent herniation. Additionally, given the fixed structures of the chest wall compared with the abdominal wall, performing a high-tension closure or the use of a more rigid mesh product particularly increases the risk of failure.

Long term — Although most patients with traumatic rib cage hernias and chest wall defects will return to acceptable functional activity or even their preinjury state, patients and families should be counseled that rehabilitation takes many months [5,37]. Fortunately, chronic pain and disability persist beyond one year in only a minority of patients [5,37]. The risk of hernia recurrence is unknown but has been rarely reported.

SUMMARY AND RECOMMENDATIONS

●Etiologies – Traumatic rib cage hernias are rare injuries most commonly caused by motor vehicle crashes in adults and impaled bicycle handlebars in children. (See 'Etiologies, pathogenesis, and epidemiology' above.)

●Presentation – Acute rib cage hernias present with respiratory symptoms given the underlying lung injury. Chronic rib cage hernias often have minimal or no symptoms and just a bulge on exertion. (See 'Presentations' above.)

●Diagnosis – Rib cage hernias can be diagnosed clinically (eg, evisceration through a full thickness chest wall defect) or radiographically (eg, subcutaneous herniation of lung tissue on computed tomography). (See 'Diagnosis' above.)

●Management – Operative management is required for most rib cage hernias in adults, especially open wounds with herniation of lung or abdominal viscera, the repair of which may need to be staged.

Select closed hernias in adults and more commonly in children may be managed nonoperatively with binding and observation. (See 'Management' above.)

●Surgical treatment – The operative approach depends on the severity of injury and includes initial hernia reduction; assessment and repair of the soft tissue and hernia defects; and stabilization of the bony thorax, which often entails rib-plating techniques, followed by coverage of the defect and hernia repair. (See 'Operative management' above.)

●Outcomes – The long-term outcomes of traumatic rib cage hernias and chest wall defects treated operatively are generally good. Chronic pain, significant disability, and recurrence have been reported in a minority of patients. (See 'Outcomes' above.)