Introduction

Unintentional injuries are the third leading cause of death worldwide after cardiovascular diseases and cancer. Chest trauma accounts for 25% of trauma-related deaths. Chest wall injuries are the most common types of blunt chest trauma (70%) and rib fractures are their most conspicuous expression. Chest wall injuries occur mainly in motor vehicle accidents, are frequently accompanied by visceral injury (particularly lung contusion), have high mortality rate and result in prolonged periods of work absence^1-3.

Patterns of injury

Flail chest involves two or more consecutive rib fractures in two or more places, resulting in paradoxical respiration. In fact, it is a clinical sign that determines a mechanism of respiratory failure that occurs in 10% of chest injuries and may reach a mortality rate of 42% when it is associated with lung contusion^1,2,5. Flail chest generally involves four to eight ribs. Anterior rib fractures are more serious and may involve both hemithorax. The diagnosis is mainly clinical by visualizing the paradoxical motion of the area involved, which can be difficult to recognize in ventilated patients. The imaging tests contribute to characterize the patterns of injury, evaluate the associated injuries and plan surgery⁶.

Multiple non-flail rib fractures can constitute complex and serious injuries, determining per se a biomechanical failure of the chest wall that compromises the respiratory function. Borrelly coined the term traumatic failing chest (anatomic and functional)⁷.

Multifactorial respiratory failure is the final common pathway of major chest trauma. The factors that contribute include severe pain that limits breathing and effective coughing, impaired chest wall compliance and function of the muscles of respiration, increased and ineffective respiratory work, hemopneumothorax and lung contusion. In summary, biomechanical failure of the chest wall.

Evolution of treatment throughout history

In the early fifties, the surgical efforts were aimed only at treating the fractures (immobilization, traction, etc.). During the sixties and early seventies, the associated injuries were prioritized, and the recommendations included tracheostomy and mechanical ventilation (MV). As many patients had concomitant lung contusion and improved after two to three weeks of ventilation while the flail was stabilized, mechanical ventilation was erroneously interpreted as the treatment of choice for flail chest and was called internal pneumatic stabilization. In 1975, the studies by Trinkle shed light on this issue using an approach based on restriction of intravenous fluids, pain management, non-invasive ventilation, intensive physiotherapy and treatment with corticosteroids, which proved to reduce hospitalization and mortality⁸. However, in cases of severe respiratory failure secondary to lung contusion, MV is mandatory^8,9.

It is interesting to mention the social and labor consequences reported by the survivors: 75% complained of chest pain and 38% had experienced moderate to severe changes in their work activity. In addition, 57% had abnormal spirometries with restrictive changes in 33%¹⁰.

Rationale for osteosynthesis

This work was the starting point for a renewed interest in skeletal injuries and surgical fixation using Kirchner wires, Judet struts, prosthetic ribs made of acrylic developed by Crosa, Borrelly plates, and modern titanium prostheses^7-9,11. The benefits in terms of mortality, shorter length of hospital stay and complications were observed since the first reports were published. The limitations at the long-term also improved. The study by Tanaka set the turning point; it was the first randomized, prospective study performed in flail chest patients who required mechanical ventilation comparing the differences between those who underwent surgical treatment and those who did not¹². Both groups were treated with a standard protocol of MV, analgesia and pulmonary physiotherapy for 5 days. On day 5, those patients who persisted in MV were randomly assigned to one group or the other. The patients who underwent rib fixation had better and statistically significant outcomes, with shorter ventilatory period and intensive care unit (ICU) stay. The vital capacity was also significantly better. These findings were confirmed by subsequent studies¹³.

While most trials have focused on flail chest, some more recent studies have focused on non-flail rib fractures and their association with long-term complications. There is a general agreement that early fixation of non-flail rib fractures reduces the development of complications such as retained hemothorax, empyema, pneumonia and distress. This is more evident in patients > 65 years; for this reason, the indication of osteosynthesis in more common in this age group^13,14. In a retrospective study, Bulger et al. found that elderly patients with blunt chest trauma and rib fractures had twice the mortality and thoracic morbidity of younger patients with similar injuries¹⁴. For each additional rib fracture in > 65 years, mortality increased by 19% and the risk of pneumonia by 27%. These data strengthen the interest in rib fixation, especially in elder patients.

Conceptually, osteosynthesis is just a surgical procedure intended to restore the normal anatomy of the rib cage and the respiratory mechanics^15,16.

Current indications for rib fixation

Rib fixation is indicated in the following situations:

1. Extensive injuries of the anterolateral chest wall (traumatic thoracoplasty, severe flail chest, ribs impacting into the thorax, extensive loss of chest wall substance, significant loss of lung volume, and bilateral fractures with sternal fracture)

2. On the way out after thoracotomy.

3. Inadequate pain management.

4. Progressive impairment of gas exchange in the absence of lung contusion.

5. Failure to wean from mechanical ventilation.

There is increasing consensus to perform rib fixation when there are more than 3 displaced fractures, even in non-flail chest patients but with pulmonary restriction > 50%.

In addition to the advantages previously mentioned, patients with rib fixation have shorter mechanical ventilation time, and therefore lower incidence of pneumonia, shorter length of ICU stay and of hospital stay, less pain, and better functional recovery and return to work.

However, the level of evidence is still moderate.

Not all the patients with any of these indications deserve osteosynthesis. Internal rib fixation is contraindicated in case of hemodynamic instability, severe contusion, severe pneumonia, severe closed head or spinal cord injury and intrathoracic infection.

As already mentioned, age is not a contraindication; on the contrary, it is a factor that favors early fixation. Elderly patients get exhausted quite rapidly and have no biological or functional reserves to be weaned early or to overcome complications.

We prefer to perform the osteosynthesis during the first week. Late fixation may be necessary in carefully selected patients for chronic disabling pain, wall hernias or severe restriction, although these rare situations are highly controversial and should be carefully evaluated.

Technical considerations

Three-dimensional computed tomography is useful to characterize the injury pattern and to plan surgery. It also allows the diagnosis of the associated lung and bone injuries (pneumonia, pleural effusion, lung contusion, and fractures of the spine, clavicle and scapula).

Fixation is performed under general anesthesia and usually with conventional orotracheal intubation, which allows for proper airway suctioning. In stable patients in specific cases of more limited injuries undergoing video-assisted procedures, selective bronchial intubation or the use of bronchial blockers have been proposed.

The position of the patient depends on the extension and location of the fractures.

The incision depends on the ribs involved. Rib fractures are usually located by three-dimensional computed tomography and during intraoperative exploration, while some surgeons use ultrasound. Posterolateral thoracotomy is still the standard incision although the current trend is to make more limited incisions. Those incisions which avoid muscle section are recommended as long as they do not hinder or compromise the result of the exploration or fixation.

The use of VATS has been proposed before performing the procedure in selected patients. The advantages of VATS are the possibility of exploring the pleural cavity, evacuating effusions and ruling other associated lesions. It is also useful for locating displaced fractures and decide the site of the incision. Yet, it is not applicable to all the patients. The advantage of muscle-sparing thoracotomy is minimized in those who have already suffered a serious trauma; however, there are cases in which it is fully justified.

We have gained considerable experience with the use of the prosthetic ribs made of acrylic developed by Crosa¹¹ which are currently being replaced by modern prostheses. Their high cost is the main inconvenience. Titanium plates or stainless-steel plates are most commonly used, and they are available in different sizes and with different fixation systems.

Although there are no studies suggesting the superiority of one device over the other, precontoured titanium plates with self-tapping bicortical screws are the most used in our environment, placed on the external surface of the rib.

The 4th-10th ribs are the most commonly fractured and produce the greatest anatomic and functional impairment. As they are the most mobile ribs, they produce a significant amount of pain. Some surgeons repair all the ribs fractured; however, we recommend performing osteosynthesis only of those ribs with severe displacement. When the ribs are broken in two different sites (flail chest, for example), the recommendation is to stabilize both fracture lines in order to restore the adequate stability of the chest wall and to reduce the associated complications. In general, only one plate is used per broken rib, although we have used two plates in cases of very distant fractures. If the fractures are anterior or involve the costal cartilage, it may be necessary to anchor plates to the sternum or the contralateral hemithorax. Fixation of those ribs involved during thoracotomy is not necessary as they are usually fixed when the incision is closed.

The periosteum of the rib should remain in place and not excessively dissected. When using plates, there should be just enough space to reduce the fracture and find a landing zone for the screws on both sides of the fracture line. Three screws are usually placed on both sides. In case of fractures involving the costal cartilage, the plate should be anchored to the sternum and not to the cartilage. Polypropylene seals can be used in these cases or for fixation of osteoporotic ribs. In case of comminuted fractures, we prefer to remove the small bone fragments because they are a source of sequestrum and osteomyelitis. We systematically treat the pleura through the thoracotomy or by thoracoscopy, in order to evacuate the residual hemothorax, which is invariably present. Once the fixation procedure has ended, a drain in placed in the pleural cavity and is removed within the first postoperative days.

The most common postoperative complications are related to the underlying injuries, lung contusion and pneumonia. Hardware infections are rare (1-3%) but may determine removal of the prosthesis even if full stabilization has not been achieved. On certain occasions, we had to remove the hardware due to late infection.

Other complications as hemothorax or empyema are rare when fixation is performed early¹⁵.

Recovery is usually favorable with early extubation, short ICU stay, significant pain relief, early ambulation and usually mild consequences.

In conclusion, rib fixation in thoracic trauma with flail chest or non-flail pattern fractures is a safe procedure that is increasingly used. Its benefits, beyond chest wall stabilization and remodeling, include lower morbidity and mortality, shorter MV time, shorter ICU and hospital stays, lower rate of pneumonias, less pain, and faster functional recovery with earlier return to work. We are convinced that this procedure should be used more frequently.