Costotransverse screws in repair of paraspinal rib fractures—a novel approach for rib fractures threatening the aorta

Introduction

Fragments of fractured ribs can lacerate the descending thoracic aorta and other mediastinal structures (1). The mortality associated with these aortic lacerations is extremely high. Therefore, awareness, early recognition and prevention are essential for patient survival. Currently, there is no consensus regarding the optimal strategy to prevent these penetrating aortic injuries (2). Prior techniques involved mostly eliminating the sharp rib edge threatening the great vessels (3). However, in the setting of multiple fractured ribs or an unstable chest, these techniques become problematic. Currently, threatened aorta by proximal rib fractures is not an indication for surgical stabilization of ribs (4). Additionally, plating ribs requires a landing zone on each side of the fracture for the recommended placement of three screws (5). In very proximal rib fractures, often there is not enough landing zone to accommodate three screws. We are reporting a case of open reduction internal fixation (ORIF) of paraspinal rib fractures to prevent penetrating aortic injury along with a review of the relevant literature.

Case presentation

A 21-year-old woman was struck by a train at high speed. At the scene, her blood pressure was 78/52, and pulse range was 140–160 bpm with an initial Glasgow Coma Scale of 15. She was transported to a local hospital where intubation and tube thoracostomy were performed for respiratory distress. Imaging revealed numerous left sided rib fractures and a left pneumothorax. With ongoing resuscitation, she was airlifted to our level one trauma center for further management. Further workup revealed multiple injuries (Table 1). Her past medical history was significant for bipolar disorder, major depressive disorder, anxiety and polysubstance abuse.

Table 1 Injuries
Full table

After arrival to our trauma center, she remained unstable and underwent an emergent exploratory laparotomy, splenectomy and external fixation of extremity fractures. She remained intubated and ventilated after the procedure in the surgical intensive care unit (SICU). Rib plating was initially considered given her flail chest, but this idea was quickly abandoned because of the proximity of the fractures to the spine. The distance between the closest fractured rib (left posterior 5^th rib fragment) and the aorta on admission computed tomography (CT) scan was approximately 23.4 mm. On hospital day five, during a subsequent survey of her injuries by the SICU team, the proximity of the fractured rib fragments to the aorta was reappraised and determined to be a threat to the aorta. A repeat CT scan of the chest was performed to further assess the rib fractures (Figures 1,2). Immediate “do-not-turn the patient” orders were placed to minimize the risk of penetrating aortic injury. Vascular surgery was consulted the same day, and a computed tomography angiography (CTA) scan was performed to ensure that an aortic injury had not already occurred. On that CTA scan, multiple left-sided rib fragments, including the 5^th were now as close as 6.5 mm from her aorta (Figures 1,2).

Figure 1 3D CT reconstruction of the chest on the left showing the flail pathology and paraspinal rib fractures threatening the aorta. On the right an axial CT cut is showing the proximity of the sharp fractured distal fragments of the left 5^th rib to the aorta by a mere 6.5 mm.

Figure 2 3D reconstruction of the chest (superior view) show in the sharp fracture ends of the left 4^th and 5^th ribs being very close to the descending aorta.

Given the proximity of the rib fragments to the aorta, flail chest and respiratory failure, she was taken to the operating room on hospital day six for rib repair. Neurosurgery was consulted to assist in the manipulation of the vertebrae. The patient was placed in right lateral decubitus position while video-assisted thoracoscopic surgery (VATS) was performed with evacuation of retained hemothorax and survey of injuries. The fractured ribs were easily visualized in the thoracic cavity and were confirmed to be near the patient’s aorta, without aortic injury. A vertical paraspinal incision was then made and carried posterolaterally around the scapula. After muscle dissection, the scapula was elevated off the ribcage, exposing the rib fractures. Posterior fractures in rib 7, followed by 8, 9, and then 5 and 6 were fixed with titanium locking osteosynthesis plates using the MatrixRIB^® system (5). Please note that ribs 5 and 6 each received two costotransverse screws (Figures 3-5) placed in the corresponding ribs and transverse processes. Anterior rib fractures in ribs 7, 8, and 9 were also plated. The patient was subsequently extubated on post-operative day one, or hospital day seven. She was transferred to the floor on post-operative day three and discharged to a rehabilitation center 23 days after presentation.

Figure 3 Axial CT of the chest illustrates the two costotransverse process screws used in surgical fixation of the 5^th rib fracture. Note: this CT scan also demonstrates compressive atelectasis and hemothorax due to an unrelated trauma 19 months after initial presentation and surgical stabilization of rib fractures.

Figure 4 This schematic depicts the screw path (A) in relationship to the intercostal neurovascular bundle (B). The sagittal angle (C) is safer when maintained between 50°–70° from the frontal plane. Adapted with permission from Xu et al.

Figure 5 Relationships between the costotransverse joint, the costotransverse screws [2 and 3], the plate and the vertebral foramen. The screws are directed outward away from the vertebral body. For a safe path, an angle of 0° [1] to about 45° [3] from the sagittal plane must be maintained. Adapted with permission from Xu et al.

Discussion

By proactively reducing and fixing this patient’s fractured ribs, we not only helped mitigate respiratory failure, but also prevented a potential aortic puncture. The patient’s posterior rib fractures with sharp boney edges were an imminent threat to the descending thoracic aorta. Comparison between the patient’s CT scans gave clear evidence of shifting sharp distal rib fragments towards the aorta. Movement of these fragments is larger during positional changes, such as turns or getting out of bed, putting the aorta at greater risk of injury during the abovementioned activities (1,6,7). Therefore, patients with very posterior rib fractures should be assessed for fracture patterns that could lead to impalement of nearby vital structures. Once the potential for injury is established, we find it prudent to limit movement until surgical stabilization could be achieved. According to O’Conor et al., traumatic injury to the aorta carries a 99% mortality rate without surgical intervention, and only 15% of patients will survive the first hour after injury (2).

Chest CT is an essential clinical tool that should be utilized in evaluating rib fractures and their potential for causing aortic laceration. However, it is imperative to review the CT with the injury pattern reported in mind. In one case, a patient died of a penetrating aortic injury from the sixth rib in which an improper reading of the chest CT was reported (8). Delayed presentations have been reported with similar injuries for up to fourteen days (9).

According to our literature review, the most common predisposing injuries are posterior left sided rib fractures involving ribs 4–11, most commonly 6, 7, or 8 as seen in Table 2. Cases of anterior right sided rib fractures have been described as well yet are less common (2). Mechanisms of injury are mostly blunt chest trauma, including falls, motor vehicle crashes, struck pedestrians, and crush injuries.

Table 2 Relevant literature review
Full table

Surgical interventions have focused on a symptomatic approach, repairing the aorta after the injury has already occurred. Techniques have included filing, rongeuring, or resecting the jagged rib to prevent further sequelae. Operative intervention has been suggested in the literature in the setting of a left sided rib fracture threatening the aorta (12). However, only two prior case reports have focused on using surgical intervention as a preventative technique, one performed open reduction with internal fixation and the other using rib removal (12,19). We strongly suggest that an ORIF approach to rib fractures with the potential of causing aortic injury be considered in the management of these patients. This is particularly true in the setting of multiple rib fractures, flail chest, respiratory failure, and intractable pain given the mounting evidence from prospective studies. Surgical stabilization of fractured ribs is emerging as a very useful tool in thoracic trauma. These studies indicate that operative fixation of rib fractures lead to shorter intensive care unit (ICU) stays and better pulmonary outcomes compared to non-operative management (4,20,21). The outcomes and timing of ORIF for rib fractures in polytrauma patients require further study (22).

It is generally recommended to place three screws on each side of the fracture when performing ORIF (5). However, circumstances imposed us not only to place a limited number of screws but also to use an alternative structure to achieve fixation. This case demonstrates that when there is not sufficient landing zone posteriorly, the transverse process is an appropriate site for fixation. More rigid fixation is achievable by inserting the screw through the transverse process, across the costotransverse joint and into the dorsal cortex of the rib (23). This is the first case to our knowledge where posterior rib fractures were plated with screws placed through the transverse process adjacent to the rib. It has generally not been recommended to repair very posterior rib fractures due to the complex anatomy and the proximity to the spine (24). However, by their morphology, thoracic transverse processes are amenable for screw insertion (25). The costotransverse joint is a synovial joint ensheathed in a capsule and adjacent ligaments. The joint involves the thoracic vertebral body, the costal tubercle, and the transverse process. Care should be taken to avoid the neurovascular bundle which runs in the costal transverse space by directing the screws parallel to about 45 degrees to the sagittal plane and cephalad 50–70 degrees relative to the frontal plane (23) (Figure 4). Failure to direct the screw properly can result in injury to the neurovascular bundle and violation of parietal pleura. To further minimize risks, it is important to bear in mind that the boney purchase of the transverse process plus the dorsal cortex of the rib in the thoracic region is estimated to be around 13 mm. Loss of articulation of the costovertebral and costotransverse joints is expected, yet the effect on respiratory function is unknown.

Conclusions

Rib plating is effective in preventing a jagged edge of a fractured rib from penetrating great vessels. Costotransverse screw placement is feasible and an appropriate technique for management of paraspinal rib fractures. We propose early surgical intervention for patients who have posterior rib fractures in the left chest to prevent the development of aortic injury.

Acknowledgements

Marco Vitto, MD from Albany Medical Center Department of Radiology for technical assistance.

Footnote

Conflicts of Interest: D Bonville and M Tafen are paid consultants for DePuy Synthes. This study was presented at the 2018 Chest Wall Injury Summit of the Chest Wall Injury Society, March 2–4, 2018, in Park City, UT.

Informed Consent: Written informed consent was obtained from the patient’s legal authorized representative for publication of this manuscript and any accompanying images.

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