This study indicates that hyperextension fractures of the thoracic spine may result in high injury severity and overall life-threatening thoracoabdominal injuries once the lower ribs at the costal margin show a fracture at the same time. As suspected, injuries to the costal arch can act as an indicator of severe trauma, especially in this context.
Caused by high-energy accidents, all of our patients suffered a hyperextension fracture of the central thoracic spine in the thoracic vertebrae regions 7–9. The energy apparently continued over the intercostal space to the costal arch. The intercostal space tore together with the thoracic spine; the energy was diverted in the costal arch between levels 7 and 9, i.e., at the ribs’ point of confluence. This created an unstable situation for the anterior and lateral chest wall. This injury pattern is analogous to the one described in the literature in the case of a rupture of the spinal column with an anterior rupture of the chest wall due to the tearing of the sternum (5–7). In our three cases, the rupture of the intercostal space resulted in a herniation of the lung parenchyma into the chest wall. In each case, the diaphragm was torn out at the costal arch to create a two-cavity injury.
Although two patients suffered further life-threatening injuries, which had to be addressed as an emergency, the outcomes were good. The only patient who was unable to work again had a bilateral chest trauma with remaining limited capacity. It should be noted here that the left operated side showed a significantly better function than the conservatively treated right side, which initially appeared to be less severely injured. We see this as a supporting argument for our treatment recommendation that surgical stabilization of the thorax should be generously indicated for this severe combined injury entity. Although the literature remains somehow controversial to surgical repair of rib fractures in general, we believe that there are significant advantages to surgical intervention, such as reduced respiratory failure (11–14). Recent studies support our estimation of a beneficial operative therapy strategy, especially in analogous severe thoracic traumata as in flail chest or costoclavicular injuries (11, 15–22). For other, similar injury patterns with e.g. transdiaphragmatic intercostal hernia and other costal margin injuries, equivalent therapeutic strategies as in our cases were used (23–25).
The peculiarity of the injury combination of a distraction injury to the thoracic spine plus a fracture of the costal arch is above all the risk of two major accompanying injuries: an intercostal tear with consecutive lung herniation and a diaphragmatic tear leading to a consecutive two-cavity injury. The indicator function for a severe trauma is again underlined: despite the severity of the associated injuries, two-cavity traumata and particularly diaphragmatic injuries are often diagnosed only secondarily and delayed (23, 24).
An associated high ISS in case of an unstable costal arch injury combined with a distraction fracture of the thoracic spine could be attributed to the high injury severity of the thorax itself, since serial rib fractures in monolateral injuries are already related to AIS 3 and 4 (9). However, we were able to show that there are also other severe concomitant injuries that are of considerable importance for the overall injury severity. This is underlined by the high overall ISS values with 57, 41, and 20 points which is in the majority significantly higher than the inclusion criterion of ISS ≥ 16.
Due to the low number of cases, the findings reported here should be interpreted cautiously. As in every retrospective evaluation, causal conclusions cannot be drawn. Since our selection criteria was ISS ≥16 due to the high AIS values of the respective single injury, only severely injured patients were analyzed. Further research should investigate the relevance in low-energy accidents, e.g. in geriatric collectives, in order to double-check a possible underestimation in the frequency of this injury entity. Also, further prospective studies with larger sample sizes should attempt to validate our recommended therapeutic strategies. However, case-related clinical details can be analyzed and in each case history involving the fracture kinetic and morphological aspects, which is an advantage of our study in contrast to register studies with large cohorts.