Thoracolumbar junction injuries after motor vehicle collision: are there differences in restrained and nonrestrained front seat occupants?

OBJECT

Motor vehicle collision (MVC) is one of the most common causes of thoracolumbar junction (TLJ) injury. Although there is little doubt that the use of seat belts reduces the incidence and severity of TLJ injury after MVC, the mechanism by which this is protective against TLJ injury for drivers and passengers is relatively unknown.

METHODS

Thirty-nine patients with TLJ (T11-L2) injury who were front seat occupants of a four-wheeled vehicle at the time of MVC (frontal crash) were admitted between 2000 and 2004. The 39 patients were divided into two groups: 18 who had been restrained and 21 who had not been restrained at the time of the MVC. Patient demographics, including the mean Injury Severity Scale score, incidence of neurological deficit, level of TLJ injury, and type of TLJ injury according to the Denis classification were compared.

RESULTS

The incidence of neurological deficit in the restrained group was significantly lower compared with the nonrestrained group (5.6% compared with 33.3%, p < 0.05). The incidence of flexion-distraction/fracture-dislocation injuries in the restrained group was also significantly lower (0.0% compared with 33.3% in the nonrestrained group, p < 0.01). The restrained group was significantly older (37.4 +/- 3.6 years compared with 28.0 +/- 2.5 years in the nonrestrained group, p < 0.05), but otherwise there were no significant differences between the two groups regarding the patients' demographic data.

CONCLUSIONS

It is likely that the high incidence of neurological deficit in the nonrestrained front seat motor vehicle occupants who had a TLJ injury was mostly due to the high incidence of flexion-distraction/fracture-dislocation injuries. This retrospective study indirectly shows the efficacy of three-point seat belt systems in reducing the severity of a TLJ injury after an MVC. Compression/burst fractures still occur in restrained front seat occupants, however, and elucidation of the injury mechanism of such axial loading fractures may be important to improve safety further for automobile occupants.