Association of injury mechanism with the risk of cervical spine fractures.

OBJECTIVE A full understanding of an injury event and the mechanical forces involved should be important for predicting specific anatomical patterns of injury. Yet, information on the mechanism of injury is often overlooked as a predictor for specific anatomical injury in clinical decision-making. We measured the relationship between mechanism of injury and risk for cervical spine fracture. METHODS Our case-control study is a secondary analysis of data collected from the Canadian C-Spine Rule (CCR) study. Data were collected from 1996 to 2002 and included patients presenting to the emergency departments of 9 tertiary care centres after sustaining acute blunt trauma to the head or neck. Cases are defined as patients who were categorized in the CCR study with a clinically important cervical spine fracture. Controls had no radiologic evidence of cervical spine injury. Bivariate and multivariate unconditional logistic regression models were used. Results are presented as odds ratios (ORs) with 95% confidence intervals (CIs). RESULTS Among the 17,208 patients in the CCR study, 320 (2%)received a diagnosis of a cervical spine fracture. Axial loads, falls, diving incidents and nontraffic motorized vehicle collisions (e.g., collisions involving snowmobiles or all-terrain vehicles) were injury mechanisms that were significantly related to a higher risk of fracture. For motor vehicle collisions, the risk of cervical spine injury increased with the posted speed, being involved in a head-on collision or a rollover, or not wearing a seat belt (p < 0.05). The occurrence of cervical spine fracture was negligible in simple rear-end collisions (1 in 3694 cases; OR 0.015, 95% CI 0.002-0.104]). CONCLUSION Our study quantitatively demonstrates the relationship between specific mechanisms of injury and the risk of a cervical spine fracture. A full understanding of the injury mechanism would assist providers of emergency health care in assessing risk for injury in trauma patients.