Relationship of Sacral Fractures to Nerve Injury: Is the Denis Classification Still Accurate?

Objective: Use modern computed tomographic imaging to reassess neurological injury risks associated with zone I-III sacral fractures as originally described by Denis et al. Design: Retrospective case-control study. Setting: University Level I Trauma Center. Patients/Participants: One thousand five hundred seven consecutive patients who presented with sacral fractures between January 2000 and August 2012. Main Outcome Measurements: Patients were stratified based on the diagnosis of acute neurological injury. The risk of severe and complex sacral fractures based on the presence of nerve injury was assessed. Results: The rate of nerve injury was significantly lower compared with historic data (3.5% vs. 21.6%, P<0.001). Acute nerve injury was a significant risk factor for displaced (odds ratio [OR]: 8.4, 95% confidence interval [CI], 1.4-51.9) and comminuted (OR: 5.2, 95% CI, 1.7-16.3) sacral fractures as well as zone II (OR: 3.4, 95% CI, 1.1-10.1) and III (OR: 3.9, 95% CI, 1.0-16.4) fractures. Conclusions: The incidence of nerve injuries associated with sacral fractures is significantly lower than originally published by Denis et al. Patients with a nerve injury were highly correlated with having a displaced, comminuted, or zone III fracture, or spinopelvic dissociation; the authors recommend a fine cut computerized tomography for further investigation if these findings are not apparent on initial radiographic imaging.