Displaced inferior ramus fractures as a marker of posterior pelvic injury.

Abstract

Injuries to the anterior or posterior pelvic ring rarely occur in isolation. Disruption to the anterior pelvic ring, indicated by a fracture of the superior or inferior pubic ramus, or injury to the pubic symphysis, may be indicative of additional pelvic ring disruption. The purpose of this retrospective study was to determine whether displaced inferior pubic ramus fractures warrant a more detailed investigation of the posterior ring in an effort to predict unstable posterior pelvic ring injuries. All patients with a displaced inferior ramus fracture on AP pelvic radiograph were identified at a single level I trauma center over a 5-year period. Complete pelvic radiographs and computed tomography scans were then evaluated for additional pelvic ring injuries. The data were analyzed using the chi-square test to determine the association between inferior ramus fractures and posterior pelvic ring injury. Sixty-three of the 93 patients with a fracture of the inferior ramus (68 %) were found to have a posterior ring injury; 60 % of these injuries were unstable. Patients with concurrent superior ramus fractures were more likely to have a posterior ring injury (p < 0.001) and an unstable pelvis (p = 0.018). Of those with a displaced unilateral inferior ramus fracture, parasymphyseal involvement was associated with higher incidence of posterior ring injury (p = 0.047) and pelvic instability (p = 0.028). The anterior pelvic ring can be used to help identify unstable injuries to the posterior pelvis. Patients with displaced inferior pubic ramus fractures warrant a detailed examination of their posterior ring to identify additional injuries and instability.