Occult injuries of the contralateral sacroiliac joint in operatively treated pelvis fractures: incidence, root cause analysis, and proposal of treatment algorithm.

PURPOSE: To determine the most common injury patterns, root cause, and the frequency with which unrecognized contralateral posterior ring injury occurs in patients presenting with surgically treated pelvic fractures.

METHODS: The medical records of 73 patients presenting to our level I trauma center (52 male and 21 female patients; mean age 41.8 years; range 18-89 years) with surgically treated pelvic ring fractures between January 1, 2016 and January 1, 2018 were reviewed. Patient demographics, mechanism of injury, associated injuries, imaging prior to binder or external fixation, use of temporary stabilization with pre-peritoneal pelvic packing (PPP) and anterior pelvic external fixation, and fracture pattern were recorded and analyzed to identify independent risk factors contributing to occult contralateral missed posterior ring injury.

RESULTS: Occult contralateral pelvic ring injuries occurred in 6/72 patients (8.2% incidence). Pelvis fractures in multiply traumatized patients with associated orthopaedic injuries were associated with higher prevalence of occult contralateral pelvic ring injury (relative risk 1.85, 95% CI 1.13-3.02) as compared to patients with isolated pelvic fractures.

CONCLUSIONS: There is an 8.2% incidence of unrecognized contralateral SI joint instability in patients presenting with unstable pelvic ring injuries. Multiply traumatized patients with multiple orthopaedic injuries were an independent risk factor for this injury pattern.