Combined injuries of the pelvis and acetabulum: nature of a devastating dyad.

OBJECTIVES: To describe the clinical characteristics of combined injuries of the pelvis and acetabulum, which have not been previously described. We hypothesize that this combination of injuries affects not only the postinjury hemodynamics of the patient, but the outcome of subsequent acetabular fracture treatment.

DESIGN: Retrospective study.

SETTING: Level I trauma center.

METHODS: The data collected included patient demographics, fracture classification, Injury Severity Score, systolic blood pressure on arrival, amount of packed red blood cells transfused, time to operation, perioperative complications, and radiographic outcomes. Age- and sex-matched control groups of patients with pure pelvic fractures and pure acetabular fractures were compared with the combined injury group to assess injury severity characteristics. To determine the independent factors influencing the postoperative residual displacement of the acetabulum, multiple linear regression analysis was used.

RESULTS: Between January 1, 1998, and December 31, 2007, there were 1612 patients with either pelvic or acetabular fractures requiring admission to our institution, of which 82 (5.1%) had the combination of an unstable pelvic injury (Orthopaedic Trauma Association [OTA] 61 Types B/C) and a displaced acetabular fracture (OTA 62). Eighty-two patients with an isolated unstable pelvic injury and 82 patients with an isolated displaced acetabular fracture were chosen from the same study period to act as control groups. Patients in the combined group were significantly more injured as compared with the displaced acetabular fracture control group with regard to Injury Severity Score (P < 0.001), systolic blood pressure (P < 0.001), and packed red blood cells (P < 0.001). In the combined group, the most common pelvic fracture patterns were OTA 61.B1 and B2. Transverse-type acetabular fractures patterns (OTA 62.B1 and B2) accounted for 61.2% of all acetabular fractures in the combined group. The most frequent injury combination was a transverse-type acetabular fracture with an associated ipsilateral anterior disruption of the sacroiliac joint. Sixty-eight patients underwent surgical intervention at a mean time of 5.7 days. The mean postoperative displacement of acetabular fracture reduction was 2.2 mm as evaluated by radiographs. Multiple regression analysis revealed that the amount of postoperative posterior pelvic displacement, Type B2 acetabular fractures, and patient age were significant predictors of the amount of residual acetabular displacement found postoperatively.

CONCLUSION: Patients with combined pelvic and acetabular fractures represent a serious injury that includes the resuscitative challenges of pelvic injuries coupled with the difficulties of precise reduction of acetabular fractures. To obtain optimal reduction of the acetabulum, initial accurate reduction of the posterior pelvic lesion appears to be necessary.