ORIGINAL ARTICLE Combined Pelvic Ring Disruption and Acetabular Fracture: Associated Injury Patterns in 40 Patients Greg M. Osgood, MD, Theodore T. Manson, MD, Robert V. O’Toole, MD, and Clifford H. Turen, MD Objectives: Combined pelvic ring disruptions and acetabular fractures are thought to be uncommon. Our objectives were to characterize concomitant injury patterns and to compare them with historically observed rates for each injury in isolation. Design: Retrospective review comparing a study group with historical controls. Fracture patterns were compared with our institution’s isolated injury patterns and with isolated injury patterns of other published series. Setting: Level I academic medical center. Patients: Between 1997 and 2001, 854 pelvic ring disruptions and 457 acetabular fractures were evaluated. Forty patients sustained combined injuries. Intervention: None. Main Outcome Measurements: Fracture patterns, Injury Sever- ity Scores, and mortality rates. Results: Our series of combined injuries included 5% posterior wall fractures. This was significantly different from the 30% incidence of posterior wall fractures among isolated acetabular fractures at our institution (P , 0.006). No posterior column or posterior column with associated posterior wall fractures occurred. Fifty-three percent of the patients sustained anterior–posterior compression pelvic ring injuries, exceeding our center’s 19% norm for isolated pelvic ring injuries (P , 0.001). For combined injuries, the mean injury severity score was 27.9 and the overall mortality rate was 13%. Early death occurred in 19% of patients with combined anterior–posterior com- pression injuries and 6% with lateral compression injuries. Conclusions: Patients with combined pelvic and acetabular injuries have multiple system injuries and high Injury Severity Scores. Fracture patterns differ from those observed with isolated injuries. Posterior acetabular fractures are uncommon components. Anterior–posterior compression pelvic injuries seem much more frequent in cases of combined injuries than isolated injuries and are associated with high mortality rates. Key Words: pelvic ring disruption, acetabular fracture, injury patterns, anterior–posterior compression Level of Evidence: Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence. (J Orthop Trauma 2013;27:243–247) INTRODUCTION Combined pelvic ring disruptions and acetabular fractures are thought to be uncommon injuries. Few reports of either pelvic ring disruptions or acetabular fractures have included the combined injuries. 1–4 These reports noted that combined pelvic ring disruptions and acetabular fractures are rare, and the pres- ence of a concomitant acetabular or pelvic fracture often has been an exclusion criterion in previous studies. It has been reported that the combined injuries most often involve lateral compression pelvic ring disruptions and transverse acetabular fractures, 1,2,5 but no specific data have been presented to support the claim. To our knowledge, no previous detailed description of the Young–Burgess 2,6–8 and Letournel 9 classification systems of these combined injuries and no report of morbidity associated with these injuries have been presented in the literature. Similarly, the acetabular frac- ture patterns have not been described. Our study was conducted to characterize concomitant injury patterns and to compare them with historically observed rates for each injury in isolation. We attempted to test the 2 specific hypotheses previously proposed in the literature: (1) lateral compression injury is the most common type of pelvic ring disruption in cases of combined pelvic ring disruptions and acetabular fractures, and (2) transverse acetabular fracture is the most common type of acetabular fracture pattern in cases of combined pelvic ring disruptions and acetabular fractures. PATIENTS AND METHODS After institutional review board approval at our trauma center, we conducted a retrospective review of 2 prospec- tively collected databases of patients who had sustained pelvic trauma. The first database was a fracture database that included International Classification of Diseases, Ninth Revi- sion, code diagnoses and the prospectively assigned classifi- cation of each patient’s pelvic ring disruption and acetabular fracture. The second database was a trauma database that recorded demographic information, injuries, and outcomes of all patients treated at our center. Radiographs and Accepted for publication July 25, 2012. From the R Adams Cowley Shock Trauma Center, Department of Orthopae- dics, University of Maryland School of Medicine, Baltimore, MD. No outside funding or sources of support were received for this work. The authors have no conflicts of interest to report. This study was presented in part at the 2007 Annual Meeting of the American Academy of Orthopaedic Surgeons in San Diego, CA, and at the 2006 Annual Meeting of the Maryland Orthopaedic Association in Baltimore, MD. Reprints: Robert V. O’Toole, MD, R Adams Cowley Shock Trauma Center, Department of Orthopaedics, University of Maryland School of Medicine, 22 S. Greene St, Room T3R62, Baltimore, MD 21201 (e-mail: rvo3@ yahoo.com). Copyright © 2013 by Lippincott Williams & Wilkins J Orthop Trauma  Volume 27, Number 5, May 2013 www.jorthotrauma.com | 243