ORIGINAL ARTICLE Modified Stoppa Approach for Acetabular Fractures With Anterior and Posterior Column Displacement: Quantification of Radiographic Reduction and Analysis of Interobserver Variability Romney C. Andersen, MD,*† Robert V. O’Toole, MD,* Jason W. Nascone, MD,* Marcus F. Sciadini, MD,* H. Michael Frisch, MD,‡ and Clifford W. Turen, MD* Objectives: To quantify the reduction of acetabular fractures with displacement of the anterior and posterior column by using only a single anterior approach that combines the modified Stoppa approach with the lateral window of the classic ilioinguinal approach. The second objective was to evaluate the interobserver variability of our technique for radiographic evaluation of the reduction. Setting: Level I trauma referral center. Patients: A consecutive cohort of 17 patients with displaced acetabular fractures treated operatively with use of only an anterior approach that combined the modified Stoppa approach with the lateral window of the ilioinguinal approach. To be included in the study, patients had to have at least 5 mm of posterior column displacement and had to have undergone no other approaches. Outcome Measures: Primary outcome was radiographic evidence of reduction as measured by a technique that evaluates five parameters of postoperative reduction. Interobserver variability was evaluated with interclass correlation. Secondary outcomes included operative time, blood loss, and complications. Results: Anatomic reduction of the articular surface was obtained in 14 (82%) patients, imperfect radiographic reduction in three (18%), and poor radiographic reduction in none (0%). Average anterior column displacement improved from 17.5 mm preoperatively to 0.5 mm postoperatively. Average posterior column displacement improved from 13.0 mm to 1.2 mm. Average femoral head medializa- tion improved from 12.5 mm to 1.0 mm. Average quadrilateral surface medialization improved from 15.2 mm to 0.6 mm. Four com- plications occurred in three patients, including one deep infection, one seroma, and two instances of symptoms in the lateral femoral cutaneous nerve. Our technique for grading the radiographic outcome yielded relatively high interobserver reliability preoperatively with interclass correlation values ranging from 0.72 to 0.96 for the five measured parameters. Postoperative reliability was worse. Conclusion: Anatomic or imperfect reduction of certain acetabular fractures involving displacement of both the anterior and posterior columns, even with significant (greater than 5 mm) displacement of the posterior column, can be obtained through the modified Stoppa window and the lateral window of the ilioinguinal approach. The method for evaluating preoperative displacement had excellent reliability. Key Words: acetabular fracture, ilioinguinal approach, Stoppa, interobserver reliability, posterior column, quadrilateral surface (J Orthop Trauma 2010;24:271–278) INTRODUCTION Operative approaches to the acetabulum can be gene- rally classified into anterior, posterior, extensile, and combined approaches. The type and nature of the acetabular fracture substantially influence which approach is used. 1–5 Those fractures with the majority of the displacement occurring anteriorly typically are approached anteriorly, whereas those with the majority of displacement in the posterior part of the acetabulum usually are approached posteriorly. If wide displacement is present in both the anterior and posterior parts of the acetabulum, an extended or combined approach often is used. Although extensile and combined approaches allow improved access to visualize, reduce, and apply instru- mentation to acetabular fractures, they are thought to subject patients to increased morbidity compared with more limited approaches. 1–5 On the other hand, more limited exposures might not allow adequate visualization for reduction and instrumentation of complex fracture patterns. Letournel 6 described the ilioinguinal approach to the acetabulum, and it often is used for anterior column, anterior wall, anterior column with posterior hemitransverse, and cer- tain associated both-column, transverse, and T-type fractures with anterior displacement greater than posterior displace- ment. Limitations to the approach include difficulty in reducing and applying instrumentation to the posterior column and quadrilateral surface. Accepted for publication June 12, 2009. From the *R Adams Cowley Shock Trauma Center, Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, MD; the †Walter Reed National Military Medical Center, Bethesda, MD, and Washington, DC; and ‡Mission Hospital, Asheville, NC. No funds were received in support of this work. Reprints: Robert V. O’Toole, MD, 22 S. Greene Street, T3R62, R Adams Cowley Shock Trauma Center, Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, MD 21201 (e-mail: rvo3@ yahoo.com). Copyright Ó 2010 by Lippincott Williams & Wilkins J Orthop Trauma  Volume 24, Number 5, May 2010 www.jorthotrauma.com | 271