Modified stoppa approach for acetabular fractures with anterior and posterior column displacement: quantification of radiographic reduction and analysis of interobserver variability.

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 medialization improved from 12.5 mm to 1.0 mm. Average quadrilateral surface medialization improved from 15.2 mm to 0.6 mm. Four complications 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.