Outcomes of posterior wall fractures of the acetabulum

Background: The Musculoskeletal Function Assessment (MFA) is a validated, reliable, self-administered questionnaire that is useful for determining functional status. The Merle d'Aubigne score is a clinical measure of hip function. The purpose of the present study was to evaluate the outcome information provided by these two instruments after operative treatment of elementary posterior wall fractures of the acetabulum. Methods: Forty-six patients who had been followed for a minimum of two years after operative treatment of an elementary posterior wall fracture of the acetabulum were included in the study. Functional outcomes were assessed with use of the ten individual indices and total score of the MFA, and clinical outcomes were evaluated with use of the Merle d'Aubigne score. The MFA scores were compared with previously reported normative values and with previously reported values for similar patients with hip injuries. The duration of follow-up ranged from two to fourteen years (mean, five years). Results: The mean Merle d'Aubigne score was 17 (standard deviation, 1; range, 14 to 18), indicating overall good-to-excellent clinical results. However, the mean total MFA score was 23.17, which was significantly worse than the normative mean of 9.26 (p < 0.001). All MFA indices except hand/fine motor were similarly significantly worse than expected norms. The mean MFA total score was statistically similar to that reported by others for patients with hip injuries. The emotional category of the MFA score was found to be an important determinant of the total score. The Spearman rho correlation coefficient between the Merle d'Aubigne score and the MFA score was -0.62 (p < 0.001). However, the Merle d'Aubigne score data were asymmetric, demonstrating a ceiling effect (crowding of the scores at the upper end of the scale, limiting the ability of the score to demonstrate differences between patients with supposedly better clinical outcomes). Conclusions: The total MFA scores for patients with a posterior wall fracture of the acetabulum were significantly worse than normative reference values. Thus, complete recovery after a posterior wall fracture of the acetabulum is uncommon, with residual functional deficits involving wide-ranging aspects of everyday living that do not necessarily have an obvious direct connection to hip function. Although the modified Merle d'Aubigne score may be useful for evaluating isolated hip function in patients who have been treated for an acetabular fracture, its shortcomings limit its usefulness as a method for evaluating functional outcome in these patients. Research efforts should be directed toward the identification of the psychosocial and other underlying determinants of functional outcome and potential related treatment interventions.