Predicting the Poor Clinical and Radiographic Outcomes after the Anatomical Reduction and Internal Fixation of Posterior Wall Acetabular Fractures: A Retrospective Analysis.

Anatomical reduction is the fundamental principle of hip function restoration after posterior acetabular wall fractures (PWFs). Some patients exhibit poor outcomes despite anatomical reduction, and the prognostic factors leading to poor outcomes remain elusive. This study aimed to investigate the clinical and radiographic outcomes in patients with PWFs who had undergone anatomical reduction and internal fixation and to identify the predictors that impair clinical and radiologic outcomes. The clinical records of 60 patients with elementary PWFs who had undergone anatomical reduction and internal fixation between January 2005 and July 2015 were reviewed retrospectively. The Harris hip score (HHS) and modified Merle d'Aubigné clinical hip scores (MMAS) were used to evaluate the clinical outcome. Preoperative and final follow-up radiographs were cross checked to identify poor radiographic outcomes that included the presence of advanced osteoarthritis and osteonecrosis, as well as the need for conversion to total hip arthroplasty. Acetabular dome comminution was assessed from computerized tomography, and the outcomes were further evaluated according to the involvement of fragment comminution. The fracture comminution and age were negatively correlated with functional outcomes (correlation coefficients were -0.41 and -0.39 in HHS and MMAS, respectively) and were significantly related to the severity of osteoarthritis and osteonecrosis as well as the need for total hip arthroplasty. Regarding the radiographic factors, significantly worse post-operative HHS and MMAS were found in the fracture comminution group. In the subanalysis of the status of fracture comminution, patients with fragment comminution involving the acetabular dome had significantly lower functional scores than those with other fracture patterns. In conclusion, age, fracture comminution, and dome comminution were the prognostic indicators of advanced osteoarthritis and poor functional scores after the anatomical reduction and internal fixation of PWFs. We emphasized the relevance of acetabular dome comminution as an important contributing factor to clinical and radiographic outcomes.