Results of Operative Treatment of Fractures of the Posterior Wall of the Acetabulum

Background: The purpose of this study was to determine the clinical outcome in patients in whom a displaced fracture of the posterior wall of the acetabulum had been treated by open reduction and internal fixation. Methods: One hundred patients who had had open reduction and internal fixation of an unstable unilateral fracture of the posterior wall of the acetabulum were studied. Ninety-four patients were assessed at a mean of five years (range, two to fourteen years) after the injury. Six patients with a poor result were followed for less than two years. The functional outcome was evaluated with use of the clinical grading system adopted by Letournel and Judet with incorporation of modifications by Matta. Patient, fracture, and radiographic variables were analyzed to identify possible associations with functional outcome. Results: The reduction of the fracture, as determined with plain radiography, was graded as anatomic in ninety-seven patients and as imperfect in three. The clinical outcome at the time of final follow-up was graded as excellent in fifty-five patients, very good in twenty-five, good in nine, fair in one, and poor in ten. The radiographic result was excellent in eighty-one patients, good in five, fair in four, and poor in ten. There was a strong association between the clinical outcome and the final radiographic grade. Variables identified as risk factors for an unsatisfactory clinical result included a delay of greater than twelve hours before reduction of an associated hip dislocation, an age of fifty-five years or older at the time of injury, intra-articular comminution, and osteonecrosis. Conclusions: The uncomplicated radiographic appearance and relatively simple operative approach for fractures of the posterior acetabular wall belie the risk of poor results. Prompt reduction of an associated hip dislocation is imperative. Fractures in elderly patients and those with extensive comminution are more likely to have a poor clinical result. However, a high likelihood of a long-term good-to-excellent result can be expected following anatomic reduction and internal fixation of these fractures.