Acetabular retroversion in post slipped capital femoral epiphysis deformity.

PURPOSE: While the femoral deformity in post slipped capital femoral epiphysis (SCFE) hips has been implicated in the development of femoral acetabular impingement, little has been studied about the acetabular side. The purpose of our study was to determine the frequency of morphologic changes suggestive of acetabular retroversion in patients who have sustained a SCFE.

METHODS: IRB approval was obtained and the records of patients from 1975 to 2010 were searched for ICD-9 codes for SCFE. A total of 188 patients were identified for the study. Two observers evaluated AP radiographs for evidence of acetabular retroversion as characterized by the presence of either an ischial spine sign or a crossover sign. Demographic data, date of onset, and treatment were recorded. For analysis, the right hip was used in patients with bilateral involvement.

RESULTS: Of the 188 patients identified, 5 patients had an incorrect diagnosis and 41 patients had missing or inadequate films, leaving 142 patients (284 hips) for review. 57 patients (114 hips) had bilateral SCFE and 85 patients had unilateral SCFE. 79 % (n = 45) of the right hips with bilateral SCFE and 82 % (n = 70) of the unilateral involved hips had at least one sign of retroversion. Uninvolved hips had at least one sign of retroversion 76 % (n = 65) of the time.

CONCLUSIONS: When compared to previously published values for normal patients, patients with SCFE appear to have an increased incidence of acetabular retroversion.