Background: This study was performed to evaluate whether symptomatic anterior femoro-acetabular impingement due to acetabular retroversion can be treated effectively with a periacetabular osteotomy.

Methods: The diagnosis of femoro-acetabular impingement was based on clinical symptoms, a positive anterior impingement test, and findings of acetabular rim lesions on magnetic resonance imaging. The radiographic diagnosis of acetabular retroversion was based on the cross-over and posterior wall signs. Twenty-nine hips in twenty-two patients (average age, twenty-three years) underwent a periacetabular osteotomy. An arthrotomy was performed in twenty-six hips in order to visualize intra-articular lesions and, in selected cases, to improve a low femoral head-neck offset. The range of motion of the hip was measured, clinical evaluation was performed with use of the score described by Merle d'Aubigné and Postel, and the anterior center-edge angle of Lequesne and de Sèze was measured on radiographs preoperatively and at the time of the latest follow-up.

Results: The duration of follow-up averaged thirty months (range, twenty-four to forty-nine months). The anterior center-edge angle of Lequesne and de Sèze decreased significantly from a preoperative average of 36 degrees (range, 26 degrees to 52 degrees ) to a postoperative average of 28 degrees (range, 16 degrees to 46 degrees ) (p = 0.002). There was a significant increase in the average range of internal rotation (10 degrees, p = 0.006), flexion (7 degrees, p = 0.014), and adduction (8 degrees, p = 0.017). The average Merle d'Aubigné score increased from 14.0 points (range, 12 to 16 points) preoperatively to 16.9 points (range, 15 to 18 points) postoperatively (p < 0.001), and the result was good or excellent for twenty-six hips. Three hips underwent subsequent surgery: one, because of early postoperative loss of reduction; one, for correction of posteroinferior impingement; and one, because of recurrent signs of anterior impingement.

Conclusion: Periacetabular osteotomy is an effective way to reorient the acetabulum in young adults with symptomatic anterior femoro-acetabular impingement due to acetabular retroversion