Reducing the risk of nerve injury during Bernese periacetabular osteotomy: a cadaveric study.

The modified Smith-Petersen and Kocher-Langenbeck approaches were used to expose the lateral cutaneous nerve of the thigh and the femoral, obturator and sciatic nerves in order to study the risk of injury to these structures during the dissection, osteotomy, and acetabular reorientation stages of a Bernese peri-acetabular osteotomy. Injury of the lateral cutaneous nerve of thigh was less likely to occur if an osteotomy of the anterior superior iliac spine had been carried out before exposing the hip. The obturator nerve was likely to be injured during unprotected osteotomy of the pubis if the far cortex was penetrated by > 5 mm. This could be avoided by inclining the osteotome 45° medially and performing the osteotomy at least 2 cm medial to the iliopectineal eminence. The sciatic nerve could be injured during the first and last stages of the osteotomy if the osteotome perforated the lateral cortex of ischium and the ilio-ischial junction by > 10 mm. The femoral nerve could be stretched or entrapped during osteotomy of the pubis if there was significant rotational or linear displacement of the acetabulum. Anterior or medial displacement of < 2 cm and lateral tilt (retroversion) of < 30° were safe margins. The combination of retroversion and anterior displacement could increase tension on the nerve. Strict observation of anatomical details, proper handling of the osteotomes and careful manipulation of the acetabular fragment reduce the neurological complications of Bernese peri-acetabular osteotomy.

Anterior femoro-acetabular impingement due to acetabular retroversion. Treatment with periacetabular osteotomy.

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