Intraoperative electromyographic monitoring during periacetabular osteotomy

Periacetabular osteotomy has become the procedure of choice in many centers for the treatment of symptomatic hip dysplasia. Intraoperative real-time nerve monitoring has been advocated during acetabular fracture repair and complex total hip arthroplasties to prevent iatrogenic sciatic nerve injury. To the authors' knowledge there is no information concerning the use of intraoperative electromyographic monitoring during periacetabular osteotomy. The purpose of the current study was to investigate the use of intraoperative continuous electromyographic monitoring during periacetabular osteotomy in a relatively large consecutive series of patients as a mechanism to prevent nerve injury during surgery and as a prognostic indicator of neurologic function after periacetabular osteotomy. From September 1992 to July 1999, 140 consecutive periacetabular osteotomies were done in 127 patients at the authors' institution. There were 96 females and 31 males, with an average age of 32 years at the time of surgery. All patients had intraoperative electromyographic monitoring of femoral and sciatic innervated muscles. All patients were followed up for a minimum of 1 year, until complete resolution of neurologic deficits, or both. Thirty-six patients (26%) had abnormal electromyographic activity recorded during surgery. Seven patients (5%) had peroneal nerve deficits postoperatively including extensor hallucis longus and tibialis anterior weakness with loss of sensation in the first web space. Abnormal electromyographic activity was observed intraoperatively in five of the seven patients with postoperative deficits. Six of the seven injuries resolved completely. One patient with intraoperative electromyographic activity (0.7%) had a postoperative foot drop that persisted for greater than 1 year. There were no femoral, tibial, or obturator nerve deficits observed. Electromyographic monitoring appears to provide prediction of postoperative neurologic deficit.