Intraoperative electromyography of the superior gluteal nerve during lateral approach to the hip for arthroplasty - A prospective study of 12 patients

The purpose of this study was to evaluate the incidence of intraoperative s uperior gluteal nerve irritation and to identify specific surgical maneuver s that may harm the nerve. Continuous intraoperative electromyography (EMG) monitoring of the superior gluteal nerve-innervated muscles (gluteus mediu s and tensor fascia lata muscles) was performed in 12 patients undergoing t otal hip arthroplasty. A modified lateral approach was used, including a pa rtial anterior osteotomy of the greater trochanter with splitting of the gl uteus medius and vastus lateralis muscles. All patients had a clinical foll ow-up examination 1 year postoperatively to evaluate abductor muscle functi on. Irritation of the nerve occurred first during splitting of the gluteus medius muscle, then with increased gluteus medius retraction for exposure o f the acetabulum, and finally during positioning of the leg for preparation of the femur. The detected EMG alterations were important because they wer e found in a single patient with persistent abductor muscle weakness.