Safe zone for the superior gluteal nerve in the transgluteal approach to the dysplastic hip: Intraoperative evaluation using a nerve stimulator

Background The superior gluteal nerve can be damaged during the transgluteal approach to the hip in total hip arthroplasty. Methods We studied 30 patients with hip dysplasia who underwent total hip arthroplasty through the transgluteal approach. The course of the inferior branch of the superior gluteal nerve was identified using a nerve stimulator. The distance between the nerve and the tip of the greater trochanter was measured. Results The mean distance was 37 (25-45) mm at the anterior third, 40 (30-50) mm at the middle third, and 44 (35-55) mm at the posterior third of the gluteus medius. The distance was influenced by the severity of hip dysplasia and decreased as the degree of hip dysplasia became more severe. Interpretation A 3-cm safe zone is appropriate in most dysplastic hips. In severely dysplastic hips, however, the superior gluteal nerve occasionally coursed within 3 cm of the tip of the greater trochanter. In such hips, a nerve stimulator can be used to identify the nerve.