Treatment of osteonecrosis of the femoral head by drilling and muscle-pedicle bone grafting. Sixty-one patients with 68 osteonecrotic femoral heads, at different stages of development, were treated surgically; their average age was 36 years. Necrosis followed a fracture in 43 hips and traumatic dislocation in three. It was idiopathic in 14, cortisone-induced in seven and associated with gout in one. The operation of multiple drilling, curettage of the necrotic bone and muscle pedicle bone grafting was performed in all. Cheilectomy of the superolateral part of the femoral head and adductor tenotomy were added in cases of advanced necrosis. Of the several types of muscle pedicle used, tensor fasciae latae anteriorly and quadratus femoris posteriorly were preferred. Full weight-bearing was not permitted for five to six months. The follow-up period varied from three to 12 years. Hip pain was regularly relieved and abduction and rotation of the joints were improved. Those with post-traumatic or idiopathic necrosis did better than those with cortisone-induced necrosis. 