Approach and incision: Under general anesthesia with endotracheal intubation, the operation was performed with the patient in a lateral decubitus position. The Moore approach (posterior incision) is adopted.

Obtain grafting bone pedicled with femoral quadratus, cortical bone strips, and cancellous bone pellets and flakes: Expose the external rotator muscles of hip and carefully separate the upper and lower edges of the femoral quadratus, and cut off the attachment points of obturator and gemellus muscle on the femur. After the posterior intertrochanteric area with the insertion of the femoral quadratus is identified, a rectangular bone block pedicled with the femoral quadratus is obtained using an osteotome. Its length should be 3.5–5.0 cm, width of 1.4–2.0 cm, and thickness of 1.0–2.0 cm (Fig. 16.2a, b). The largest bone block can be used it up to 2.0 × 2.0 × 5.0 cm. In addition, cortical bone strips shaped like matchsticks and cancellous bone in shape of small pellets and flakes are obtained from the greater trochanteric area (Fig. 16.2c).

Thoroughly remove necrotic bone: The posterior part of joint capsule is resected. A fenestration groove in size of 1.4 × 1.4 cm is made below the cartilage edge of the femoral head at the posterior side of the femoral neck (Fig. 16.3a). Through this window, the necrotic bone is thoroughly removed until the inner surface of cartilage by using osteotome, curette, or burr (Fig. 16.3b, c). The necrotic area is usually located in the superior and anterior lateral region in the femoral head and can be seen clearly when performing this posterior approach. Care should be taken not to cut through or scratch and perforate the cartilage layer. The depth of the empty cavity usually measures around 3.5 cm.

Bone grafting: