Osteotomy of the greater trochanter continues to be an important surgical technique, especially in revision and difficult primary hip replacement, which implied the tightness of abductors.

We advocate the frog-leg lateral radiograph to determine the reducibility of the dislocation at the level of true acetabulum in order to identify the sufficient length of abductors while sitting. This flexibility of soft tissue structure composed of abductor is compromised once hip is reduced, because of difficulty in bringing the trochanter down to its bed.

In practice, transtrochanteric approach and shortening of proximal femur were applied and greater trochanter was transferred distally for restoring of abductors power(modified osteotomy), while reducing the possibility of trochanteric dislodgement. In fact, the wire force is reduced by 25 % while the bone union compressive force is unchanged in the modified osteotomy compared with conventional osteotomy. We evaluated 17patients(23 hips) in DDH and 15 patients in tuberculous hip. Conventional osteotomy was performed in tuberculous hip and modified osteotomy in DDH.

Nonunion of osteotomized trochanter was found in the case of 5 tuberculous hips especially irreducible in the frog-leg lateral radiograph preoperatively.