Is the tip of the greater trochanter a reliable reference for the rotation centre of the femoral head in total hip arthroplasty ?

A variety of techniques have been used to determine intra-operative leg length during total hip arthroplasty. One method often described is using the tip of greater trochanter as the reference for the rotation centre of the femoral head to align the femoral component. There is little in the literature to support this method of leg length restoration. We analysed standard anterior-posterior pelvic radiographs of 225 patients with osteoarthritis of the hip who were about to undergo total hip arthroplasty. The distance between the tip of the greater trochanter and the rotation centre of the femoral head was measured for the affected hip. The average location of the tip of greater trochanter is 3.4 mm proximal to the centre of the femoral head, with a range from 20 mm proximal to 10 nun distal to the femoral head centre. There is considerable variation in the anatomy of the proximal femur; however, with adequate pre-operative templating, the greater trochanter can be a helpful guide to determine the rotation centre of the femoral head of the femoral component and should be used with other conventional techniques to determine leg length intra-operatively.