Limb length restoration during total hip arthroplasty: use of a caliper to control femoral component insertion and accurate acetabular placement relative to the transverse acetabular ligament.

Abstract

Current methods for restoring or preserving limb length following total hip arthroplasty largely depend on restoring the distance between a fixed point on the pelvis and femur. Each of these techniques allows length correction to be made by combining the effects of both acetabular and femoral height into a single measurement. These methods help to minimise inequality but are anatomically flawed, as they do not allow independent control of placement of the femoral and acetabular components which both contribute to leg length. To address this we present and evaluate a technique that uses a caliper to control the vertical placement of the femoral component and the transverse acetabular ligament to control the vertical height of the acetabular component. Limb lengths were measured in 200 patients who had undergone primary total hip arthroplasty using this technique. Using this method 94% had a postoperative limb length inequality that was 6mm or less (average, +0.38 mm). The maximum measured limb length inequality was +/-8 mm.