Preoperative templating for the equalization of leg lengths in total hip arthroplasty

The method and results of preoperative templating for the re-establishment of leg length equality during total hip replacement (THR) are reported. The method is a modification of the technique of Müller and requires an anteroposterior radiograph of the pelvis that includes the proximal third of both femora, appropriate acetabular and femoral templates, and tracing paper. To obtain equalization of leg lengths and tissue tension, a composite drawing is made of the operative plan, with all component sizes and important measurements clearly marked. During THR, the lesser trochanter is identified and the femoral neck is osteotomized after a direct measurement is made. These principles were followed in a prospective, consecutive series of 42 primary THR procedures performed by one surgeon. All the radiographic measurements were performed by a single observer. The leg length discrepancy on the postoperative radiograph averaged 3mm (standard deviation = 3mm, range: -9 to +9mm). The postoperative clinical leg length discrepancy averaged 0mm (range: -10 to +10mm). None of the patients complained of leg length inequality. Preoperative templating allows different alternatives to be traced on paper prior to the actual surgical procedure. This method also helps determine the requirements for special prosthetic implants. Acceptable results for postoperative leg length equality may be reliably achieved using this method.