Leg length inequality in total hip replacement.

Clinical and radiographic leg length inequality and pelvic tilt were measured in the erect posture in 36 patients before and after total hip replacement. Good correlation was observed between clinical and radiographic evaluations of pelvic tilt, assessed as height difference between iliac crests. Intraoperative alteration of leg length correlated well with changes in pelvic tilt but not with changes in true radiographic leg length inequality. It is suggested that adjustment of leg length during total hip arthroplasty should aim at correction of preoperative pelvic tilt observed during clinical and radiographic examination. True leg length, assessed as the height of the vertex of the femoral or prosthetic head is misleading. It does not reveal functional leg length, which is determined not only by the true leg length but also by the position of the hip joint on the pelvic wall.