Accurate Leg Length Measurement in Total Hip Arthroplasty: A Comparison of Computer Navigation and a Simple Manual Measurement Device

The measurement of leg length discrepancy (LLD) is important in planning a successful total hip arthroplasty (THA). Many clinical and radiological methods with varying degrees of accuracy have been proposed to carry out this measurement. Intraoperative techniques to as-sess LLD and femoral offset restoration include devices that vary from a Steinmann pin or K-wire, bent to act as a marker or caliper, to specific proprietary devices.1-4) We also have used a simple manual measurement device, the Background: Several studies have shown that better placement of the acetabular cup and femoral stem can be achieved in total hip arthroplasty (THA) by using the computer navigation system rather than the free-hand alignment methods. However, there have been no comparisons of the relevant clinical advantages in using the computer navigation as opposed to the manual intra-operative measurement devices. The purpose of this study is to determine whether the use of computer navigation can improve postoperative leg length discrepancy (LLD) compared to the use of the measurement device. Methods: We performed a retrospective study comparing 30 computer-assisted THAs with 40 THAs performed using a simpl