Evaluation of the accuracy of computed tomography-based navigation for femoral stem orientation and leg length discrepancy.

Although there is a great deal in the literature about the clinical accuracy of computed tomography (CT)-based navigation systems for acetabular cup orientation and leg length discrepancy in total hip arthroplasty, there is little analysis of femoral stem orientation. Thirty total hip arthroplasties in which CT-based navigation system had been used had their anteversion, valgus angle of stem, and leg length discrepancy measured on postoperative CT data. Differences in postoperative measurements from intraoperative records were -0.6° ± 4.8° (range, -11° to 10°) for stem anteversion, -0.2° ± 1.8° (range, -4° to 3°) for valgus angle of stem, and 1.3 ± 4.1 mm (range, -6 to 10 mm) for leg length. Although this system may need further improvement for stem orientation, it was helpful for intraoperative leg length adjustment.