Comparison of conventional versus computer-navigated acetabular component insertion

This retrospective study compared the efficacy of computer navigation and conventional freehand techniques to place acetabular component orientation in the target position of acetabular cup inclination of 45 degrees and anteversion of 20 degrees. We selected 69 patients who had undergone total hip arthroplasty with freehand cup insertion who had computed tomography (CT) to plan for acetabular cup placement of the contralateral side. This group was compared with 98 patients who underwent CT-based cup insertion, and all had postoperative CT. After CT-based cup placement, average cup position was 43 degrees inclination (95% confidence interval [CI], 0.97; range, 30 degrees-58 degrees) and 22.2 degrees anteversion (95% CI, 1.72; range, 5 degrees-38 degrees). For freehand, average cup position was 45.7 degrees inclination (95% CI, 2.63 degrees; range, 26 degrees-64 degrees) and 28.5 degrees anteversion (95% CI, 3.80 degrees; range, 9 degrees-53 degrees). F ratio was 5.56 for inclination and 3.67 for anteversion ( P < .0001). This study demonstrated substantial statistical improvement in accuracy of cup placement using CT-based navigation compared with freehand methods.