A preliminary validation study showing comparable accuracy between Computed Tomography based and imageless portable...

Accurate acetabular cup placement is essential in total hip arthroplasty (THA). We hypothesized that the newly introduced Computed Tomography (CT)-based portable navigation system would demonstrate accuracy comparable to that of the imageless portable navigation system. The aim of this study was to compare cup placement accuracy between the CT-based and imageless portable navigation systems of the same platform in THA performed in the lateral decubitus position.

This retrospective cross-sectional study included 36 patients who underwent primary THA via a direct lateral approach in the lateral decubitus position. In all cases, both imageless and CT-based portable navigation systems were used concurrently. Postoperative cup alignment was evaluated using three-dimensional CT (3D-CT). The primary outcome was the absolute error in cup inclination and anteversion, defined as the difference between intraoperative navigation values and postoperative 3D-CT measurements in the functional. Secondary outcomes included outlier rates and registration success rates.

No statistically significant differences were observed between the imageless and CT-based portable navigation systems in the mean absolute error for inclination (2.2 ± 1.8° vs. 2.3 ± 1.8°, p = 0.93) or anteversion (2.3 ± 2.3° vs. 2.6 ± 2.5°, p = 0.41). There were no significant differences in outlier proportions. The registration success rate was 92% (36/39) due to three technical failures.

In this preliminary study, the CT-based portable navigation system demonstrated cup placement accuracy comparable to that of the imageless portable navigation system. Although the CT-based system may provide additional spatial information intraoperatively, its impact on clinical outcomes remains unclear and requires further longitudinal investigation.