Development of a non-invasive augmented reality-based navigation system for total hip arthroplasty in the supine position

Abstract Background A new non-invasive augmented reality (AR)-based portable navigation system was developed for accurate cup positioning during total hip arthroplasty (THA) in the supine position. This study aimed to clarify whether the navigation system supports cup positioning more accurately than a conventional goniometer during surgery. The navigation system may provide more accurate cup alignment than the conventional goniometer. Methods Sixty patients who underwent THA in the supine position were enrolled. The navigation system was used for 30 patients (navigation group), and a conventional goniometer was used for 30 patients (control group) to measure radiographic cup inclination and anteversion during surgery. The primary outcome was the absolute value of the difference in cup alignment measured during surgery and by postoperative radiography. Results The new non-invasive AR-based navigation system showed superior cup positioning accuracy compared to a conventional goniometer. An assessment of the primary outcome showed no significant difference in the radiographic cup inclination in the navigation and control groups (2.9° vs. 3.2°; mean difference, 0.3°; 95% confidence interval, -1.4–0.9; p = 0.67); however, the positioning in the navigation group was significantly more accurate than that in the control group in terms of radiographic anteversion (3.4° vs. 5.4°; mean difference, 2.0°; 95% confidence interval, 0.4–3.8; p = 0.017). Conclusions A new non-invasive AR-based portable navigation system resulted in more accurate cup positioning than the conventional goniometer. Because it is non-invasive, this system should be used for THA in the supine position.