Comparison of accuracy between Navbit Sprint and AR-CT-based navigation in total hip arthroplasty

A portable navigation system that constructs a three-dimensional coordinate system by laterally tilting the operating table without anterior superior iliac spine registration has been introduced for total hip arthroplasty (THA). This study compared the accuracy of intraoperative navigation values in THA between a novel portable navigation system and an augmented reality (AR)-computed tomography (CT)-based navigation system. Thirty-four primary cementless THAs were retrospectively analyzed. All procedures were performed using an anterolateral approach in the supine position. Using AR-CT-based navigation, coronal pelvic tilt was adjusted to 0°, and sagittal and axial tilts were recorded. Table tilting was then performed to complete portable navigation registration. Acetabular cups were implanted using AR-CT-based navigation, and intraoperative measurements were obtained using the portable system. Postoperative CT measured radiographic inclination (RI) and anteversion (RA). Navigation error was defined as the absolute difference between intraoperative measurements and postoperative CT values. The association between portable navigation error and pelvic tilt at registration was also examined. Mean postoperative RI and RA were 39.3° ± 3.1° and 15.4° ± 3.1°, respectively, with all components within the Lewinnek safe zone. Mean navigation errors for AR-CT-based navigation were 1.9° ± 1.2° (inclination) and 1.9° ± 1.4° (anteversion). Portable navigation showed higher errors: 2.6° ± 2.7° (inclination) and 4.3° ± 2.9° (anteversion). Anteversion error was significantly greater with portable navigation and positively correlated with axial pelvic tilt at registration. Portable navigation showed lower anteversion accuracy than AR-CT-based navigation. Axial pelvic tilt at registration may affect anteversion accuracy with portable navigation.