Infrared stereo camera matching portable navigation reproduces accurate acetabular cup placement during total hip arthroplasty: A matched cohort study

Background: Positioning of the acetabular cup during total hip arthroplasty (THA) is important for early and long-term outcomes; however, accurate cup positioning is difficult even for experienced surgeons. This study compared the accuracy of an infrared stereo camera-matching portable navigation system for cup positioning during THA in the lateral decubitus position. Methods This retrospective cohort study analyzed data from 104 THA patients who underwent surgery using either infrared stereo camera-matching portable navigation (n = 40) or non-navigation control (n = 64). Patients underwent THA via the anterolateral approach in the lateral decubitus position using a portable navigation system. Patient characteristics including age, body mass index, sex, treated side, target inclination, and target anteversion were adjusted by propensity score matching. Subsequently, we assessed navigation records for intraoperative cup angles, postoperative cup angles measured on CT images, cup angle measurement errors, and other clinical parameters. Results The mean absolute difference in radiographic anteversion between patients with use of navigation and non-navigation was smaller after propensity score matching (3.4 ± 3.1° vs. 5.6 ± 3.0°, p = 0.047). Navigation error (absolute difference in anteversion between postoperative CT and navigation records of > 5°) was significantly associated with posterior pelvic tilt in the navigation group (OR, 1.27; p = 0.030, 95% CI, 1.02–1.57). Conclusions Infrared stereo camera matching portable navigation provides clinically comparable precision and accuracy to determine the orientation of cup placement compared to non-navigation during THA in the lateral decubitus position. Clinicians should consider the use of this navigation system in patients with posterior pelvic tilt during THA.