Accuracy of acetabular cup insertion in an anterolateral supine approach using an accelerometer-based portable navigation system

The purpose of this study was to determine the accuracy of acetabular cup insertion during total hip arthroplasty (THA) in a supine position using an accelerometer-based portable navigation system. A single-surgeon study was conducted in which 62 prospective patients with navigation and 42 retrospective patients without navigation as historical controls were compared. The patients underwent THA via an anterolateral supine approach. The absolute values of errors of radiographic inclination and anteversion were calculated. The navigation error was also calculated. The factors that affected the absolute values of errors of cup alignment were determined. The mean absolute error of the postoperative CT measurement from the target angle for radiographic inclination was 3.8 degrees in the navigation group and 6.6 degrees in the control group (P < 0.001). The mean absolute error for anteversion was 3.3 degrees in the navigation group and 5.9 degrees in the control group (P < 0.001). The mean absolute values of navigation error were 3.7 degrees +/- 2.8 degrees in inclination and 3.0 degrees +/- 2.6 degrees in anteversion. Changes in the pelvic tilt angle among preoperative, intraoperative, and postoperative were the significant risk factors for the absolute values of navigation error of anteversion relative to the anterior pelvic plane. Other factors affecting the absolute values of errors in the navigation group were not found for radiographic inclination and anteversion. The portable navigation system significantly improved the accuracy of cup inclination and anteversion. Changes in the pelvic tilt were the risk factors for the error of anteversion relative to the anterior pelvic plane.

Automated summary

This study found that the accuracy of acetabular cup insertion during total hip arthroplasty was significantly improved using an accelerometer-based portable navigation system. Changes in pelvic tilt angle were identified as a risk factor for errors in anteversion relative to the anterior pelvic plane.