Improving Acetabular Component Positioning in Total Hip Arthroplasty: A Cadaveric Study of an Inertial Navigation Tool and a Novel Registration Method.

Background: Incorrect acetabular component positioning in total hip arthroplasty (THA) has been associated with poor outcomes. Computer-assisted hip arthroplasty increases accuracy and consistency of cup positioning compared to conventional methods. Traditional navigation units have been associated with problems such as bulkiness of equipment and reproducibility of anatomical landmarks, particularly in obese patients or the lateral position. Purpose: We sought to evaluate the accuracy of a novel miniature inertial measurement system, the Navbit Sprint navigation device (Navbit, Sydney, Australia), to navigate acetabular component positioning in both the supine and lateral decubitus positions. We also aimed to validate a new method of patient registration that does not require acquisition of anatomical landmarks for navigation. Methods: We performed THA in a cadaveric study in supine and lateral positions using Navbit navigation to record cup position and compared mean scores from 3 Navbit devices for each cup position on post-implantation CT scans. Results: A total of 11 cups (5 supine and 6 lateral) were available for comparison. A difference of 2.34° in the supine direct anterior approach when assessing acetabular version was deemed to be statistically but not clinically significant. There was no statistically significant difference between CT and navigation measurements of cup position in the lateral position. Conclusion: This cadaveric study suggests that a novel inertial-based navigation tool is accurate for cup positioning in THA in the supine and lateral positions. Furthermore, it validates a novel registration method that does not require the identification of anatomical landmarks.

Novel Measure of Acetabular Cup Inclination and Anteversion During Total Hip Arthroplasty.

PURPOSE: The purposes of the present research were to assess the accuracy and usability of the inertial navigation system (INS). MATERIALS AND METHODS: The accuracy of the device navigation subsystem was assessed using benchtop testing. The usability was assessed through simulated use with surgeons. These results were compared to recent cadaveric results for the same system. RESULTS: The navigation subsystem had an overall mean absolute error of 1.21° and a maximum absolute error across all devices of 4.79°. The device was found to be usable and to add an estimated 7 minutes to surgery time. CONCLUSION: The INS uses a novel approach to provide the surgeon with accurate and fast acetabular cup inclination and anteversion angles during THA.