Evaluation of the accuracy of femoral component orientation by the CT-based fluoro-matched navigation system.

Purpose: Accurate orientation of acetabular and femoral components are important during THA. However, no study has assessed the use of the CT-based fluoro-matched navigation system during THA. Therefore, we have evaluated the accuracy of stem orientation by CT-based fluoro-matched navigation.
Methods: The accuracy of stem orientation by CT-based fluoro-matched navigation was assessed by postoperative CT data. Furthermore, we compared the postoperative stem orientation with the intraoperative registration errors.
Results: The average antetorsion error of the stem (navigation records - postoperative CT) was -0.5° ± 5.2°. The stem valgus error was 0.4° ± 2.7°. The accuracy of the navigation record for the orientation of the stem valgus was dependent on the intraoperative registration errors.
Conclusions: The clinical accuracy of CT-based fluoro-matched navigation is adequate for stem alignment orientation, and the intraoperative verification of registration errors is valuable for checking the accuracy of stem orientation by navigation.