Accuracy of Implant Positioning in Total Hip Arthroplasty via a Supine Direct Anterior Approach Using Fluoroscopy

Background: Adequate implantation is important to avoid complications following total hip arthroplasty (THA). This study aimed to evaluate the accuracy and precision of implant placement in the direct anterior approach (DAA) using fluoroscopy in comparison with the anterolateral approach in lateral decubitus position (OCM) using a single implant. Methods: We retrospectively compared propensity score-matched THAs in DAA with fluoroscopy and in OCM. The achievement ratio of the Lewinnek cup safe zone, absolute difference in alignment, and positioning from preoperative planning was evaluated and compared between each approach. Results: 33 patients in both groups were eligible for this study. Significantly more cups were inside the safe zone in the DAA group than in the OCM group (33/33 vs. 25/33, p=0.0048). No significant differences were found between the DAA group and OCM group regarding the discrepancy from the target cup inclination, anteversion, and three-dimensional positioning. No significant difference was noted in stem alignment; however, the equality of coronal alignment variances was smaller in the DAA group (p=0.0047). No significant differences were found in the clinical score and complication rate. Conclusion: The DAA using fluoroscopy may provide more accuracy for cup placement and precision for stem placement than OCM.