An Evaluation of Precision in Implant Placement During the Early Learning Curve for the Direct Anterior Approach in Total Hip Arthroplasty

Background: Acquiring new skills is associated with a requisite learning curve, with potential for increased complications. While previous studies have evaluated complications associated with the learning curve for the direct anterior approach, no studies have evaluated whether there is a decrease in surgical precision during this formative period. The purpose of our study was to compare the precision of implant placement during a surgeon's early learning curve with the direct anterior (DA) approach for total hip arthroplasty (THA) with that of the surgeon's previous approach. Methods: Between 7/2012 and 3/2021, five surgeons converted from a posterior (PA) or anterolateral (AL) approach to a DA approach for primary THA. For each surgeon, initial cases using the DA approach were compared 1:1 with cases using the PA or AL approach before the transition. Radiographic parameters were recorded for each patient. Statistical analysis was conducted using the Bartlett test (precision) for homogeneity of variances and the F-test for pairwise comparisons of variances across surgical approaches. Results: A total of 618 patients were included. Across all surgeons, the DA approach was more precise with postoperative leg length ( P = 0.003) and femoral offset ( P = 0.009) when compared with the PA approach and more precise with leg length ( P = 0.016) when compared with the AL approach. No loss in precision was observed with the DA approach compared with the PA and AL approaches for acetabular inclination (all P < 0.05). Conclusion: The direct anterior approach demonstrated comparable or improved precision with implant positioning even during a surgeon's early learning curve.