Determining the learning curve for anterolateral supine total hip arthroplasty: a retrospective analysis of six hundred and forty consecutive cases performed by a single surgeon.

Abstract

Purpose: To characterize the learning curve for single-surgeon performed anterolateral supine (ALS)-total hip arthroplasty (THA).

Methods: We analysed 640 consecutive primary ALS-THAs performed between April 2017 and August 2024, including procedures performed with supervised assistance during 2017-2019. Operative time (OT), blood loss (BL), and complication rate (CR) were evaluated. Temporal trends in OT and BL were assessed using cumulative sum (CUSUM) analysis, and a data-driven single change-point analysis was performed for CR using 100,000 Monte Carlo permutations. Firth's penalised logistic regression assessed the association between continuous case numbers and complications after adjustment for age, sex, and American Society of Anesthesiologists (ASA) physical status.

Results: OT and BL CUSUM curves peaked at cases 411 and 437, respectively. Mean OT decreased from 74.8 to 66.3 min and BL from 251.6 to 184.6 mL between 2022-2023 (both Holm-adjusted P < 0.001). Nine cases (1.4%) experienced 11 complication events. The estimated CR change point was case 281, with pre- and post-point CRs of 2.8% and 0.3%, respectively, but the permutation test was not significant (P = 0.1021). Increasing experience was associated with lower early complication odds after adjustment (odds ratio 0.64 per 100-case increase, 95% confidence interval 0.40-0.94; P = 0.023).

Conclusion: The ALS-THA learning curve varied by outcome, with operative efficiency improving after approximately 400 procedures. Increasing experience was associated with lower odds of early complications, supporting outcome-specific rather than single-threshold assessment.