Institutional Case Volume as a Determinant of the Operative Efficiency in Robotic-Assisted Total Hip Arthroplasty: Analysis of the American Joint Replacement Registry.

INTRODUCTION: The adoption of robotic-assisted total hip arthroplasty (RA-THA) has grown substantially in recent years, yet the relationship between institutional surgical volume and the operative efficiency remains underexplored. This study aimed to evaluate patterns of RA-THA utilization across U.S. institutions and analyze how surgical volume influences the trajectory toward operative efficiency.

METHODS: Data were obtained from the American Joint Replacement Registry, identifying all primary elective RA-THA cases performed between January 2017 and December 2024. Cases missing operation time, institution identifiers, or fixation data were excluded. Institutions were stratified into low (less than 5), medium (5 to 11), and high (≥ 12) volume groups based on median monthly procedure count. Operation time trends were analyzed using centered linear weighted moving averages (window = 50), with efficiency assessed via cumulative sum (CUSUM) analysis. An efficiency threshold was defined as a median operative time ≤ 90 minutes, based on literature benchmarks. Statistical comparisons were performed using Chi-square tests and appropriate parametric or non-parametric tests.

RESULTS: A total of 46,805 RA-THA cases across 305 institutions were included. Low-volume centers (69.2%) had a mean operative time of 102.8 ± 40.4 minutes, medium-volume centers (20.0%) 90.9 ± 36.0 minutes, and high-volume centers (10.8%) 85.0 ± 48.0 minutes. The CUSUM analysis revealed that high-volume institutions achieved and sustained sub-90-minute operative times after approximately 300 cases, compared to 550 cases for medium-volume centers. Low-volume centers showed modest improvements but failed to maintain times below the efficiency benchmark. Overall, 78.8% of high-volume, 50.8% of medium-volume, and 38.9% of low-volume institutions reached the efficiency target.

CONCLUSION: Robotic-assisted THA efficiency improves with institutional surgical volume. High-volume centers achieve proficiency more quickly and sustain efficient operation times more reliably than lower-volume centers. The institutional operative efficiency substantially exceeds individual surgeon learning curves, requiring hundreds of procedures to achieve consistent efficiency. These findings emphasize the importance of institutional experience in realizing the benefits of robotic technology in hip arthroplasty.