Diverging Surgeon Distribution in Primary Versus Revision Arthroplasty: A National Analysis

Total hip (THA) and total knee arthroplasty (TKA) utilization has increased substantially over the past decade, highlighting the importance of understanding how operative volume is distributed among surgeons. While prior studies have focused on consolidation at the health-system level, surgeon-level procedural concentration remains incompletely characterized.

A retrospective analysis of Medicare fee-for-service claims from 2013 to 2023 was performed using a national Medicare administrative claims dataset. The primary and revision THAs and TKAs were identified using Current Procedural Terminology codes, including surgeons performing ≥ 11 procedures annually. Surgeon-level case concentration was assessed using the Herfindahl-Hirschman Index (HHI), with state-level variation evaluated using change in HHI (2023 to 2013). Entrant surgeons were defined as those who had no cases in the prior two years. Temporal trends were assessed using linear regressions.

Primary THA volume increased from 166,730 to 274,801 and TKA from 390,710 to 526,893 between 2013 and 2023, with corresponding increases in median annual surgeon volume (THA: 21 to 26; TKA: 27 to 31). Surgeon-level HHI declined for primary THA (2.7 to 2.0; β = -0.064/year, P < 0.001) and TKA (1.7 to 1.5; β = -0.016/year, P = 0.022), indicating decentralization. Revision THA volume decreased (5,667 to 1,814) with increasing HHI (42.4 to 132.8; β = +8.37/year, P < 0.001), while revision TKA remained persistently concentrated. Entrant surgeons accounted for 12 to 18% of annual primary arthroplasty volume.

The primary THAs and TKAs have become increasingly dispersed over the last decade, whereas revision arthroplasty remained concentrated among specialist high-volume surgeons, indicating contrasting workforce patterns.