Do Surgeon Volume and Surgeon Experience Correlate with Patient-Reported Outcomes or Costs of Care in Unicompartmental Knee Arthroplasty?

Abstract

Surgeon volume and experience may impact patient-reported outcome measures (PROMs) and costs in total knee arthroplasty. However, whether the same relationship exists in unicompartmental knee arthroplasty (UKA) is unclear. We investigated whether surgeon volume and experience drove variations in PROMs or Time-Driven Activity-Based Costing (TDABC) in UKA. We sourced data from a prospectively maintained multi-institutional arthroplasty registry. Patients completed the Knee Injury and Osteoarthritis Outcome Score - Physical Function Short-form (KOOS-PS) with thresholds for minimal clinically important difference (MCID) and patient acceptable symptom state (PASS). A stratum-specific likelihood ratio (SSLR) analysis was used to categorize surgeons into volume and experience levels: low-volume (annual volume less than 16); mid-volume (annual volume 16 to 40); high-volume (annual volume greater than 40). The SSLR analysis did not identify meaningful thresholds for surgeon experience. Because not all registry centers perform TDABC, our PROM analysis investigated 794 UKAs performed by 32 surgeons, while our TDABC sub-analysis investigated 416 UKAs performed by 12 surgeons. Chi-square tests and one-way analyses of variance compared MCID, PASS, and costs between groups. Low-volume UKA surgeons were associated with prolonged operating room times (low-volume: 110 versus high-volume: 73 minutes; P < 0.001) and lengths of stay (low-volume: 1.2 versus high-volume: 0.6 days; P < 0.001). Both MCID and PASS achievements were similar across volume levels (P = 0.80 and 0.84, respectively). However, low-volume surgeons were associated with increased costs (low-volume: 744 versus mid-volume: 662 and high-volume: 662 cost units (CUs); P < 0.001). Low-volume UKA surgeons had increased costs. However, MCID and PASS achievements were similar for UKA surgeons of all volume levels. There were no meaningful thresholds for surgeon experience. These results may reassure surgeons of all experience levels to pursue UKAs, while remaining aware of the positive influence of volume on cost-effectiveness.