Abstract
BACKGROUND: 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.
METHODS: 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 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), and high volume (annual volume greater than 40). The stratum-specific likelihood ratio 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 subanalysis investigated 416 UKAs performed by 12 surgeons. Chi-square tests and one-way analyses of variance compared MCID, PASS, and costs between groups.
RESULTS: 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; P < 0.001).
CONCLUSIONS: 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.