Comparing Facility Costs, Patient-Reported Outcome Measures, and Revision Rates in Cementless and Cemented Primary Total Knee Arthroplasty: Findings From a Propensity Score-Matched Patient-Level Value Analysis of 380 Procedures With a Mean 4.3-Year Follow-Up.

Abstract

Health care value accounts for clinical outcomes and cost. A methodology for more accurate cost accounting is time-driven activity-based costing. No prior study has evaluated the value of cementless total knee arthroplasty (TKA) using time-driven activity-based costing. We performed a retrospective propensity score-matched analysis of 76 cementless TKAs and 304 cemented TKAs with a mean follow-up of 4.3 years (range, 1.7 to 8.5). Reference pricing for implants was used, and cementless implants were available at a premium price relative to reference pricing. Value was the primary outcome and was defined twofold: Absolute Value _KOOS-PS was the quotient of 1-year Knee Osteoarthritis Outcome Score-Physical Function Short-Form (KOOS-PS) and facility cost; Incremental Value _KOOS-PS was the quotient of delta KOOS-PS and facility cost. Revision rate was also compared but not factored into our value equation. Cementless TKAs had significantly higher total facility costs than cemented TKAs (971 versus 800 cost units; percent difference: +21.4%; P < 0.001). The cost difference was principally related to cementless TKAs having higher implant costs (542 versus 367 cost units; percent difference: +47.7%; P < 0.001). There were no significant differences in KOOS-PS scores. Cementless TKA was found to have significantly reduced mean Absolute Value _KOOS-PS (48.3 versus 58.1; P < 0.001) and Incremental Value _KOOS-PS (16.5 versus 20.3; P = 0.038). The revision rate at the mean 4.3-year follow-up was low and similar (3.9 versus 2.3%; P = 0.42). We compared value (defined as 1-year patient-reported outcome measures relative to facility costs) between cementless and cemented TKA. Cementless TKAs demonstrate lower value at a mean 4.3-year follow-up due to differences in implant cost. Increased value for cementless TKA is ultimately plausible if reductions in revision rates beyond 5-year follow-up are observed or if cementless TKA implants are incorporated in reference pricing matrices to reduce their cost.