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.

Background: 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.

Methods: 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 was the quotient of 1-year Knee Osteoarthritis Outcome Score-Physical Function Short-Form (KOOS-PS) and facility cost; Incremental Value was the quotient of delta KOOS-PS and facility cost. Revision rate was also compared but not factored into our value equation.

Results: 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 (48.3 versus 58.1; P < 0.001) and Incremental Value (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).

Conclusions: 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.