Staged Versus Simultaneous Bilateral Knee Arthroplasty: Does Minimal Cost Difference Justify Risks?

Background: Simultaneous bilateral total knee arthroplasty (BTKA) is associated with a higher risk but can be perceived to afford faster improvement and mitigated costs versus staged BTKA. We aimed to explore (1) health care utilization, (2) surgical supply costs of simultaneous BTKA; and (3) 1-year improvement in patient-reported pain, function, and quality of life (QOL) versus staged BTKA. Methods: A prospective cohort of 198 simultaneous and 625 staged BTKAs was obtained (2016-2020). Simultaneous BTKA cohort was propensity score-matched (1:2) to a similar group of staged patients (simultaneous = 198 versus staged = 396). Outcomes included length of stay, discharge disposition, 90-day readmission, 1-year reoperation, surgical episode supply cost, Knee Injury and Osteoarthritis Outcome Score (KOOS)-pain, KOOS-Physical Function Short Form, and KOOS-QOL. Rates of attaining minimal clinically important difference and Patient Acceptable Symptomatic State were calculated. Results: Compared to both staged BTKA surgeries combined, simultaneous BTKA demonstrated shorter median net length of stay (2.00 [2.00, 3.00] days versus 2.00 [2.00, 4.00] days; P < .001) but higher rates of nonhome discharge (n = 56 [28.3%] versus n = 32 [4.04%]; P < .001), 90-day readmission (n = 20 [10.1%] versus n = 48 [6.06%]; P = .047) and similar reoperation rates (P = .44). Simultaneous BTKA afforded slight reduction in net surgical cost compared to that of both staged BTKAs combined ($643; P = .028). There was no significant difference in 1-year improvement and minimal clinically important difference attainment rates with simultaneous versus staged BTKA for KOOS-pain (P = .137 and P = .99), KOOS-QOL (P = .095 and P = .81), or KOOS-Physical Function Short Form (P = .75 and P = .49, respectively) or Patient Acceptable Symptomatic State (P = .12). Conclusion: Staged BTKA is associated with similar 1-year pain, function, and QOL at a better safety profile and minimal surgical supply cost increase compared to simultaneous BTKA.