Clinical and Nonclinical Determinants of Simultaneous vs Staged Bilateral Total Knee Arthroplasty

Patients requiring bilateral total knee arthroplasty (TKA) may undergo surgery either simultaneously or in a staged fashion. Contemporary trends in utilization, as well as clinical and nonclinical factors correlating with surgical selection, remain undefined.

Adult patients who underwent simultaneous or staged bilateral TKA between 2016 and 2021 were identified. Patient characteristics were assessed, including clinical (age, sex, Elixhauser Comorbidity Index) and nonclinical factors (geographic region, insurance status, and social determinants of health). Multivariate logistic regression was performed to identify predictors of undergoing simultaneous bilateral TKA vs staged bilateral TKA.

Of the 138,468 patients undergoing bilateral TKA, 20,473 (14.8%) had simultaneous and 117,995 (85.2%) had staged bilateral TKA. The proportion of simultaneous procedures declined from 19.0% in 2016 to 7.1% in 2021. Simultaneous TKA patients were younger (63.9 ± 8.3 years vs 65.6 ± 8.6 years for staged; P < .001) and had a lower Elixhauser Comorbidity Index (4.5 ± 3.0 vs 4.9 ± 3.2 for staged; P < .001) than those undergoing staged bilateral TKA. Patients in the Northeast had the highest odds of simultaneous bilateral TKA (relative to Midwest: South odds ratio [OR]: 1.06; West OR: 1.09; Northeast OR: 1.87) (P < .05), while patients with Medicaid (relative to commercial insurance: OR: 0.62), and those with social (OR: 0.78) and economic (OR: 0.93) constraints had lower odds of simultaneous bilateral TKA (all P < .05).

The use of simultaneous bilateral TKA substantially declined between 2016 and 2021 relative to staged procedures. Surgical decisions were associated with both clinical (age, comorbidity burden, sex) and nonclinical (region, insurance, social determinants of health) factors.