Simultaneous vs staged bilateral total knee arthroplasty among Medicare beneficiaries, 2000-2009.

Simultaneous bilateral total knee arthroplasty (TKA) reportedly has higher postoperative complication rates than staged procedures, but little is known about recent trends and outcomes among Medicare patients. In a 5% national sample of Medicare beneficiaries older than 65 years, we identified 83,441 patients who underwent elective TKA between 2000 and 2009 and compared patients undergoing simultaneous bilateral TKA (n=4519) to staged TKA (n=3788). Use of simultaneous TKA did not change over time (3 in 10,000), but use of staged TKA increased three-fold from 1.4 to 4.4 in 10,000 person-years. We assessed length of stay; 5-year risk of revision; periprocedural (i.e., 90-day) risk of infection; hospitalization for venous thromboembolism (VTE) and myocardial infarction (MI); and death using Kaplan-Meier methods. Simultaneous TKA had higher 90-day risk of death (0.7% vs. 0.3%, P=0.02), VTE (0.9% vs. 0.5%, P=0.07), and MI (0.5% vs. 0.2%, P=0.02). Infection and revision rates were similar between the two groups.