BackgroundBilateral total knee arthroplasty (TKA) is required for many patients. There are few studies comparing the overall costs of staged and simultaneous bilateral TKA.MethodsThe Taiwan National Health Insurance Research Database (NHIRD) was searched, and the total medical costs of 452 patients who received simultaneous bilateral TKAs were compared with those of 690 who received staged bilateral TKAs.ResultsAll categories of medical costs were lower in the simultaneous TKA group, with the exception of therapeutic procedure fees which were higher in the simultaneous bilateral TKA group. The 10-year prosthesis survival rates for simultaneous and staged bilateral TKA were 90.9% and 87.5% (p > 0.05), respectively.ConclusionsThese results indicate that simultaneous bilateral TKA is more cost effective than staged bilateral TKA. Prosthesis survival is not affected by the choice for staged or simultaneous bilateral TKA.