Background: The purpose of this study was to evaluate the interval between the first and second operations for staged total knee arthroplasties (TKAs) in patients with bilateral knee osteoarthritis. Depending on satisfactory preoperative health status, the patients determined the timing of the second operation. We also analysed correlations between the interval and patient characteristics. Methods: Eighty-six patients with bilateral knee osteoarthritis were analysed. The mean follow-up time from the first TKA was 96. months. The side of the first TKA was chosen by the patients. The timing of the second TKA was determined by the patients, depending on their perceived ability to tolerate the additional pain and limitations to activities of daily living. Results: The median interval between the first and second operations was 12.5. months, with a range of 2 to 113. months. In 43 (50%) patients, the interval was &lt
. 12. months. There was no difference in the interval between females and males (p= 0.861), and no correlation between the interval and body mass index or age. There was weak correlation between the year of the first TKA and the interval (R= - 0.251, p= 0.020), with the interval getting significantly shorter as the years progressed (p= 0.032). Conclusions: The median interval between the first and second operations in patients who underwent staged TKAs for bilateral knee osteoarthritis was about 1. year. The results of the current study may help patients and physicians to plan effective treatment strategies for staged TKAs. Levels of evidence: Level II. © 2013 Elsevier B.V.