Simultaneous Bilateral Knee Replacement

For patients who have significant arthritis in both knees, the question often comes up "should I have both knees replaced at the same time"?

"Simultaneous" bilateral knee replacement refers to both knees being replaced during one surgery. The other option is "staged" unilateral knee replacement, where the knees are replaced one at a time, usually about three to six months between surgeries.

While the scientific research does not provide a definitive answer, many studies do suggest a higher risk for complications if both knees are replaced during one surgery. For our patients, safety always comes first. If there is a concern that trying to replace both knees with one surgery will put the patient at a greater risk for problems during or after surgery, Dr. Kaper will not accept this risk for his patients.

Several recent studies highlight the concerns associated with replacing both knees at the same time-

The most comprehensive comparison done to date, researchers at the USC Keck School of Medicine analyzed over 21,000 patients who had undergone simultaneous TKA surgery and compared them to over 126,000 patients who underwent unilateral TKA.  The patients having both knees replaced at the same time were noted to have 2x the risk of stroke, pulmonary embolism and acute blood loss.  They were also 8x more likely to need a blood transfusion than if the surgeries were done one at a time.

Published in December of 2020, another set of researchers showed that even among the healthiest patients, that surgical risk increased two to three times for bilateral compared to unilateral knee replacement. (Bilateral Simultaneous Total Knee Arthroplasty May Not Be Safe Even in the Healthiest Patients. Warren et al. The Journal of Bone and Joint Surgery: December 24, 2020).

One other recent study demonstrated that the risk with simultaneous bilateral TKA was increased by 50% for minor complication, 30% for major complication, with a 2 1/2 times higher chance for mortality after surgery. These risks were most concerning in the patients over the age of 65.  (

Needless to say, these statistics do not support the "safety first" approach. Consequently, although Dr. Kaper will consider replacing both knees at the same time for a patient, he is very careful for whom he may recommend this surgery.

If you have specific questions or concerns about your surgical treatment decisions, please do not hesitate to let us know.

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