What Are the Risks and Benefits of Simultaneous Bilateral TKA?

    Dr. Stefano Bini answers ICJR’s questions about simultaneous versus staged bilateral total knee arthroplasty in his practice, including his contraindications and what he tells patients to expect.

    ICJR: When a patient needs both knees replaced, do you perform the procedures simultaneously or do you stage them? If they’re staged, how long between procedures?

    Stefano A. Bini, MD: The operative word in this question is “need.” If both knees are painful and meet the criteria for knee replacement, I will offer bilateral, same-day total knee arthroplasty (TKA) or unicompartmental knee arthroplasty. If the patient choses to stage the knees, my recommendation is to wait 3 months or more.

    ICJR: What percentage of your TKA patients undergo simultaneous bilateral TKA versus staged bilateral TKA?

    Dr. Bini: I do not have hard data on this question because those who undergo staged TKA may not have been candidates for bilateral surgery when they presented. In the literature, my prior research, and my practice, the incidence of a patient requiring a second knee if their first one was replaced is about 20%.

    ICJR: What are your indications for simultaneous versus staged bilateral TKA? What are your contraindications?

    Dr. Bini: A history of coronary artery disease (or a personal preference for staging the procedure; more on that later) or an ASA score more than 2 are the only contraindications to bilateral surgery if the patient has bilateral pathology. Any patient with bilateral disease in which each knee is independently indicated for a TKA would be a candidate, except as noted above.

    My work and that of others using large databases with sufficiently granular information to identify rare complications has shown that in patients undergoing modern arthroplasty – defined as rapid rehabilitation protocols with early discharge from the hospital – simultaneous versus staged procedures have the same risk of major complications. [1-3] The key, again, is a cardiac history.

    Sadly, the idea that bilateral surgery is riskier, based on data from older studies when the practice of arthroplasty was fundamentally different, is still prevalent.

    ICJR: Do you offer simultaneous bilateral TKA to patients or do they have to bring it up? What do you tell them about risks and benefits?

    Dr. Bini: Not many patients or caregivers know that same-day surgery for bilateral knee replacement is an option. So, if both knees are candidates for TKA, I will bring it up.

    My reading of the modern literature on the topic is pretty clear: The cumulative risks are equivalent for staged versus simultaneous bilateral knee replacement in non-cardiac patients. [1-3] In shared decision-making models, this information should be provided to patients objectively and not presented in a biased manner. For example, informing a patient that the risk of something doubles from a given option is not the same as also telling them that the risk in question goes from 0.5% to 1%.

    If that is done, in my experience, the decision to do same-day bilateral surgery almost never hinges on the question of risk. Most patients make the decision based on concerns over pain and rehabilitation. Patients with many stairs at home, who are alone, have poor social support, are older, or are poor ambulators at baseline tend to be conservative in their approach to surgery. The same can be said of patients who have difficulty managing pain.

    Patients who are busy, younger, working individuals who cannot easily take time off work, have support at home, and have the necessary resources to help them through recovery tend to favor simultaneous surgery. Knees heal in series and not in parallel, thus the idea of being “done” with bilateral surgery in the same time frame as one knee is appealing to these patients, even if the up-front “costs” are higher.

    Thus, from the patient’s perspective, the question does not hinge on relatively minor changes in clinical risks, such as the risk of infection, pulmonary embolism, or wound healing complications. Instead, the decision for most patients is made based on the perception and fear of pain and the realities of their social environment.

    ICJR: What outcomes have you observed in patients undergoing simultaneous bilateral TKA?

    Dr. Bini: In my unilateral TKA practice, I will see patients at 1 month and then at 1 year after surgery. Patients who undergo bilateral surgery have an additional follow-up visit at 3 months after surgery. By then, they are generally doing great and are happy that they do not need to go through another surgery.

    I tell bilateral candidates at our first visit that they will generally like one knee better than the other and that I do not know which one it will be. Preference does not seem to corelate with the preoperative extent of disease. By 1 year, that variance seems to abate, but one knee is generally slightly happier than the other despite an identical approach to TKA with the same implants. It’s always a good idea to set expectations up front.

    Author Information

    Stefano A Bini, MD, is Professor of Orthopaedic Surgery at University of California San Francisco, San Francisco, California.

    Disclosures: Dr Bini has disclosed that he is a consultant for Stryker and Johnson & Johnson and that he has received research support from Zimmer Biomet.


    1. Bini, S. A., Khatod, M., Inacio, M. C., & Paxton, E. W. (2014). Same-day versus staged bilateral total knee arthroplasty poses no increase in complications in 6672 primary procedures. The Journal of arthroplasty29(4), 694-697.
    2. Vail, T., Tsay, E., Grace, T. R., Roberts, H., & Ward, D. (2018, October). Bilateral simultaneous versus staged total knee arthroplasty: minimal difference in perioperative risks. In Orthopaedic Proceedings (Vol. 100, No. SUPP_12, pp. 32-32). The British Editorial Society of Bone & Joint Surgery.
    3. Mutsuzaki, H., Watanabe, A., Komatsuzaki, T., Kinugasa, T., & Ikeda, K. (2018). Investigation of perioperative safety and clinical results of one-stage bilateral total knee arthroplasty in selected low-risk patients. Journal of orthopaedic surgery and research13(1), 14.