Controversy still exists regarding the efficacy and safety of performing bilateral total knee replacements under a single anesthetic versus performing them under separate anesthetics separated by some arbitrary period of time. Some studies suggest that the bilateral procedure is safe while others show a disproportionately high risk of complications when both knees are replaced at the same surgery.
In order to shed more light on the subject, a literature search was performed looking at all studies published in the English literature over the past 10 years addressing the efficacy and safety of simultaneous (2 surgeons operating at the same time, 1 on each knee) or sequential (1 surgeon operating on 1 knee, then directly on the other knee under the same anesthetic) compared to staged total knee replacements (2 knees replaced, each under a separate anesthetic separated by some arbitrary period of time between the two).
Although some literature suggests that bilateral total knee replacements under a single anesthetic is safe, particularly in young, healthy patients, the preponderance of the literature casts some doubt on the safety of the bilateral procedure, particularly if the patient is elderly or has any pre-existing health issues, most notably cardiac, pulmonary, or neurological problems.
Given the body of literature available, it is my opinion that except in rare circumstances, it is in most patients’ best interest to perform bilateral total knee replacements in a staged fashion. The minimum time between procedures has not been well established. Some studies suggest 4-7 days is adequate while others suggest waiting 3-4 months. I typically suggest waiting a minimum of 4-6 weeks, although there is not much science yet to support this somewhat arbitrary number.