Bilateral Knee Replacement: Both Knees at Once or Staged?

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Need both knees replaced? Compare same-day and staged bilateral knee replacement — who qualifies, the risks, recovery, and questions to ask your surgeon.

Bilateral Knee Replacement: Both Knees at Once, or One at a Time?

If both of your knees are worn out, the first question usually isn't which implant to choose. It's timing. Bilateral knee replacement can be done in a single surgery, with both knees replaced under the same anesthetic, or in two separate surgeries a few months apart.

Neither route is the right answer for everyone, and the evidence on which one is safer is more mixed than most patients are told.

The two ways to do it

In a simultaneous (same-day) operation, the surgeon replaces both knees in one sitting. That takes roughly three to four hours, compared with about two hours for a single knee, according to the Rothman Institute.

In a staged approach, one knee is replaced first and the second follows later, typically about three months on. Harvard Health's guidance, reviewed by a Massachusetts General Hospital orthopedic surgeon, suggests waiting at least three months between the two, by which point most recovery from the first knee is complete and the strength and coordination of that leg have returned.

If one knee is clearly worse, it normally goes first.

What the research actually says

Here's the honest picture: recent meta-analyses don't agree with each other.

A 2025 systematic review and meta-analysis concluded that replacing both knees at once lowers the chance of reoperation and cost, at the expense of higher complications and mortality. A Journal of Arthroplasty meta-analysis likewise linked one-sitting surgery with a shorter hospital stay but higher mortality. A third review, on the other hand, associated simultaneous surgery with lower infection, cost, and readmission rates.

That's a sign the answer depends on who is being operated on. Surgeons generally offer one-sitting surgery only to healthier patients, which is likely part of why a fair comparison is hard to make, and why averages across all patients can hide what happens for a well-chosen individual.

What the sources do agree on is more useful. Harvard Health notes that when both knees are done together there is a slightly higher risk of a major complication, such as a blood clot or heart attack, though the overall risk stays low. Longer surgery also means longer anesthesia, which can add risk. And when patients are well selected, long-term results for pain, function, and range of motion look similar either way.

Bilateral knee replacement: who is a candidate for both knees at once?

This is where the decision is really made. Based on the Harvard Health and Rothman guidance, surgeons typically look for:

Good general health, with no significant heart or lung disease. A body weight that isn't severely high. Reliable help at home during the first weeks. And, for some people, a genuine need to limit time away from work or family responsibilities.

Age is where the two sources differ, which tells you something in itself. Harvard Health generally describes simultaneous surgery for people under about 75, while Rothman describes candidates as typically 60 or older and notes that complication risk is higher in men and in older patients. There is no single age cut-off. It's a judgment your surgeon makes about your overall fitness, not a number on a chart.

The risks, side by side

Some risks are shared by both approaches, and they're the same ones that come with any knee replacement: infection, blood clots, heart attack, stroke, nerve or blood vessel damage, and, over the long term, implant failure.

What changes is the shape of the risk. One-sitting surgery means a longer operation, longer anesthesia, a longer first hospital stay, and more blood loss in a single go. Staged surgery means two hospital admissions, two rounds of anesthesia, and a longer overall road to having both knees healed. Neither is free. You are choosing which kind of burden to carry, and when.

Worth knowing too: Rothman notes that complication risk is higher in men and in older patients, which is part of why age and sex come into the surgeon's thinking on this question.

How recovery differs

Two new knees at once is a heavier first few weeks. Rothman describes both legs being rehabilitated together, often starting without full weight bearing and sometimes with a wheelchair at first. It lists a hospital stay of up to ten days for same-day surgery, compared with three to five days for a staged operation, and notes that some patients go on to a rehabilitation facility before home. Harvard Health puts the pace of recovery at about three to six months to feel mostly recovered, and up to a year for full recovery.

Staged surgery spreads that load out. Harvard Health notes that many patients go home the same day or the next after a single-knee operation, with physical therapy starting at home and moving to outpatient sessions. The trade-off is two hospital stays, two rounds of anesthesia, and a longer total timeline from first surgery to second knee fully healed.

One caution: these figures come from US centers. Hospital stay length and rehabilitation set-ups differ from hospital to hospital in India, so ask your own surgical team what to expect rather than treating these numbers as a promise.

The case for waiting on the second knee

There's one more thing worth knowing. Harvard Health notes that many people find the second knee improves once they've recovered from the first, and some choose to delay the second surgery for that reason.

Others have the opposite experience. Having been through the recovery once, they decide not to wait for the second knee to get worse. Both are reasonable, and neither is a mistake. The point is that you don't have to decide on the second knee before the first one is done.

Practical questions for families

A few things worth thinking through before the consultation, because they often decide the question better than any statistic:

Who can help in the first two weeks, especially if you can't put full weight on either leg? How is your home set up for stairs, low toilets, and the floor-level living many households have? How much time can you take away from work, and does recovering in one block or two suit your life better? And if sitting cross-legged on the floor is important to you, that goal needs to be planned for both knees, not just one.

Questions worth asking your surgeon

Because this is a decision made with your surgeon rather than for you, it helps to arrive with specific questions:

Is my heart and lung health good enough for one sitting, and what tests will you want first? If you were in my position, would you choose one surgery or two, and why? How long will I be in hospital and will I need a rehabilitation stay in either case? What does the first fortnight at home realistically look like, and who needs to be there? And if we stage the surgeries, how long would you want me to wait before the second knee?

None of these has a universal answer. That's exactly why they're worth asking.

What this looks like at Shaurya Hospital

At Shaurya Hospital, "Dr. Jigar D. Shah" has performed more than 20,000 joint replacement surgeries over 23-plus years. When both knees are affected, the starting point is the same as for any knee replacement: imaging first, an assessment of your overall health, and an honest conversation about whether one surgery or two suits you.

If both of your knees hurt and you've been told you'll need replacements, bring your X-rays and a list of the questions above to the consultation, and ask directly which option your surgeon would choose for you and why.

Book a consultation with Dr. Jigar D. Shah at Shaurya Hospital, Paldi, Ahmedabad, to talk through the best plan for both knees. Learn more about Joint Replacement at Shaurya Hospital.