Bilateral Knee Replacement: Should You Replace Both Knees at Once?
Bilateral knee replacement is surgery to replace both knees with artificial implants. It can be done in a single operation (simultaneous) or as two operations spaced weeks to months apart (staged). Neither route suits everyone. The right choice depends on your age, heart and lung health, how badly each knee is affected, and the help you will have at home during recovery.
When arthritis has worn down both knees, the question is rarely just “do I need surgery?” It is also “do I do it all in one go?” This guide explains how bilateral knee replacement works, how the same-day and staged approaches compare, who may be suited to each, and what recovery usually involves, so you can have a more useful conversation with your orthopaedic surgeon.
What is bilateral knee replacement?
Bilateral knee replacement means that both knee joints are resurfaced with implants, usually because of advanced osteoarthritis, rheumatoid arthritis or arthritis after an old injury. The damaged cartilage and a thin layer of bone are removed, and metal and medical-grade plastic components take over the gliding surface of the joint.
The word “bilateral” describes only the fact that both knees are treated. It does not tell you when each knee is done. In practice, surgeons use three patterns:
| Approach | What happens | Typical use |
|---|---|---|
| Simultaneous (same-day) | Both knees are replaced in one operation under one anaesthetic, by one surgeon operating on each knee in turn or by two surgeons working side by side | Selected patients who are otherwise healthy |
| Staged during one admission | The second knee is done a few days after the first, before discharge | Selected patients, depending on the hospital’s protocol |
| Staged months apart | Two separate admissions, commonly at least about three months apart | The most common route for people with two equally painful knees |
Some patients who start with one operation find that the second knee becomes tolerable once the first is working well, and they postpone or cancel the second surgery. That is a perfectly reasonable outcome.
When do doctors consider replacing both knees?
Surgeons usually consider bilateral knee replacement when both knees have advanced arthritis, both are painful enough to limit walking, stairs or sleep, and non-surgical treatment is no longer enough.
Before surgery is discussed, most patients are first offered measures such as weight management, physiotherapy, pain relief medication and injections. If one knee is clearly worse than the other, many surgeons prefer to replace that knee first and reassess the other afterwards.
Not every painful knee needs a replacement. A torn meniscus, for example, may be treated very differently from end-stage arthritis. You can read about meniscal repair surgery and when it may help if your symptoms started with a twisting injury rather than long-standing wear.
Same-day vs staged: how do they compare?
Replacing both knees at once means one anaesthetic, one hospital stay and one rehabilitation period, but it puts more strain on the body than operating on one knee at a time. Staged surgery spreads that strain across two operations at the cost of a longer overall journey.
| Factor | Both knees at once | Two separate surgeries |
|---|---|---|
| Anaesthetics | One | Two |
| Hospital admissions | One | Two (or one longer admission if staged within it) |
| Total time away from work | Usually shorter overall | Usually longer overall |
| Early recovery | Harder: neither leg is fully strong at first | Easier: one leg stays comparatively stable |
| Strain on heart and lungs | Higher | Lower per operation |
| Blood loss | More | Less |
| Where rehab happens | More often needs a rehabilitation facility or intensive home support | More often manageable from home |
| Suits | Healthy, motivated patients with strong support | Most patients, especially those with other medical conditions |
What does the research say about safety?
The evidence is mixed, which is why surgeons weigh each patient individually rather than applying one rule. A large single-centre comparison of 1,304 patients, published in the Journal of Bone & Joint Surgery (British) in 2006, found that simultaneous surgery was not riskier than staged surgery in that group and highlighted the single anaesthetic and shorter total recovery as benefits.
More recent pooled analyses are less reassuring. A 2025 systematic review and meta-analysis covering hundreds of thousands of patients reported that simultaneous surgery was associated with lower reoperation rates and lower cost, but with higher complication and mortality rates. A 2024 network meta-analysis similarly suggested that staged surgery may be the safer option overall, while noting that results differ according to how far apart the two operations are.
The practical lesson: simultaneous surgery is not “unsafe” and staged surgery is not “risk-free”. Careful patient selection is what matters most.
Possible advantages of replacing both knees together
- One anaesthetic and one hospital admission
- One continuous period of rehabilitation instead of two
- Less total time away from work, which matters for many working-age patients
- Potentially lower overall hospital costs, depending on the centre and your insurance
- No waiting period with one knee still painful
Possible disadvantages and risks
All knee replacements carry general surgical risks, including infection, blood clots, stiffness, nerve irritation, implant problems over time and ongoing pain in some patients. With bilateral surgery, some of these risks, especially those affecting the heart, lungs and blood clotting, may be higher when both knees are done together because the operation is longer and blood loss is greater.
Other practical downsides include:
- A tougher first few weeks, because you cannot lean on a “good” leg
- A greater chance that you will need supervised rehabilitation rather than going straight home
- A possible need for blood transfusion, which is uncommon after a single knee replacement
- Higher physical and emotional demands during rehabilitation
Who may be suited to each approach?
Simultaneous surgery is generally reserved for people who are otherwise healthy, have good support at home and are prepared for a demanding recovery. Individual hospitals set their own criteria. Some centres, for example, avoid same-day bilateral surgery above about 75 years of age or at a body mass index of 40 or higher, and most require that heart, lung and kidney health are in good shape.
Staged surgery may be the more sensible route if you:
- Have heart, lung or kidney disease, diabetes that is hard to control, or a history of blood clots
- Are older or frail
- Live alone or have limited help at home
- Are very anxious about a single long operation
- Have one knee that is much worse than the other
Only a surgeon who has examined you, reviewed your X-rays and discussed your medical history can say which category you fall into. Generic information, including this article, cannot make that decision for you.
How should you prepare?
Preparation tends to make recovery smoother, and it matters even more when both knees are involved.
- Medical clearance. Expect blood tests, heart and chest assessment, and a review of your regular medicines, including blood thinners and diabetes medication.
- Strengthening (“prehab”). Your physiotherapist may suggest exercises for the thigh and hip muscles before surgery.
- Home set-up. Remove loose rugs, arrange a bedroom and bathroom on one floor if possible, and consider a raised toilet seat and a sturdy chair with arms.
- A support plan. Decide who will help in the first weeks with meals, medicines, transport to physiotherapy and getting around the house.
- Questions in writing. Bring a list to your consultation (see below).
What does recovery look like?
Most people feel mostly recovered within about three to six months after both knees are replaced together, and full recovery can take up to a year. Timelines differ from person to person, and staged recovery is usually quicker for each individual operation.
| Stage | What is commonly expected |
|---|---|
| First days | Pain control, early physiotherapy, getting out of bed and standing with support, blood clot prevention |
| First weeks | Walking with a walker or crutches, daily exercises, wound checks, swelling management |
| Around 6 to 12 weeks | Growing independence, less reliance on walking aids, return to light daily activities |
| 3 to 6 months | Most people feel mostly recovered, with improving strength and stamina |
| Up to 12 months | Continued gains in strength, range of motion and confidence |
After recovery, surgeons generally encourage low-impact activity such as walking, swimming, cycling and golf, and advise against repeated high-impact activity such as running or jumping. Your own surgeon’s advice should guide what you do.
What about cost and insurance?
The cost of bilateral knee replacement depends mainly on the hospital and room category, the surgeon’s fee, the type of implant, the length of stay and any complications. Because simultaneous and staged surgery involve different numbers of admissions, the totals can differ, and it is wise to ask for an itemised estimate for the approach you are considering.
If you plan to use health insurance, check coverage for the procedure, room rent limits, implant sub-limits and whether pre-authorisation is needed before admission.
Questions to ask your surgeon
- Is there a reason to choose same-day over staged surgery for me, or the reverse?
- How many bilateral knee replacements does the team perform, and what is their protocol for blood clot prevention?
- Will I go home or to a rehabilitation facility?
- What type of implant do you recommend and why?
- What would make you change the plan on the day of surgery?
- If we stage the surgery, how long will we wait before the second knee?
Expert perspective
[Dr Sanjay Gupta to review and, if he wishes, add 2 to 4 sentences describing his own approach to bilateral cases, such as how he decides between same-day and staged surgery and his team’s rehabilitation protocol. Do not publish this section with placeholder text.]
This article is written for patient education. Dr Sanjay Gupta is an orthopaedic surgeon specialising in knee and hip replacement. His professional background, training and memberships are listed on his profile page, and his profile states that he is Director and HOD of Orthopaedics and Joint Replacement at Max Hospital, Vaishali, and has performed more than 15,000 joint replacements. If you would like an opinion on whether one or both of your knees need surgery, you can contact the clinic to arrange a consultation.
Frequently Asked Questions
Is bilateral knee replacement a major surgery?
Yes. Replacing both knees is major orthopaedic surgery, and even when done in two stages, each operation needs anaesthesia, hospital care and structured rehabilitation. Most patients recover well with proper preparation and follow-up.
Is it safe to replace both knees at the same time?
It can be, for carefully selected patients. Studies disagree on how much extra risk same-day surgery carries, but several reviews report more complications than staged surgery. Your surgeon will weigh your heart, lung and general health before recommending it.
How long should I wait between two knee replacements?
There is no fixed rule. Many surgeons suggest waiting at least about three months, by which time the first knee has usually recovered most of its strength, but your surgeon may recommend a different interval depending on your health and progress.
How long does recovery take after both knees are replaced?
Many patients feel mostly recovered in three to six months, and full recovery may take up to a year. Walking aids, physiotherapy and supervised rehabilitation are usually needed in the early weeks.
Will I go home or to a rehabilitation centre afterwards?
It depends on your fitness and home support. After a single knee replacement many people go straight home, whereas after both knees at once some patients are advised to spend time in a rehabilitation facility or arrange intensive help at home.
Can I replace only one knee and wait?
Often, yes. If one knee is much more painful, surgeons commonly replace that one first. Some patients later find the other knee manageable and delay or avoid a second operation, while others go ahead once they have recovered.
Can both knees have partial knee replacement?
In selected patients with damage limited to one part of the knee, partial replacement may be possible in both knees. Partial replacement is less extensive but may carry a higher chance of needing further surgery later, so suitability needs specialist assessment.
Is bilateral knee replacement covered by health insurance?
Cover varies by policy. Many insurers cover medically necessary knee replacement, but room rent limits, implant sub-limits and waiting periods can apply. Ask your insurer about pre-authorisation before admission.
Conclusion
Bilateral knee replacement can relieve pain and restore movement when arthritis affects both knees, but the timing deserves as much thought as the decision to operate. Doing both knees together offers convenience and one recovery, while staged surgery generally places less strain on the body. The safest plan is the one your surgeon builds around your health, your knees and your support at home. If you are weighing this decision, a personal consultation and imaging review will tell you far more than any general guide.
