Bilateral (Double) Knee Replacement: Both Knees at Once or Apart?
Key takeaways
- A bilateral knee replacement replaces both knees, either in one operation (simultaneous) or as two separate operations (staged).
- Simultaneous surgery means one anaesthetic and one recovery but a harder early recovery and slightly higher risks.
- Staged surgery is usually weeks to months apart and lets you recover one knee before the other.
- Each knee replacement takes about 1 to 2 hours, and full recovery for each takes 6 to 12 months.
- Suitability depends on your fitness and health, so the choice is made individually with your surgeon.
By Margaret Doyle | Medically reviewed by Mr Paul Henderson, FRCS (Tr&Orth)
Published May 13, 2026 · 4 min read
A bilateral (double) knee replacement replaces both knees, either in one operation (simultaneous) or as two separate operations (staged), with the choice depending on your fitness and health. Both are routine, and each knee follows the usual recovery: walking aids for 2 to 6 weeks and full recovery in 6 to 12 months1. Each knee replacement itself takes about 1 to 2 hours2.
Many people who need a knee replacement have arthritis in both knees, and the obvious question is whether to do them together or one at a time. I only needed one knee done, but I sat in waiting rooms with several people facing exactly this decision, and the trade-offs were not explained clearly to them. This guide, checked by a consultant orthopaedic surgeon, lays them out. For the procedure itself, start with our knee replacement surgery guide.
Simultaneous or staged: the two approaches
Bilateral knee replacement is done either simultaneously, with both knees in one operation under one anaesthetic, or staged, as two separate operations weeks to months apart. Both are recognised, and the decision is individual.
| Approach | What it means |
|---|---|
| Simultaneous bilateral | Both knees replaced in one operation, one anaesthetic, one hospital stay and recovery |
| Staged bilateral | Two separate operations, usually weeks to months apart, recovering one knee before the other |
Osteoarthritis, which often affects both knees, is the most common reason for surgery, and NICE sets out how it is assessed and managed3. Whether both knees are bad enough to replace, and whether together or apart, is decided with your surgeon.
The pros and cons of doing both at once
Simultaneous surgery means one anaesthetic, one hospital stay, and one recovery period, but a harder early recovery and a slightly higher overall risk. The trade-off is convenience against intensity.
The advantages:
- One operation and one recovery: you go through the demanding timeline once.
- One anaesthetic and one hospital admission: rather than two.
- No imbalance later: both knees are corrected together.
The drawbacks:
- A harder early recovery: you cannot lean on a good leg, so walking and stairs are tougher at first.
- A slightly higher overall risk: more blood loss and more demand on the heart and lungs make it a bigger operation, usually offered to fitter patients.
- More help needed at home: plan support and equipment in advance.
For any single knee, the main risks are similar either way: a deep infection affects about 1 to 2 in 100 people, and clots are reduced with blood thinners and early movement2.
The pros and cons of staging the operations
Staged surgery lets you fully recover one knee before the other, which is gentler and spreads the risk, but means going through the recovery timeline twice. It is often advised for older or less fit patients.
The advantages are that you always have one stronger leg to lean on during each recovery, the demand on your body at any one time is lower, and it suits people with health conditions that raise anaesthetic risk. The main drawback is time: two operations, two hospital stays, and two recovery periods, usually weeks to months apart. Some people also find the second operation harder mentally, knowing exactly what is coming. For what each recovery feels like, see our knee replacement recovery timeline.
Recovery after a double knee replacement
Each knee follows the standard recovery curve, so a double procedure means going through that timeline once (simultaneous) or twice (staged). You will use walking aids for 2 to 6 weeks, return to most normal activities within about 3 months, and reach full recovery in 6 to 12 months2.
After simultaneous surgery the early weeks are the most demanding part, because you cannot offload onto a good leg, so planning help and home setup matters even more. Versus Arthritis emphasises that physiotherapy and the daily bending exercises drive a good outcome, and that holds for both knees4. For preparing your home and yourself, see preparing for knee replacement surgery.
Who is suitable, and how long the implants last
Simultaneous surgery is generally offered to fitter, well patients with both knees severely affected, while older or less fit patients are usually advised to stage the operations. Suitability is decided individually by your surgeon and anaesthetist after assessing your health.
Whichever route you take, each implant lasts the same as a single one: typically 15 to 20 or more years, with around 90 to 95% still in place at 10 years5. Having both knees done does not shorten how long either lasts, and the same long-term care protects both. See caring for your new knee long-term for the habits that help each implant last, and how long a knee replacement lasts for the longevity data in full.
References
- Knee replacement: Recovery, NHS. ↩
- Total Knee Replacement (OrthoInfo), American Academy of Orthopaedic Surgeons. ↩
- Osteoarthritis in over 16s: diagnosis and management (NG226), NICE. ↩
- Knee replacement surgery, Versus Arthritis. ↩
- How long does a knee replacement last?, National Joint Registry. ↩
Common questions
Is it better to have both knees replaced at once?
There is no single right answer: it depends on your fitness and health. Having both knees replaced in one operation (simultaneous bilateral) means one anaesthetic, one hospital stay, and one recovery period, but the early recovery is harder because you cannot lean on a good leg, and the risks are slightly higher. Staging the two operations weeks to months apart is gentler and often advised for older or less fit patients. Your surgeon weighs this up individually.
How long does it take to recover from a double knee replacement?
Each knee follows the usual recovery curve: walking aids for 2 to 6 weeks, most normal activities back within about 3 months, and full recovery in 6 to 12 months. With simultaneous surgery both knees recover together, so the early weeks are demanding but you go through the timeline once. With staged surgery you go through it twice, weeks or months apart. Either way, full recovery for each knee takes 6 to 12 months.
Is a bilateral knee replacement more dangerous?
Doing both knees in one operation carries a slightly higher overall risk than a single replacement, because it is a bigger operation with more blood loss and a higher demand on the heart and lungs, so it is generally offered to fitter patients. Staging the operations spreads that load. For any single knee, the main risks are similar: a deep infection affects about 1 to 2 in 100 people, and clots are reduced with blood thinners and early movement. Your surgeon assesses which approach is safest for you.
Can you walk after having both knees replaced at once?
Yes, but it is harder than after a single knee replacement because you cannot put most of your weight on a good leg. A physiotherapist gets you standing and taking steps with a frame the day of or the day after surgery, and you use walking aids for 2 to 6 weeks. You will likely need more help at home in the first weeks, so planning support and equipment in advance matters more for a double procedure.
How long do double knee replacements last?
Each implant lasts the same as a single one: typically 15 to 20 or more years, with around 90 to 95% still in place at 10 years. Having both knees done does not shorten how long either implant lasts. The same long-term care applies to both: a healthy weight, low-impact exercise, strong muscles, and prompt treatment of infections all help each replacement reach its full lifespan.
Who is suitable for a simultaneous double knee replacement?
Simultaneous surgery is generally offered to patients who are otherwise fit and well, with both knees severely affected, and without significant heart, lung, or other health conditions that raise anaesthetic risk. Older or less fit patients, or those with significant medical conditions, are usually advised to stage the operations instead. Suitability is decided individually by your surgeon and anaesthetist after assessing your health.
Written by Margaret Doyle. Medically reviewed by Mr Paul Henderson, FRCS (Tr&Orth).
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