A revision knee replacement is an operation to redo a knee replacement: part or all of the old implant is taken out and replaced. The usual reasons are an implant that has
- LOOSENED or worn,
- an infection,
- a knee that feels unstable,
- stiffness, or
- a break in the bone around the implant
Honestly, most knee replacements never need it.
Around 8 in 10 are still going at 25 years. But when a revision is needed, it is a bigger operation than the first one, recovery takes LONGER, often 3 months to a year, and the result is less predictable.
Most people still get good pain relief. The best results come when there is a clear, fixable reason for the problem.
Why a knee replacement may need redoing
- Loosening and wear: over years, the bond between implant and bone can fail, or the plastic spacer can wear. The knee becomes painful, often when you first stand and start walking. Infection and loosening are among the most common reasons for revision
- Infection: can show up soon after surgery or years later, sometimes after an infection elsewhere in the body travels to the knee through the blood
- Instability: the knee feels wobbly or gives way, often because the ligaments around it are too loose or the parts aren’t balanced
- Stiffness: heavy scar tissue stops the knee bending or straightening enough for daily life. Most stiff knees are managed without a revision. See stiff knee after knee replacement
- A break around the implant, usually after a fall
How surgeons work out the cause
- X-rays over time to look for loosening, wear or a fracture
- Blood tests for signs of infection
- Drawing fluid from the knee with a needle to test for infection. This is one of the most important tests, because infection changes the whole plan
- Sometimes scans, to look at bone and implant position
If the tests find no clear cause for the pain, many surgeons are cautious about operating. Redoing a knee for unexplained pain tends to give disappointing results.
What’s different about the operation
- Longer surgery: usually around 2 to 3 hours, longer than a first knee replacement
- Bone loss: taking out the old implant can leave gaps in the bone. Surgeons fill them with metal blocks, bone graft or longer stems that reach further into the bone
- Several days in hospital is typical, usually longer than the first time
- For infection, often two operations: the first removes the implant, cleans the joint and places a temporary spacer loaded with antibiotics. You then have several weeks of antibiotics, often through a drip, before the second operation puts in the new knee. Some people have it done in a single stage instead
The American Academy of Orthopaedic Surgeons has a clear guide to revision total knee replacement.
A revision fixes a reason. Without a clear reason, it rarely fixes the pain.
How recovery is different
The basics are the same as the first time: get the knee straight, keep bend coming, control swelling and rebuild the thigh muscle. See knee replacement recovery week by week. What changes is the pace and the rules. Your surgeon’s protocol comes first. Use theirs.
- Weight on the leg may be limited for some weeks if bone graft was used or a fracture was fixed. After a simpler revision, you may be allowed full weight straight away
- A brace is sometimes used early on
- Physio usually runs for up to about 3 months, sometimes longer
- Full recovery takes anywhere from about 3 months to a year. Expect it to take longer than your first knee
- Between two stages for infection, walking and bending with a spacer may be restricted. Your team will tell you what’s allowed
- Muscles start weaker. If the knee was failing for months before the revision, the thigh muscle may be very thin. Strength work matters even more
What to expect afterward
- Most people have good long-term results, including relief from pain
- Some pain, stiffness or looseness can remain, more often than after a first knee replacement
- Complications are more common than the first time, including infection, fracture and loosening
- A revision doesn’t last as long as a first knee. Roughly 1 in 5 revised knees need another operation within about 13 years, more often in younger men
Questions to ask your surgeon
- What exactly has gone wrong, and how sure are we?
- Has infection been ruled out?
- Will this be one operation or two?
- How many revision knee replacements do you do each year?
- What is a realistic result for me?
For a fuller list, see questions to ask before orthopedic surgery.
Call your surgeon today if
- The wound is red, spreading, hot, weeping or draining, or you have a fever or chills
- The knee becomes hotter, more swollen and more painful, at any point after surgery, even years later
- Your calf is painful, tender or newly swollen. It could be a clot in the leg
- The knee suddenly gives way or clunks, or you can’t put weight on it after a fall
Go to the emergency department if
- You are suddenly short of breath or have chest pain. A clot can travel to the lung
- You feel very unwell with a high fever, shaking or confusion
Mention it at your next review if
- An old knee replacement has started to ache when you first stand up and walk
- The knee feels wobbly on stairs or slopes
- Bend has stalled well short of 90 degrees
The second knee operation is bigger and slower than the first. It works best when the reason is clear.