Revision surgery can be needed for different reasons, including infection, loosening, instability, plastic spacer wear, fracture, stiffness, or persistent pain that does not improve as expected.
This article explains why a knee replacement may need revision surgery, what warning signs to watch for, and why identifying the cause matters before deciding on the next step.
Quick Answer
A revision knee replacement is a surgery to repair, replace, or adjust a previous knee replacement. It may be needed if the implant becomes infected, loose, unstable, worn, painful, stiff, fractured around, or mechanically problematic.
Revision surgery is usually more complex than the first knee replacement, so the most important first step is figuring out why the knee replacement is not working well.
Key Takeaways
- Most knee replacements do not need early revision surgery.
- Revision may be needed for infection, loosening, instability, wear, fracture, stiffness, or persistent unexplained pain.
- New pain, new swelling, instability, fever, drainage, or a major change in walking ability should be taken seriously.
- The cause of the problem matters because treatment is different for infection, loosening, stiffness, instability, or fracture.
- Revision surgery is usually more complex than the original knee replacement.
What Is a Revision Knee Replacement?
A revision knee replacement is a second surgery on a knee that already has a replacement.
Sometimes only one part of the implant needs to be exchanged. Other times, multiple components need to be removed and replaced. In more complex cases, the surgeon may need special implants, stems, augments, or bone reconstruction techniques to restore stability and function.
AAOS explains that revision total knee replacement may be needed when a previous knee replacement fails because of problems such as infection, pain, loosening, or instability. AAOS revision total knee replacement overview
The goal is to address the reason the knee replacement is failing or not functioning well.
Why Would a Knee Replacement Need to Be Redone?
A knee replacement may need revision surgery when the implant or surrounding tissues are no longer working as they should.
The reason matters. A knee that is painful because of infection is treated differently than a knee that is painful because of loosening, instability, stiffness, or fracture.
Common reasons for revision may include:
- Infection around the implant.
- Loosening of implant components.
- Instability or repeated giving way.
- Wear of the plastic spacer.
- Fracture around the implant.
- Stiffness or severe loss of motion.
- Implant malposition, poor fit, or mechanical problems.
- Persistent pain that requires further evaluation.
AAHKS notes that revision surgery can be needed for infection, loosening, instability, wear, and fracture, and that revision procedures are often longer and more complex than the original knee replacement. AAHKS revision knee replacement overview
Reason 1: Infection
Infection is one of the most serious reasons a knee replacement may need revision surgery.
An infection can happen early after surgery or later. Later infections may occur if bacteria enter the bloodstream and settle around the implant.
Possible signs of infection include:
- Fever or chills.
- Drainage from the incision.
- Worsening redness around the knee or incision.
- Increasing warmth around the knee.
- Rapidly worsening swelling or pain.
- A major change in how the knee feels or functions.
AAHKS reports that infection after a first-time knee replacement is uncommon, but if it occurs, it often requires prompt treatment and may not be adequately treated with simple antibiotics alone. AAHKS infection and knee replacement overview
Why infection can be difficult
Bacteria can attach to implant surfaces and form a protective layer called a biofilm. This can make the infection harder to treat with antibiotics alone.
Treatment depends on timing, severity, the organism involved, the condition of the implant, and the person’s overall health. Some infections may be treated with irrigation, cleaning, liner exchange, and antibiotics. Others may require removing the implant and placing a temporary spacer before a new implant is placed later.
Reason 2: Loosening
Loosening means the implant is no longer securely fixed to the bone.
This can happen over time because of mechanical stress, bone changes, wear particles, implant positioning, or other factors. Sometimes the exact cause is not obvious.
Possible signs of loosening include:
- New or worsening pain with weight bearing.
- Pain that gradually gets worse over time.
- Swelling that does not match recent activity.
- A feeling that the knee is less dependable.
- Reduced walking tolerance.
- Difficulty with stairs or standing after sitting.
AAOS notes that loosening may be influenced by high-impact activities, excessive body weight, and wear of the plastic spacer between implant parts. AAOS revision total knee replacement overview
If loosening is confirmed, revision surgery may involve removing the loose component and replacing it with a more stable construct.
Reason 3: Instability
Instability means the knee replacement does not feel stable or controlled.
This may happen because of ligament imbalance, component position, soft tissue changes, wear, trauma, or other mechanical issues.
Possible signs of instability include:
- The knee feels like it may give way.
- Repeated buckling.
- Difficulty walking on uneven ground.
- Reduced confidence going down stairs.
- A sense that the knee shifts or moves abnormally.
- New instability after a fall or injury.
Not every feeling of insecurity means the implant is failing. Quad weakness, swelling, balance deficits, and fear can also make a knee feel less trustworthy. But repeated giving way or a clear change in stability deserves evaluation.
Reason 4: Plastic Spacer Wear
The plastic spacer, also called the polyethylene insert, sits between the metal components of the knee replacement.
Over time, this spacer can wear. Modern materials have improved, but wear can still occur, especially over many years or with high mechanical demand.
Plastic wear may contribute to:
- Swelling.
- Discomfort.
- Instability.
- Loosening.
- Changes in how the knee moves.
In some situations, only the liner may need to be exchanged. In others, more components may need to be revised depending on wear, loosening, bone loss, and stability.
Reason 5: Fracture Around the Implant
A fracture around a knee replacement is called a periprosthetic fracture.
This can happen after a fall, trauma, or sometimes because of weakened bone. The fracture may occur around the thighbone, shinbone, or kneecap.
Warning signs after a fall or injury may include:
- Sudden severe pain.
- New inability to bear weight.
- Rapid swelling or bruising.
- Visible deformity.
- A major change in walking ability.
Treatment depends on the fracture location, whether the implant is still stable, bone quality, and the person’s health. Some fractures require fixation, while others may require revision of the implant.
Reason 6: Stiffness or Severe Loss of Motion
Stiffness is common early after knee replacement, but severe or persistent stiffness can become a major problem.
Stiffness may be related to swelling, scar tissue, pain, delayed motion, infection, implant position, or other factors.
Stiffness may be concerning when:
- Knee bending or straightening is not improving over time.
- The knee becomes harder to move instead of gradually easier.
- Motion limits walking, stairs, sitting, or daily activity.
- Stiffness is paired with worsening pain, warmth, swelling, or fever.
Some stiffness can be treated without revision surgery. Other cases may need additional treatment such as manipulation under anesthesia, scar tissue procedures, or revision if a mechanical issue is involved.
Reason 7: Poor Fit, Malposition, or Mechanical Problems
A knee replacement has to fit, align, and move well.
If the components are poorly positioned, poorly sized, not balanced well with the soft tissues, or not tracking properly, the knee may feel painful, stiff, unstable, or unnatural.
Mechanical problems may show up as:
- Pain that does not improve as expected.
- Stiffness or restricted motion.
- A feeling that the knee does not track smoothly.
- Instability or repeated buckling.
- Difficulty progressing despite appropriate rehab.
These issues require careful evaluation. Revision surgery may be considered if a correctable mechanical cause is found and symptoms are significant.
How Do You Know If a Knee Replacement Is Failing?
A painful or stiff knee replacement does not automatically mean the implant is failing.
Early recovery can include swelling, stiffness, soreness, warmth, numbness, and weakness. Even later, activity changes can cause temporary soreness or swelling.
The concern is when symptoms are new, worsening, persistent, severe, or paired with warning signs.
Warning Signs That Deserve More Caution
- New or worsening pain that does not match recent activity.
- Repeated giving way or a new sense of instability.
- Rapidly increasing swelling, warmth, redness, or worsening pain.
- Fever, chills, drainage, or signs of infection.
- New calf pain, calf swelling, chest pain, or shortness of breath.
- Sudden inability to bear weight after a fall or injury.
- A major change in walking ability.
If these symptoms occur, do not try to solve them by pushing harder through exercise. Follow your surgeon’s post-op instructions or contact your medical team.
How Is the Cause Diagnosed?
Finding the cause of a painful or problematic knee replacement usually requires a careful evaluation.
Evaluation may include:
- A detailed history of symptoms and timeline.
- Physical examination of motion, swelling, strength, alignment, and stability.
- X-rays to assess implant position, loosening, fracture, or alignment.
- Blood tests if infection is a concern.
- Joint aspiration if infection needs to be ruled out.
- Advanced imaging in selected cases.
- Review of prior surgical records and implant information.
The workup matters because revision surgery should be directed at the real problem, not just the symptom of pain.
What Happens During Revision Surgery?
Revision surgery depends on the reason for failure.
Some revisions are relatively limited, such as exchanging the plastic liner. Others are more complex and require removing well-fixed or loose components, addressing bone loss, using stems or augments, treating infection, or improving stability.
Revision surgery may involve:
- Removing one or more implant components.
- Cleaning infected tissue if infection is present.
- Using temporary spacers in some infection cases.
- Replacing worn or loose components.
- Managing bone loss or fracture.
- Using more constrained implants for instability.
- Balancing the soft tissues around the knee.
Because revision surgery is more complex than the original knee replacement, it is important to work with a surgeon who is comfortable evaluating and managing revision cases.
Can Revision Surgery Be Prevented?
Not every revision can be prevented. Infection, trauma, implant issues, medical factors, and biological factors can happen even when someone does everything right.
But you can support the long-term health of your knee replacement by making smart choices.
Helpful long-term strategies include:
- Keeping follow-up appointments with your orthopedic team.
- Building and maintaining leg strength.
- Choosing appropriate lower-impact exercise when recommended.
- Managing body weight and general health when appropriate.
- Reducing fall risk through strength, balance, and home safety.
- Taking infection symptoms seriously.
- Reporting new pain, instability, or major function changes early.
Common Mistakes
- Assuming every painful knee replacement needs revision surgery.
- Ignoring new instability, worsening swelling, or signs of infection.
- Trying to push through symptoms that are clearly getting worse.
- Assuming pain alone identifies the cause of the problem.
- Skipping follow-up appointments when the knee changes.
- Not getting a clear explanation of why revision is being recommended.
Related Learning
If you are learning about knee replacement problems, longevity, or warning signs, these articles may help:
Want a Clearer Knee Replacement Recovery Plan?
The Knee Replacement Recovery Guide includes phase-based exercise plans, progress check-ins, focus tracks, and guidance for building strength, walking tolerance, stair control, confidence, and long-term activity tolerance.
Instead of guessing how much to do or when to progress, you can follow a clearer path based on where you are in the recovery process.
FAQ
What is revision knee replacement?
Revision knee replacement is surgery to repair, replace, or adjust a previous knee replacement that is not functioning well because of problems such as infection, loosening, instability, wear, fracture, stiffness, or persistent pain.
Why would a knee replacement need to be redone?
A knee replacement may need to be redone if the implant becomes infected, loose, unstable, worn, painful, stiff, fractured around, or mechanically problematic.
How do I know if my knee replacement is failing?
Possible warning signs include new or worsening pain, repeated giving way, rapidly increasing swelling, fever, drainage, sudden inability to bear weight, or a major change in walking ability. These symptoms need evaluation; they do not automatically prove implant failure.
Is revision knee replacement harder than the first surgery?
Revision knee replacement is often more complex than the original surgery because the surgeon may need to remove old components, manage bone loss, treat infection, improve stability, or use specialized implants.
Can infection cause a knee replacement to fail?
Yes. Infection is one of the more serious reasons for revision surgery. It may require cleaning the joint, exchanging parts, antibiotics, or in some cases removing the implant and placing a temporary spacer before a new implant is inserted later.
Can revision knee replacement be avoided?
Not every revision can be prevented, but long-term follow-up, strength training, appropriate activity choices, fall prevention, infection awareness, and early evaluation of new symptoms can help protect the knee replacement.
