Most knee replacements last a very long time – about 82% are still working at 25 years. When one fails, usually because of infection, loosening or instability, a revision knee replacement removes some or all of the old implant and puts in a new one. It is a bigger operation than the first, and finding the exact cause of failure – especially ruling out infection – is the most important step.
This guide from the knee team at Sports Orthopedics Institute, Bengaluru explains why knee replacements fail, the warning signs, how revision surgery is planned and performed, and what results to expect.
Key takeaways
- Knee replacements usually last well: registry data show about 93% working at 15 years and 82% at 25 years.
- The commonest reasons for revision are infection, loosening and instability.
- Infection must always be ruled out before revision – with blood tests and fluid from the knee.
- Infected knees are treated with either a one-stage or two-stage revision; re-infection rates are similar (around 8–9%).
- Revision results are good but less predictable than a first replacement – around four in five revision knees still work at 10 years.
How Long Does a Knee Replacement Last?
Longer than many people think. A Lancet systematic review and meta-analysis of national joint registries, including nearly 300,000 total knee replacements, found that about 93% were still in place at 15 years, 90% at 20 years and 82% at 25 years (Lancet, 2019; NIHR summary).
Partial (unicompartmental) knee replacements are revised more often – about 70% last 25 years. Younger, more active patients are more likely to need a revision in their lifetime simply because they live longer with the implant.
Why Do Knee Replacements Fail?
Infection, loosening and instability are the most common reasons worldwide. In an analysis of international arthroplasty registers, the leading causes of knee revision were (Arch Orthop Trauma Surg, 2024):
|
Cause |
Share of knee revisions |
|---|---|
|
Deep infection |
21.6% |
|
Aseptic loosening (implant coming loose without infection) |
18.3% |
|
Instability |
14.1% |
|
Pain without another clear cause |
10.9% |
|
Implant breakage, technical error, others |
Remaining revisions |
Timing matters: infection is the leading cause of early failure, while loosening and instability are the most frequent causes overall (J Orthop, 2020).
Other causes include fractures around the implant (periprosthetic fractures), stiffness, problems with the kneecap and its tendons, and wear of the plastic insert.
Warning Signs of a Failing Knee Replacement
- New or worsening pain, especially after a period of good function
- Pain at rest or at night – a possible sign of infection or loosening
- Swelling, warmth or redness of the knee
- The knee giving way or feeling wobbly, especially on stairs
- Loss of movement or increasing stiffness
- Wound problems: discharge or a non-healing wound
- Fever or feeling unwell with a painful knee – seek prompt review
Not every painful knee replacement needs revising. Some pain comes from the back, hip or soft tissues, so a careful assessment is essential.
How the Cause Is Found
Revision should only be done when the cause of the problem is clear. Revising a knee without a clear reason often fails to relieve pain.
Ruling out infection – always the first step
- Blood tests: inflammatory markers (CRP and ESR)
- Joint aspiration: fluid is drawn from the knee to count white cells and grow any bacteria
- Further tests on the fluid when results are unclear
Imaging
- X-rays, compared with earlier films, to look for loosening, bone loss, wear or fracture
- CT scan to check implant position and rotation, and bone loss
- Bone scans occasionally, to look for loosening
MRI is less useful because the metal implant distorts the images.
Types of Revision Surgery
|
Type |
What's done |
Typical reason |
|---|---|---|
|
Insert (liner) exchange |
Only the plastic insert is changed |
Plastic wear in a well-fixed implant; sometimes with washout for early infection |
|
Partial revision |
One metal component is replaced |
One loose or badly positioned component |
|
Full revision |
All components replaced, often with stems and augments |
Loosening, instability, bone loss |
|
Complex revision |
Hinged implants, bone grafts, cones or sleeves |
Severe bone loss, ligament failure, multiple previous revisions |
|
Revision for infection |
One-stage or two-stage exchange |
Deep infection |
In the Norwegian registry, replacing the whole implant had a lower risk of needing another revision than replacing only one component (Acta Orthop, 2015).
Treating an infected knee replacement
- Early infection (within weeks of surgery, or a sudden new infection): sometimes treated by washout, changing the plastic insert and keeping the implant (DAIR), with prolonged antibiotics
- Two-stage revision: the implant is removed and a temporary antibiotic-loaded cement spacer inserted; after weeks of antibiotics and confirmation the infection has settled, a new knee is implanted
- One-stage revision: the old implant is removed, the knee thoroughly cleaned, and a new implant inserted in the same operation
Two-stage revision has long been considered the standard, but a meta-analysis of over 5,500 patients found similar re-infection rates: 7.6% after one-stage and 8.8% after two-stage revision, with similar knee function (PLOS ONE, 2016). The choice depends on the organism, the soft tissues and the patient's health.
The Operation
Revision knee replacement typically takes 2–4 hours under spinal or general anaesthesia.
- Approach: usually through the old scar; occasionally a more extensive approach is needed for a stiff knee
- Samples: tissue samples are sent for infection testing
- Implant removal: the old components and cement are removed carefully to preserve as much bone as possible
- Rebuilding bone loss: using metal augments, cones or sleeves, or bone graft
- New implant: revision implants often have stems into the bone for extra fixation, and more built-in stability (constraint) where ligaments are weak – in severe cases a hinged knee
- Balancing and closure: the knee is checked for stability and movement before closure
Before surgery
- Medical optimisation: diabetes control, anaemia correction, stopping smoking, dental and skin checks
- Review of blood thinners and other medicines
- Pre-operative exercises to strengthen the thigh muscles
Recovery Timeline
|
Time |
What to expect |
|---|---|
|
Days 1–7 |
Hospital stay usually 3–7 days; walking with a frame from day 1 if possible; pain relief; blood clot prevention |
|
Weeks 1–6 |
Walking with a frame or crutches; physiotherapy for movement and swelling; weight-bearing may be limited after complex reconstruction or fracture |
|
Weeks 6–12 |
Walking with less support; strengthening; return to driving and light activities when safe |
|
3–6 months |
Most daily activities; continued improvement in strength and stamina |
|
Up to 1 year |
Final result; swelling and discomfort continue to settle |
Recovery is usually slower than after a first knee replacement, and after a two-stage revision the overall timeline is longer.
Results and Risks
Revision knee replacement usually improves pain and function, but results are less predictable than after a first replacement.
How long do revision knees last?
- In the Norwegian registry, 85% of aseptic revisions were still working at 5 years, 78% at 10 years and 71% at 15 years. Infection was the most common reason for another revision, followed by instability (Acta Orthop, 2015).
- Revisions for infection have poorer results: in one 10-year study, survival was 86.5% after septic revision compared with 95.5% after aseptic revision, with worse function and higher mortality in the infected group (J Orthop Surg Res, 2021).
- Younger patients and men have a higher risk of needing further revision; patients 50 or younger had about a 1 in 3 risk of re-revision by 10 years in one series (published series, 2019).
Risks
- Infection – higher than after a first knee replacement; the main reason for re-revision
- Instability or stiffness
- Loosening of the new implant over time
- Fracture during or after surgery
- Wound healing problems, especially with multiple previous scars
- Blood clots, nerve or blood vessel injury – uncommon
- Persistent pain in some patients
Living With a Revision Knee
- Stay active with low-impact exercise: walking, cycling, swimming
- Avoid high-impact sport such as running and jumping
- Keep a healthy weight to reduce load on the implant
- Protect against infection: treat skin, dental, urinary and chest infections promptly, and tell other doctors you have a knee replacement
- Attend regular follow-up with X-rays to monitor the implant
Questions to Ask Your Surgeon
- What exactly has caused my knee replacement to fail?
- Has infection been ruled out, and how?
- Will all or only part of the implant be changed?
- Will I need one operation or two?
- How many revision knee replacements do you perform?
- What results and recovery time should I expect?
How Sports Orthopedics Institute Can Help
Our knee team in HSR Layout, Bengaluru assesses painful and failing knee replacements systematically – including infection work-up and CT planning – and performs partial, full and complex revisions, including one- and two-stage revision for infection.
Book at sportsorthopedics.in or call +91 6364538660 / +91 9008520831.
Frequently Asked Questions
How long does a knee replacement last?
About 93% are still working at 15 years, 90% at 20 years and 82% at 25 years, according to pooled national registry data.
What are the signs my knee replacement is failing?
New or worsening pain, pain at night or rest, swelling, warmth, the knee giving way, or loss of movement. Fever or wound discharge needs urgent review.
Is revision surgery more difficult than the first operation?
Yes. It takes longer, often involves bone loss and scar tissue, and may need special implants. Recovery is usually slower.
How long does revision surgery take?
Usually 2–4 hours, depending on complexity.
Will I need two operations if my knee is infected?
Not always. Many infections are treated with a two-stage revision, but one-stage revision has similar re-infection rates in suitable patients. Your surgeon will advise based on the type of infection and your health.
How long does a revision knee last?
About 78% of aseptic revisions are still working at 10 years and 71% at 15 years in registry data. Results are poorer after revision for infection and in younger patients.
When can I walk after revision surgery?
Usually from the day after surgery with a frame, though weight-bearing may be limited after complex reconstruction.
What activities can I do afterwards?
Walking, cycling, swimming and gentle exercise. Avoid running and jumping sports.
References
- Evans JT, et al. How long does a knee replacement last? A systematic review and meta-analysis of case series and national registry reports. Lancet, 2019;393:655–663.
- Causes of revision in hip and knee arthroplasty using worldwide arthroplasty registers. Arch Orthop Trauma Surg, 2024.
- Mathis DT, Hirschmann MT. Why do knees after total knee arthroplasty fail in different parts of the world? J Orthop, 2020.
- Kunutsor SK, et al. Re-infection outcomes following one- and two-stage surgical revision of infected knee prosthesis: a systematic review and meta-analysis. PLOS ONE, 2016.
- Failure of aseptic revision total knee arthroplasties: 145 revision failures from the Norwegian Arthroplasty Register. Acta Orthop, 2015.
- Baek JH, et al. Poor outcomes of revision TKA in patients with septic loosening compared to aseptic loosening. J Orthop Surg Res, 2021.
- Contemporary revision TKA in patients younger than 50 years: 1 in 3 risk of re-revision by 10 years, 2019.
Disclaimer: This article is for general information and does not replace advice from a qualified orthopedic surgeon.