If a knee replacement fails it may have to be removed and replaced. This is the main reason why surgeons counsel patients to wait before undergoing knee replacement if they are still young.

Page updated February 2024 by Dr Sheila Strover (Clinical Editor)


How long does a knee replacement last?

Younger patients enquring about knee replacement are usually cautioned about the natural lifespan of the prosthesis, and the possibility that they might need one, or even two, revisions during their life.

A 2019 publication (below), based on figures obtained from the National Joint Registry for England, Wales, Northern Ireland, and Isle of Man and the Royal College of Surgeons of England, suggests that approximately 82% of total knee replacements last 25 years and 70% of unicompartmental knee replacements last 25 years.

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Complications of total knee replacement

The most common cause of revision of the original procedure is aseptic loosening.

Many developed countries maintain National outcomes registries, to which the surgeon is obligated to report any complications.

Twenty-two complications are considered of sufficient severity that they should be reported to the outcomes registries: 

  1. bleeding
  2. problems with wound healing
  3. symptomatic thromboembolic events
  4. nerve damage
  5. vascular injury
  6. medial collateral ligament injury
  7. knee instability
  8. symptomatic angular deformity
  9. stiffness
  10. infections around the implants
  11. fractures around the implants
  12. extensor lag
  13. patellofemoral dislocation
  14. tibiofemoral dislocation
  15. bearing surface wear
  16. osteolysis
  17. implant loosening
  18. implant fracture or dissociation of the tibial insert from the tibial implant
  19. reoperation
  20. revision
  21. readmission
  22. death

This information, together with details of the manufacturer and exact make and reference numbers of the components, mean that there is constant evaluation and improvement in design.

  • Quote from peer-reviewed paper:

    "....Generally, data from registries are provided back to hospitals, clinics and clinicians which then facilitate comparisons with local, regional, or even national benchmarks....."

    Citation: Etkin CD, Springer BD. The American Joint Replacement Registry-the first 5 years. Arthroplast Today. 2017 Mar 14;3(2):67-69. doi: 10.1016/j.artd.2017.02.002. PMID: 28695176; PMCID: PMC5485224.

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Causes of total knee replacement failure

The knee replacement would be deemed to have failed if revision or removal is considered for any of the following reasons -

  • infection - infection after knee replacement requires draining and irrigation with antibiotic solutions. It may become necessary to remove the hardware and let the joint settle down before revising the procedure.
  • stiffness
  • problems with extension
  • fracture
  • aseptic loosening
  • poor alignment or positioning
  • instability


  • Quote from peer-reviewed paper:

    "....infection has become the primary acute cause of failure with loosening and instability remaining as the overall greatest reasons for revision....."

    Citation: Lum ZC, Shieh AK, Dorr LD. Why total knees fail-A modern perspective review. World J Orthop. 2018 Apr 18;9(4):60-64. doi: 10.5312/wjo.v9.i4.60. PMID: 29686970; PMCID: PMC5908984.

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Metallosis in relation to knee replacement

Metallosis is an uncommon disorder of total knee replacement where fine metal debris is deposited in the joint, causing pain and synovitis

Suspicion of this diagnosis may follow  -

  • positive tests for metal allergy, especially nickel and cobalt
  • ‘bubble sign’, ‘cloud sign’ and the ‘metal line sign’ on X-rays
  • associated tissue swelling and rashes

The knee replacement procedure may require revision using a prosthesis manufactured from different metals.

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Dr Sheila Strover (Editor)
BSc (Hons), MB BCh, MBA

See biography...