Younger patients enquring about knee replacement are usually cautioned about the natural lifespan of the prosthesis, and the possibility that the younger patient may need one, or even two, revisions during their life.
How long does a knee replacement last?
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.
How long does a knee replacement last? A systematic review and meta-analysis of case series and national registry reports with more than 15 years of follow-up. Evans JT, Walker RW, Evans JP, Blom AW, Sayers A and Whitehouse MR. Lancet. 2019; 393(10174): 876.
Complications of total knee replacement
The most common cause of revision of the original procedure is aseptic loosening.
A 2013 publication listed 22 complications of sufficient severity that surgeons felt that they should be reported to the outcomes registries:
- problems with wound healing
- symptomatic thromboembolic events
- nerve damage
- vascular injury
- medial collateral ligament injury
- knee instability
- symptomatic angular deformity
- infections around the implants
- fractures around the implants
- extensor lag
- patellofemoral dislocation
- tibiofemoral dislocation
- bearing surface wear
- implant loosening
- implant fracture or dissociation of the tibial insert from the tibial implant
Complications of Total Knee Arthroplasty: Standardized List and Definitions of The Knee Society Healy WL, Della Valle CJ, Iorio R, Berend KR, Cushner FD, Dalury DF and Lonner JH. Clin Orthop Relat Res. 2013 Jan;471(1):215-20.
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 -
- problems with extension
- aseptic loosening
- poor alignment or positioning
Failure following revision total knee arthroplasty: infection is the major cause. Mortazavi SMJ, Molligan J, Austin MS, Purtill JJ, Hozack WJ and Parvizi J. Int Orthop. 2011 Aug; 35(8): 1157–1164.
Causes and Clinical Outcomes of Revision Total Knee Arthroplasty. Lee D-H, Lee S-H, Song E-K, Seon J-K, Lim H-A and Yang H-Y. Knee Surgery & Related Research 2017 Jun; 29(2): 104-109.
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.
Metallosis in a total knee arthroplasty. Vivegananthan B, Shah R, Karuppiah AS and Karuppiah SV. BMJ Case Report,2014.