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knee replacement surgery

NIHR Signal More than 80% of total knee replacements can last for 25 years

Published on 11 June 2019

doi: 10.3310/signal-000776

Large data sets from national registries and case series show that about 82% of total knee replacements and 70% of partial (unicompartmental) knee replacements last for 25 years.

This NIHR-funded review of that data is the first to demonstrate longer-term effectiveness of these procedures. This means that the operation, which aims to relieve pain for osteoarthritis, may not need to be delayed to reduce the chance of a patient needing further surgery at a later date. It is an encouraging finding for an ageing population.

This study didn’t include data from the UK, as the National Joint Register of England, Wales, Northern Ireland and the Isle of Man didn’t go back far enough for this analysis. However, there is no reason to suspect that UK data, which is being collected, would be much different.

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Why was this study needed?

Knee replacement surgery is a routine operation to replace a worn or damaged knee joint with an artificial one. The most common reason for needing surgery is osteoarthritis. Total knee replacement is where both sides of the knee joint are replaced. Unicompartmental knee replacement involves just one side of the knee joint being replaced. A variety of components and methods of fixing can be used.

In 2017 there were 106,334 knee replacement procedures carried out in England, Wales and Northern Ireland. The average age of patients was 69 years. There were also 6,502 knee revision procedures, where people needed a second operation. Further surgery on elderly patients should be avoided if possible, so it is important to know how long a knee replacement can be expected to last. Research to date only gives estimates for 15 and 20 years. This study looked at longer-term data.

What did this study do?

This study was made up of a systematic review and meta-analysis of published case series, and a meta-analysis of data from national joint registries. The authors found 33 case series, with a total of 7,232 knee replacements. Twenty-six case series looked at total replacement, while seven reported survival of unicompartmental replacement. Data from the Australian and Finnish national registries were used, with a total of 299,291 total replacements, and 7,714 unicompartmental.

The quality of the published case series was low. And only the Finnish registry had outcomes data at 20 and 25 years.

What did it find?

Data from the national registries provided the most reliable results:

  • For total knee replacements, 93.0% were still intact at 15 years (95% CI 92.8 to 93.1; Australian and Finnish registries with 299,291 replacements). At 20 years, 90.1% of replacements had survived (95% CI 89.7 to 90.4; Finnish registry with 88,532 replacements). 82.3% of replacements were still intact at 25 years (95% CI 81.3 to 83.2; Finnish registry with 76,651 replacements).
  • For unicompartmental replacements, 76.5% were still intact at 15 years (95% CI 75.2 to 77.7; Finnish registry with 7,714 procedures). At 20 years, 71.6% had survived (95% CI 69.6 to 73.6; Finnish registry with 3,935 replacements). 69.8% were still intact at 25 years (95% CI 67.6 to 72.1; Finnish registry with 3,935 replacements).

What does current guidance say on this issue?

The British Orthopaedic Association and Royal College of Surgeons published a commissioning guide for painful osteoarthritis of the knee in 2017.

It says that total knee replacements should only be considered for patients whose pain has not been adequately controlled by three months of non-surgical management (based on NICE guidance for managing osteoarthritis).

It states that joint survival is 95% at seven years. It also says that unicompartmental knee replacement has a lower joint survival than total replacement.

What are the implications?

This study provides evidence that knee replacement surgery has better long-term outcomes than was previously thought. The average age of someone in the UK having a total replacement is around 70 years. The procedure is often delayed, to reduce the chance of needing revision surgery at a later date.

This study shows that at least 80% of total replacements last for 25 years. This could mean that people are offered surgery younger.

Ideally, outcome data from a UK registry could include reporting on the situation here along with functional outcomes and satisfaction. This study was unable to look at problems that were not severe enough to lead to revision surgery.

Citation and Funding

Evans JT, Walker R, Evans W et al. 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. Lancet. 2019;393:655-63.

This study was supported by the NIHR Biomedical Research Centre at the University Hospitals Bristol NHS Foundation Trust and the University of Bristol.

Bibliography

BOA and RCS. Commissioning guide: painful osteoarthritis of the knee. London: Royal College of Surgeons; 2017.

National Joint Registry. Knees – all procedures. London: National Joint Registry UK; 2018.

National Joint Registry. Public and patient guide to the NJR’s 14th annual report 2017: knee replacement edition. London: Healthcare Quality Improvement Partnership; February 2018.

NHS website. Knee replacement. London: Department of Health and Social Care; 2016.

Why was this study needed?

Knee replacement surgery is a routine operation to replace a worn or damaged knee joint with an artificial one. The most common reason for needing surgery is osteoarthritis. Total knee replacement is where both sides of the knee joint are replaced. Unicompartmental knee replacement involves just one side of the knee joint being replaced. A variety of components and methods of fixing can be used.

In 2017 there were 106,334 knee replacement procedures carried out in England, Wales and Northern Ireland. The average age of patients was 69 years. There were also 6,502 knee revision procedures, where people needed a second operation. Further surgery on elderly patients should be avoided if possible, so it is important to know how long a knee replacement can be expected to last. Research to date only gives estimates for 15 and 20 years. This study looked at longer-term data.

What did this study do?

This study was made up of a systematic review and meta-analysis of published case series, and a meta-analysis of data from national joint registries. The authors found 33 case series, with a total of 7,232 knee replacements. Twenty-six case series looked at total replacement, while seven reported survival of unicompartmental replacement. Data from the Australian and Finnish national registries were used, with a total of 299,291 total replacements, and 7,714 unicompartmental.

The quality of the published case series was low. And only the Finnish registry had outcomes data at 20 and 25 years.

What did it find?

Data from the national registries provided the most reliable results:

  • For total knee replacements, 93.0% were still intact at 15 years (95% CI 92.8 to 93.1; Australian and Finnish registries with 299,291 replacements). At 20 years, 90.1% of replacements had survived (95% CI 89.7 to 90.4; Finnish registry with 88,532 replacements). 82.3% of replacements were still intact at 25 years (95% CI 81.3 to 83.2; Finnish registry with 76,651 replacements).
  • For unicompartmental replacements, 76.5% were still intact at 15 years (95% CI 75.2 to 77.7; Finnish registry with 7,714 procedures). At 20 years, 71.6% had survived (95% CI 69.6 to 73.6; Finnish registry with 3,935 replacements). 69.8% were still intact at 25 years (95% CI 67.6 to 72.1; Finnish registry with 3,935 replacements).

What does current guidance say on this issue?

The British Orthopaedic Association and Royal College of Surgeons published a commissioning guide for painful osteoarthritis of the knee in 2017.

It says that total knee replacements should only be considered for patients whose pain has not been adequately controlled by three months of non-surgical management (based on NICE guidance for managing osteoarthritis).

It states that joint survival is 95% at seven years. It also says that unicompartmental knee replacement has a lower joint survival than total replacement.

What are the implications?

This study provides evidence that knee replacement surgery has better long-term outcomes than was previously thought. The average age of someone in the UK having a total replacement is around 70 years. The procedure is often delayed, to reduce the chance of needing revision surgery at a later date.

This study shows that at least 80% of total replacements last for 25 years. This could mean that people are offered surgery younger.

Ideally, outcome data from a UK registry could include reporting on the situation here along with functional outcomes and satisfaction. This study was unable to look at problems that were not severe enough to lead to revision surgery.

Citation and Funding

Evans JT, Walker R, Evans W et al. 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. Lancet. 2019;393:655-63.

This study was supported by the NIHR Biomedical Research Centre at the University Hospitals Bristol NHS Foundation Trust and the University of Bristol.

Bibliography

BOA and RCS. Commissioning guide: painful osteoarthritis of the knee. London: Royal College of Surgeons; 2017.

National Joint Registry. Knees – all procedures. London: National Joint Registry UK; 2018.

National Joint Registry. Public and patient guide to the NJR’s 14th annual report 2017: knee replacement edition. London: Healthcare Quality Improvement Partnership; February 2018.

NHS website. Knee replacement. London: Department of Health and Social Care; 2016.

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

Published on 21 February 2019

Evans, J. T.,Walker, R. W.,Evans, J. P.,Blom, A. W.,Sayers, A.,Whitehouse, M. R.

Lancet Volume 393 Issue 10172 , 2019

BACKGROUND: Knee replacements are the mainstay of treatment for end-stage osteoarthritis and are effective. Given time, all knee replacements will fail and knowing when this failure might happen is important. We aimed to establish how long a knee replacement lasts. METHODS: In this systematic review and meta-analysis, we searched MEDLINE and Embase for case series and cohort studies published from database inception until July 21, 2018. Articles reporting 15 year or greater survival of primary total knee replacement (TKR), unicondylar knee replacement (UKR), and patellofemoral replacements in patients with osteoarthritis were included. Articles that reviewed specifically complex primary surgeries or revisions were excluded. Survival and implant data were extracted, with all-cause survival of the knee replacement construct being the primary outcome. We also reviewed national joint replacement registry reports and extracted the data to be analysed separately. In the meta-analysis, we weighted each series and calculated a pooled survival estimate for each data source at 15 years, 20 years, and 25 years, using a fixed-effects model. This study is registered with PROSPERO, number CRD42018105188. FINDINGS: From 4363 references found by our initial search, we identified 33 case series in 30 eligible articles, which reported all-cause survival for 6490 TKRs (26 case series) and 742 UKRs (seven case series). No case series reporting on patellofemoral replacements met our inclusion criteria, and no case series reported 25 year survival for TKR. The estimated 25 year survival for UKR (based on one case series) was 72.0% (95% CI 58.0-95.0). Registries contributed 299 291 TKRs (47 series) and 7714 UKRs (five series). The pooled registry 25 year survival of TKRs (14 registries) was 82.3% (95% CI 81.3-83.2) and of UKRs (four registries) was 69.8% (67.6-72.1). INTERPRETATION: Our pooled registry data, which we believe to be more accurate than the case series data, shows that approximately 82% of TKRs last 25 years and 70% of UKRs last 25 years. These findings will be of use to patients and health-care providers; further information is required to predict exactly how long specific knee replacements will last. FUNDING: The National Joint Registry for England, Wales, Northern Ireland, and Isle of Man and the Royal College of Surgeons of England.

Expert commentary

This article makes for a very good headline. It brings together data from various sources and lets commissioners and patients know that knee replacement is a very durable intervention.

However, the data behind it lacks depth, and the key outcomes of function and satisfaction are not captured. The authors have extrapolated from country to country and to a greater timespan than that for which they have robust data. The main issue to be wary of is that their endpoint is revision. An unhappy patient with an unsuccessful operation who does not have a further knee replacement operation is counted as a success.

The success of a knee replacement will depend on multiple patient, surgical and implant-related variables – each patient still needs to be considered carefully as an individual. Patients should be optimistic about these results but will still need to engage carefully with their carers in order for them to have realistic expectations.

Fares S Haddad, Professor of Orthopaedic and Sports Surgery; Consultant Orthopaedic Surgeon, University College Hospital, London

The commentator declares no conflicting interests