How long do revised and multiply revised knee replacements last? A retrospective observational study of the National Joint Registry

Background Knee replacements are common and effective operations but patients that undergo this intervention are at risk of needing subsequent costly and often complex revision surgery with poorer outcomes than primary surgery. The treatment pathway over the life of the patient in terms of risk of revision and re-revisions is poorly described. We aim to provide detailed information on the longevity of revision surgery. Methods We did a retrospective observational registry-based study of the National Joint Registry in England and Wales, UK. Knee replacement revision procedures linked to a primary episode were included; duplicates, records with missing information, and records with an unknown sequence of revision procedures were not included. Kaplan-Meier estimates were used to determine the cumulative probability of revision and subsequent re-revisions following primary knee replacement. Analyses were stratified by age and gender, and the influence of time from first to second revision on the risk of further revision was explored. Findings Between April 1, 2003, and Dec 31, 2018, 33 292 revision knee replacements were linked with a primary episode. Revision rates of revision knee replacements were higher in males than females at 10 years (20.0% [95% CI 19.0-21.0] vs 14.8% [13.9-15.6]) and higher in younger patients at 10 years (females younger than 55 years 21.0% [18.6-23.5] vs females aged 75-79 years 8.3% [6.8-10.2]; males younger than 55 years 26.6% [23.9-29.5] vs males aged 75-79 years 13.6% [10.6-17.5]). 19.9% (18.3-21.5) of first revisions were revised again within 13 years, 20.7% (19.1-22.4) of second revisions were revised again within 5 years, and 20.7% (17.1-24.9) of third revisions were revised again within 3 years. A shorter time between revision episodes was associated with earlier subsequent revision. Interpretation Males and younger patients are at higher risk of multiple revisions. Patients who undergo a revision have a steadily increasing risk of further revision the more procedures they undergo, and each subsequent revision lasts for approximately half the time of the previous one. Although knee replacements are effective for improving pain and function and usually last a remarkably long time, if they are revised, successive revisions are progressively and markedly less successful. Copyright (C) 2021 The Author(s). Published by Elsevier Ltd.