Patients Receiving A Primary Unicompartmental Knee Replacement Have A Higher Risk Of Revision But A Lower Risk Of Mortality Than Predicted Had They Received A Total Knee Replacement: Data From The National Joint Registry for England, Wales, Northern Ireland and the Isle of Man

Linda P Hunt, Ashley W Blom, Gulraj Matharu*, Setor K Kunutsor, Andrew D Beswick, J Mark Wilkinson, Michael R Whitehouse

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

Abstract

Background
To determine unicompartmental (UKR) and total knee replacement (TKR) revision rates, compare UKR revision rates with what they would have been had they received TKR instead, subsequent re-revision and 90-day mortality rates.

Methods
Using National Joint Registry data, we estimated UKR and TKR revision and mortality rates. Flexible Parametric Survival modelling (FPM) was used to model failure in TKR and make estimates for UKR. Kaplan-Meier estimates were used to compare cumulative re-revision for revised UKRs and TKRs.

Results
10-year UKR revision rates were 2.5-times higher than expected from TKR, equivalent to 70 excess revisions/1,000 cases within 10-years (5,861 excess revisions in this cohort). Revision rates were 2.5 times higher for the highest quartile volume UKR surgeons compared to the same quartile for TKR, and 3.9 times higher for the lowest quartiles respectively. Re-revision rates of revised TKRs (10-years=17.5%; 95%CI=16.4,18.7) were similar to revised UKRs (15.2%; 95%CI=13.4,17.1) and higher than revision rates following primary TKR (3.3%, 95%CI=3.1,3.5). 90-day mortality rates were lower after UKR compared with TKR (0.08% vs. 0.33%) and lower than predicted had UKR patients received a TKR (0.18%), equivalent to 1 fewer death per 1,000 cases.

Conclusions
UKR revision rates were substantially higher than TKR even when demographics and caseload differences were accounted for, however fewer deaths occur after UKR. This should be considered when forming treatment guidelines and commissioning services. Re-revision rates were similar between revised UKRs and TKRs, but considerably higher than for primary TKR, therefore UKR cannot be considered an intermediate procedure.
Original languageEnglish
Pages (from-to)471-477.e6
Number of pages7
JournalJournal of Arthroplasty
Volume36
Issue number2
Early online date7 Sep 2020
DOIs
Publication statusPublished - 1 Feb 2021

Keywords

  • outcomes
  • mortality
  • revision rates
  • total knee replacement
  • unicompartmental knee

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