Skip to content

Assessing the non-inferiority of prosthesis constructs used in total and unicondylar knee replacements using data from the National Joint Registry of England, Wales, Northern Ireland and the Isle of Man: A benchmarking study

Research output: Contribution to journalArticle (Academic Journal)

Original languageEnglish
Article numbere026736
Pages (from-to)e026736
Number of pages14
JournalBMJ Open
Issue number4
Early online date30 Apr 2019
DateAccepted/In press - 25 Mar 2019
DateE-pub ahead of print - 30 Apr 2019
DatePublished (current) - Apr 2019


Objectives: To investigate the relative performance of knee replacement constructs compared with the best performing construct and illustrate the substantial variability in performance. Design: A non-inferiority study. Setting: England and Wales. Participants: All primary total and unicondylar knee replacements performed and registered in the National Joint Registry between 1 April 2003 and 31 December 2016. Main outcome measures: Kaplan-Meier failure function for knee replacement constructs. Failure difference between best performing construct (the benchmark) and other constructs. Methods: Using a non-inferiority analysis, the performance of knee replacement constructs by brand were compared with the best performing construct. Construct failure was estimated using the 1-Kaplan Meier method, that is, an estimate of net failure. The difference in failure between the contemporary benchmark construct and all other constructs were tested. Results: Of the 449 different knee replacement constructs used, only 27 had ≥500 procedures at risk at 10 years postprimary, 18 of which were classified as inferior to the benchmark by at least 20% relative risk of failure. Two of these 18 were unicondylar constructs that were inferior by at least 100% relative risk. In men, aged 55-75 years, 12 of 27 (44%) constructs were inferior by at least 20% to the benchmark at 7 years postprimary. In women, aged 55-75 years, 8 of 32 (25%) constructs were inferior at 7 years postprimary. Very few constructs were classified as non-inferior to the contemporary benchmark. Conclusions: There are few knee replacement constructs that can be shown to be non-inferior to a contemporary benchmark. Unicondylar knee constructs have, almost universally, at least 100% worse revision outcomes compared with the best performing total knee replacement. These results will help to inform patients, clinicians and commissioners when considering knee replacement surgery.

Additional information

© Author(s) (or their employer(s)) 2019. Re-use permitted under CC BY. Published by BMJ.

    Structured keywords

  • Centre for Surgical Research

    Research areas

  • benchmarking, knee arthroplasty, medical devices, national joint registry, non-inferiority

Download statistics

No data available



  • Full-text PDF (final published version)

    Rights statement: This is the final published version of the article (version of record). It first appeared online via BMJ Publishing at . Please refer to any applicable terms of use of the publisher.

    Final published version, 2.12 MB, PDF document

    Licence: CC BY


View research connections

Related faculties, schools or groups