Total versus partial knee replacement in patients with medial compartment knee osteoarthritis: the TOPKAT RCT

David J Beard* (Corresponding Author), Loretta J Davies, Jonathan A Cook, Graeme MacLennan, Andrew Price, Seamus Kent, Jemma Hudson, Andrew Carr, Jose Leal, Helen Campbell, Ray Fitzpatrick, Nigel Arden, David Murray, Marion K Campbell

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

22 Citations (Scopus)
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BACKGROUND: Late-stage medial compartment knee osteoarthritis can be treated using total knee replacement or partial (unicompartmental) knee replacement. There is high variation in treatment choice and insufficient evidence to guide selection.

OBJECTIVE: To assess the clinical effectiveness and cost-effectiveness of partial knee replacement compared with total knee replacement in patients with medial compartment knee osteoarthritis. The findings are intended to guide surgical decision-making for patients, surgeons and health-care providers.

DESIGN: This was a randomised, multicentre, pragmatic comparative effectiveness trial that included an expertise component. The target sample size was 500 patients. A web-based randomisation system was used to allocate treatments.

SETTING: Twenty-seven NHS hospitals (68 surgeons).

PARTICIPANTS: Patients with medial compartment knee osteoarthritis.

INTERVENTIONS: The trial compared the overall management strategy of partial knee replacement treatment with total knee replacement treatment. No specified brand or subtype of implant was investigated.

MAIN OUTCOME MEASURES: The Oxford Knee Score at 5 years was the primary end point. Secondary outcomes included activity scores, global health measures, transition items, patient satisfaction (Lund Score) and complications (including reoperation, revision and composite 'failure' - defined by minimal Oxford Knee Score improvement and/or reoperation). Cost-effectiveness was also assessed.

RESULTS: A total of 528 patients were randomised (partial knee replacement, n = 264; total knee replacement, n = 264). The follow-up primary outcome response rate at 5 years was 88% and both operations had good outcomes. There was no significant difference between groups in mean Oxford Knee Score at 5 years (difference 1.04, 95% confidence interval -0.42 to 2.50). An area under the curve analysis of the Oxford Knee Score at 5 years showed benefit in favour of partial knee replacement over total knee replacement, but the difference was within the minimal clinically important difference [mean 36.6 (standard deviation 8.3) (n = 233), mean 35.1 (standard deviation 9.1) (n = 231), respectively]. Secondary outcome measures showed consistent patterns of benefit in the direction of partial knee replacement compared with total knee replacement although most differences were small and non-significant. Patient-reported improvement (transition) and reflection (would you have the operation again?) showed statistically significant superiority for partial knee replacement only, but both of these variables could be influenced by the lack of blinding. The frequency of reoperation (including revision) by treatment received was similar for both groups: 22 out of 245 for partial knee replacement and 28 out of 269 for total knee replacement patients. Revision rates at 5 years were 10 out of 245 for partial knee replacement and 8 out of 269 for total knee replacement. There were 28 'failures' of partial knee replacement and 38 'failures' of total knee replacement (as defined by composite outcome). Beyond 1 year, partial knee replacement was cost-effective compared with total knee replacement, being associated with greater health benefits (measured using quality-adjusted life-years) and lower health-care costs, reflecting lower costs of the index surgery and subsequent health-care use.

LIMITATIONS: It was not possible to blind patients in this study and there was some non-compliance with the allocated treatment interventions. Surgeons providing partial knee replacement were relatively experienced with the procedure.

CONCLUSIONS: Both total knee replacement and partial knee replacement are effective, offer similar clinical outcomes and have similar reoperation and complication rates. Some patient-reported measures of treatment approval were significantly higher for partial knee replacement than for total knee replacement. Partial knee replacement was more cost-effective (more effective and cost saving) than total knee replacement at 5 years.

FUTURE WORK: Further (10-year) follow-up is in progress to assess the longer-term stability of these findings.

TRIAL REGISTRATION: Current Controlled Trials ISRCTN03013488 and NCT01352247.

FUNDING: This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 24, No. 20. See the NIHR Journals Library website for further project information.

Original languageEnglish
Pages (from-to)1-98
Number of pages98
JournalHealth technology assessment (Winchester, England)
Issue number20
Publication statusPublished - 31 May 2020

Bibliographical note

Article history
The research reported in this issue of the journal was funded by the HTA programme as project number 08/14/08. The contractual start date was in January 2010. The draft report began editorial review in February 2019 and was accepted for publication in October 2019. The authors have been wholly responsible for all data collection, analysis and interpretation, and for writing up their work. The HTA editors and publisher have tried to ensure the accuracy of the authors’ report and would like to thank the reviewers for their constructive comments on the draft document. However, they do not accept liability for damages or losses arising from material published in this report.


TOPKAT study group

Chief investigator
David Beard.

Trial co-investigators
Nigel Arden (Oxford), Helen Campbell (Oxford), Marion Campbell (Aberdeen), Andrew Carr (Oxford), Jonathan Cook (Aberdeen then Oxford), Helen Doll (Oxford), Ray Fitzpatrick (Oxford), David Murray (Oxford) and Andrew Price (Oxford).

Trial management
Mayret Castillo (until 2011), Cushla Cooper, Loretta Davies, Anne Duncan (until 2017), Gordon Fernie, Sophie Halpin (until 2015) and Alison McDonald.

Trial administration
Katie Chegwin, Jiyang Li (until 2018), Elena Rabaiotti (until 2013), Sandra Regan (until 2012) and Victoria Stalker (until 2014).

Data management
Diana Collins (until 2013), Janice Cruden, Akiko Greshon, Kay Holland and Beverley Smith (until 2017).

Database/programming management
Gladys McPherson.

Trial statisticians
Charles Boachie (until 2013), Jemma Hudson and Graeme MacLennan.

Health economists
Helen Campbell (until 2015), Francesco Fusco (until 2018), Seamus Kent and Jose Leal.

We would also like to thank Hannah Wilson (DPhil student, University of Oxford) for her help with the update to the literature search.
Research teams

We are grateful to the participants and research teams at collaborating hospital sites:
Aneurin Bevan University Health Board, Royal Gwent Hospital

Ruth Jenkins, Mark Lewis [principal investigator (PI)] and Witek Mintowt-Czyz.
Belfast Health and Social Care Trust, Musgrove Park Hospital, Belfast

David Beverland (PI), Leeann Bryce, Julie Catney, Ian Dobie, Emer Doran and Seamus O’Brien.
Chesterfield Royal Hospital NHS Foundation Trust

Fazal Ali, Heather Cripps, Amanda Whileman, Phil Williams (PI) and Julie Toms.
County Durham and Darlington NHS Foundation Trust

Ellen Brown, Gillian Horner, Andrew Jennings (PI) and Glynis Rose.
East Lancashire Hospitals NHS Trust, Royal Blackburn Hospital

Frances Bamford, Wendy Goddard, Hans Marynissen (PI), Haleh Peel and Lyndsey Richards.
Great Western Hospitals NHS Foundation Trust, Swindon

Amanda Bell, Sunny Deo, Sarah Grayland, David Hollinghurst, Suzannah Pegler, Venkat Satish (PI) and Claire Woodruffe.
Harrogate and District NHS Foundation Trust, Harrogate

Nick London (PI), David Duffy, Caroline Bennett and James Featherstone.
Hull and East Yorkshire Hospitals NHS Trust

Joss Cook, Kim Dearnley, Nagarajan Muthukumar (PI), Laura Onuoha and Sarah Wilson.
Maidstone and Tunbridge Wells NHS Trust, Medway

Sandhu Banher, Eunice Emeakaroha, Jamie Horohan, Sunil Jain (PI) and Susan Thompson.
Mid Yorkshire Hospitals NHS Trust

Sarah Buckley, Aaron Ng (PI), Ajit Shetty and Karen Simeson.
Milton Keynes University Hospital NHS Foundation Trust

Julian Flynn, Meryl Newsom, Cheryl Padilla-Harris and Oliver Pearce (PI).
NHS Grampian, Woodend Hospital, Aberdeen

James Bidwell (PI), Alison Innes, Winifred Culley and Bill Ledingham and Janis Stephen.
North Bristol NHS Trust

Rachel Bray, Hywel Davies, Debbie Delgado, Jonathan Eldridge, Leigh Morrison, James Murray (PI), Andrew Porteous and James Robinson.
North Cumbria University Hospitals NHS Trust, Carlisle

Matt Dawson (PI), Raj Dharmarajan, David Elson, Will Hage, Nicci Kelsall and Mike Orr.
North Tees and Hartlepool NHS Foundation Trust, Stockton-On-Tees

Jackie Grosvenor, SS Maheswaran (PI), Claire McCue, Hemanth Venkatesh, Michelle Wild and Deborah Wilson.
Oxford University Hospitals NHS Trust, Nuffield Orthopaedic Centre

Chris Dodd, William Jackson (PI), Pam Lovegrove, David Murray, Jennifer Piper and Andrew Price.
Royal United Hospitals Bath NHS Foundation Trust, Bath

Neil Bradbury, Lucy Clark, Stefanie Duncan, Genevieve Simpson and Allister Trezies (PI).
Sherwood Forest Hospitals NHS Foundation Trust, Kings Mill Hospital, Sutton in Ashfield

Vikram Desai (PI), Cheryl Heeley, Kramer Guy and Rosalyn Jackson.
South Devon Healthcare NHS Foundation Trust, Torbay

Alan Hall, Gordon Higgins (PI), Michael Hockings, David Isaac and Pauline Mercer.
Stockport NHS Foundation Trust, Stockport

Lindsey Barber, Helen Cochrane, Janette Curtis, Julie Grindey, David Johnson (PI), and Phil Turner.
The Hillingdon Hospitals NHS Trust

David Houlihan-Burne (PI), Briony Hill, Ron Langstaff and Mariam Nasseri.
The Ipswich Hospital NHS Trust, Ipswich

Mark Bowditch, Chris Martin, Steven Pryke, Bally Purewal, Chris Servant (PI), Sheeba Suresh and Claire Tricker.
University Hospitals of Leicester NHS Trust, Leicester

Robert Ashford, Manjit Attwal, Jeanette Bunga, Urjit Chatterji, Susan Cockburn, Colin Esler (PI), Steven Godsiff, Tim Green, Christina Haines and Subash Tandon.
University Hospitals of North Midlands NHS Trust, Stoke on Trent

Racquel Carpio, Sarah Griffiths, Natalie Grocott and Ian dos Remedios (PI).
University Hospital Southampton NHS Foundation Trust

David Barrett, Phil Chapman-Sheath, Caroline Grabau, Jane Moghul, William Tice (PI) and Catherine Trevithick.
United Lincolnshire Hospitals NHS Trust, Boston

Rajiv Deshmukh, Mandy Howes, Kimberley Netherton, Dipak Raj (PI) and Nikki Travis.
United Lincolnshire Hospitals NHS Trust, Lincoln

Mohammad Maqsood, Rebecca Norton, Farzana Rashid, Alison Raynor, Mark Rowsell and Karen Warner.

We would like to thank the external members of the TSC and DMC for their advice and support for the project.
Trial Steering Committee

Donna Dodwell as our patient representative, Simon Donell (chairperson) (University of East Anglia), Shawn Tavares (Royal Berkshire Hospital) and Jonathan Waite (South Warwickshire NHS Foundation Trust).
Data Monitoring Committee

Karen Barker (Oxford University Hospitals NHS Foundation Trust), Gordon Murray (chairperson) (University of Edinburgh) and Hamish Simpson (University of Edinburgh).

Independent review and interpretation of results
Professor David Torgerson (University of York).

Professor Chris Maher (University of Sydney).

Mr Peter Brownson (The Royal Liverpool and Broadgreen University Hospitals NHS Trust).

Professor Simon Donell (University of East Anglia, Norwich).

Mr Mark Mullins (Abertawe Bro Morgannwg University Health Board).

Professor Jane Blazeby (Bristol University).




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