2025 ISAKOS Congress in Munich, Germany

2025 ISAKOS Biennial Congress Paper


Ten Year Follow Up of a Multicentre Randomised Controlled Trial Assessing Clinical and Cost Effectiveness of Total Versus Partial Knee Replacement (TOPKAT)

David J. Beard, MA, MSc, DPhil, FBOA(Hon) FRCS(Hon), Prof., Oxford, Oxfordshire UNITED KINGDOM
Loretta Davies, DPhil, MSc, Oxford, Oxfordshire UNITED KINGDOM
Jonathan Cook, PhD, Oxford, Oxfordshire UNITED KINGDOM
Graeme MacLennan, MSc, Aberdeen UNITED KINGDOM
Jemma Hudson, PhD, Aberdeen UNITED KINGDOM
Andrew James Price, DPhil, FRCS(Orth), Oxford, Oxfordshire UNITED KINGDOM
Andrew Carr, Prof., Oxford, Oxfordshire UNITED KINGDOM
Matthew Little, PhD, Oxford UNITED KINGDOM
Jose Leal, PhD, Oxford, Oxfordshire UNITED KINGDOM
David Murray, FRCS(Orth), Headington, Oxford UNITED KINGDOM
Marion Campbell, PhD, Aberdeen UNITED KINGDOM
TOPKAT Study, Oxford, Oxfordshire UNITED KINGDOM

University of Oxford, Oxford, Oxon, UNITED KINGDOM

FDA Status Not Applicable

Summary

10 yr outcomes comparing TKR and PKR show similar clinical outcomes and similar re-operation/complication rates (including revision) but cost effectiveness remains in favour of PKR

Abstract

Background

Late-stage medial compartment knee osteoarthritis can be treated using Total Knee Replacement (TKR) or Partial (Unicompartmental) Replacement (PKR). There is high variation in treatment choice and insufficient evidence to guide selection.

Objective(s):
To assess the clinical and cost-effectiveness of PKR compared to TKR in patients with medial compartment knee osteoarthritis at long-term follow-up (10 years). The findings will guide treatment decision making for patients, surgeons and health care providers.

Method/Design:
Randomised, multi-centre, pragmatic comparative effectiveness trial including an expertise component. The target sample size was 500 patients. A web-based randomisation system was used to allocate treatment of patients with medial compartment knee osteoarthritis in 27 UK NHS hospitals (68 surgeons). The trial compared overall management strategy of PKR treatment with TKR treatment. No specified brand or sub type of implant was investigated. The Oxford Knee Score (OKS) at 10 years was the primary outcome for this analysis. Secondary outcomes included activity scores, global health measures, transition items, patient satisfaction [Lund Score] and complications, (including re-operation, revision and composite “failure” – defined by minimal OKS improvement and/or re-operation). Cost effectiveness was also assessed.

Results

528 patients were randomised (PKR n=264; TKR n=264). Follow-up primary outcome response rate at 10 years was 73%. Both operations provided good outcome. At 10 years the between-group estimates ruled out any worthwhile differences in mean OKS scores (diff 0.27; 95% CI -1.59, 2.13) or cumulatively over 10 years, Area Under the Curve analysis (diff 0.45; 95% CI -0.98, 1.88). There was no effect of surgeons grouping (expertise based or not), age, gender or baseline OKS. Secondary outcome measures consistently showed no differences between groups.

The frequency of re-operation (including revision) by treatment received was similar for both groups; 29/245 PKR and 31/269 TKR patients. Revision rates at 10 years were 15/245 for PKR (6.1 %) and 11/269 (4.1%) for TKR.

At 10 years, PKR was more cost-effective compared to TKR, being associated with greater health benefits (measured using quality adjusted life years PKR 6.16 v TKR 5.78) and lower healthcare costs.

Summary and Conclusions:
TOPKAT is the largest and longest RCT comparing PKR and TKR in the world. In a randomised and national health setting both TKR and PKR are effective, offer similar clinical outcomes and have similar re-operation and complication rates. The rate of revision for PKR was lower in the TOPKAT trial than the UK National Joint Registry. The small clinical differences in favour of PKR seen at 5 years are ameliorated at 10 years, although cost effectiveness remains in favour of PKR.

Trial registration: Current Controlled Trials ISRCTN03013488; ClinicalTrials.gov Identifier: NCT01352247
Funding: The study was funded by the UK National Institute of Health and Care Research (NIHR) Health Technology Assessment (HTA) Programme (project number 08/14/08)