Authors' objectives: Patients with symptoms of pain and restricted function related to knee osteoarthritis are typically offered a knee replacement. However, a proportion remain dissatisfied with their outcomes, and the failure risk is disproportionately higher in the young. Knee joint distraction may be an intervention to postpone the time to knee replacement in this patient population. The primary objective of the Knee Arthroplasty versus Joint Distraction Study for Osteoarthritis (KARDS) was to evaluate the effectiveness of knee joint distraction compared to knee replacement based on patient-reported pain 12 months post surgery using the Knee Injury and Osteoarthritis Outcomes Score pain score as the primary outcome.

Authors' results and conclusions: Twenty-four participants were randomised from a single centre between March 2021 and October 2022 with minimum 3-month safety follow-up post surgery. Eleven participants were randomised to knee joint distraction and 13 to knee replacement. Seventeen patients were male (71%), median age 60 (47–65) years. One patient withdrew due to being medically unfit for surgery and two received a different treatment than which they were randomised (one crossover from each arm). The median Knee Injury and Osteoarthritis Outcomes Score pain score in the knee joint distraction group improved from 38.9 (22–50) at baseline to 55.6 (0–100) at 12 months, corresponding scores in the knee replacement improved from 30.6 (6–36) to 75.0 (50–100). Adverse events were more common with knee joint distraction, pin site infection being the commonest complications (n = 4, 58%). As part of process evaluation, we conducted semistructured qualitative interviews with staff in secondary care and with study participants. Data were analysed using thematic content analysis. One overarching theme emerged: ‘An unexpected journey’, which encapsulates staff and participants’ experiences. Reduced research capacity and the suspension of elective surgery following the COVID-19 pandemic caused significant recruitment barriers. Despite early termination, KARDS demonstrated that patients were willing to be recruited to a trial investigating a novel treatment for knee osteoarthritis and the trial was feasible and implementable. The limited results indicated that the technique is safe with no safety concerns. Clinical and cost-effectiveness of knee joint distraction remains uncertain. The embedded KARDS process evaluation has provided helpful insights.

Authors' methods: KARDS was an open-label, two-arm individually randomised controlled non-inferiority trial with an embedded 12-month internal pilot phase and process evaluation to evaluate recruitment feasibility. A hybrid expertise design was used to account for surgeon expertise and potential lack of individual equipoise. The trial was closed to recruitment early following cessation of elective orthopaedic surgery secondary to COVID-19 pandemic. Descriptive statistics are reported. United Kingdom National Health Service Trusts. Adult patients aged

Project Status: Completed

URL for project: https://www.journalslibrary.nihr.ac.uk/programmes/hta/NIHR136104

Year Published: 2025

URL for published report: https://www.journalslibrary.nihr.ac.uk/hta/ANDK1124

URL for additional information: English

English language abstract: An English language summary is available

Publication Type: Full HTA

Country: England, United Kingdom

DOI: 10.3310/ANDK1124

Organisation Name: NIHR Health Technology Assessment programme

Contact Address: NIHR Journals Library, National Institute for Health and Care Research, Evaluation, Trials and Studies Coordinating Centre, Alpha House, University of Southampton Science Park, Southampton SO16 7NS, UK

Contact Name: journals.library@nihr.ac.uk

Contact Email: journals.library@nihr.ac.uk