Title: The clinical and cost-effectiveness of elective primary total knee replacement with PAtellar Resurfacing compared to selective patellar resurfacing. A pragmatic multicentre randomised controlled Trial with blinding (PART)
Funder: Department of Health and Social Care

Abstract: Background & Aims_x000D_ Controlling pain and improving mobility in the long-term after knee replacement surgery has been highlighted as a research priority by patients. Knee replacement is common (109,000/year in the UK) and is performed to help patients with pain from disabling arthritis. There are two ways to carry out this surgery. In about two thirds of knee replacements, the kneecap (patella) is unaltered during the operation. In the remaining third of operations the surgeon attaches a separate artificial implant to the back of the kneecap, which may help reduce further wear or pain. This is known as resurfacing the kneecap. Resurfacing is an extra step in the operation which takes time and sometimes causes problems later on. Not resurfacing can cause long-term knee pain, and further surgery may be needed, resulting in risks for patients and expense to the NHS. Recent national guidelines compared resurfacing the kneecap in all patients with never resurfacing the kneecap and concluded that in the long-term resurfacing in all cases was better than never resurfacing._x000D_ _x000D_ However, many surgeons make an individual choice about whether to resurface the kneecap, based on factors such as pain and the condition of the kneecap. We call this selective resurfacing. The National Institute for Health and Care Excellence (NICE) highlighted a need for research about whether selective resurfacing is better than always resurfacing during knee replacement._x000D_ _x000D_ This study will compare whether it is better if surgeons resurface every patient’s kneecap during knee replacement or if surgeons only resurface the kneecap when they believe it will lead to a better outcome. _x000D_ _x000D_ Design & Methods_x000D_ Our study will compare patients undergoing knee replacement who all have the kneecap resurfaced with those who have it selectively resurfaced. This will find out which strategy gives better outcomes for patients, and whether one is better value for money for the NHS. Over 4 years we will recruit 530 patients having knee replacement at 15 or more hospitals. They will be put into two equal groups. This will be done randomly to allow a fair comparison. All the patients in one group will have their kneecap resurfaced. In the other group the surgeon will decide during the operation whether or not to resurface the kneecap. All other aspects of care will be the same. Both groups will be followed for 1 year to monitor knee pain, mobility, quality of life, complications, further surgery and costs to the NHS and patients._x000D_ _x000D_ Patient & Public Involvement (PPI) & Dissemination_x000D_ This study has been developed with our musculoskeletal PPI group. Some members had undergone knee replacement, but none knew about patellar resurfacing, and whether or not they received it. Members thought our work would answer important research questions with clear and direct patient relevance and benefit, which could ultimately improve patient outcomes after knee surgery. The group considered the trial interventions, methods, outcome measures, and study conduct to be acceptable to patients. They also helped write the plain English summary and their input has informed the study design (e.g. assessing patient reported outcomes before 6 months). To ensure patient views are central to the research we will continue to work with our PPI group through regular meetings discussing design and management of the research, as well as how to share the findings with the public, health professionals and NHS trusts.

Lay abstract: BACKGROUND: Total knee replacement (TKR) is commonly used for treating severe arthritis, with over 100,000 performed annually in the UK. During TKR, surgeons can resurface the patella (replace the under surface of the kneecap with a plastic prosthesis) or leave the native patella to articulate with the femoral implant. Resurfacing the patella is initially more expensive (longer theatre time, higher implant cost, risk of additional post-operative complications), but in the long-term it can reduce the risk of on-going pain which can result in further surgery to resurface the patella._x000D_ _x000D_ NICE recommends always resurfacing the patella rather than never doing so. NICE did not find sufficient evidence on selective resurfacing (intraoperative decision based on the state of the patellar surface and the patients’ symptoms) to make a recommendation on that strategy, but did recommend specific research was conducted on this question. If effective, selective resurfacing could result in optimal individualised patient care._x000D_ _x000D_ AIM: To evaluate the clinical and cost-effectiveness of elective primary TKR with always patellar resurfacing compared to selective patellar resurfacing._x000D_ _x000D_ DESIGN: Patient and assessor-blinded multicentre, pragmatic two-group randomised superiority trial._x000D_ _x000D_ SETTING: NHS hospitals in England._x000D_ _x000D_ POPULATION: Adults having primary TKR for osteoarthritis._x000D_ _x000D_ EXCLUSION CRITERIA: Patellar thickness insufficient for resurfacing (checked intraoperatively). Primary TKR with the need for constrained implants._x000D_ _x000D_ INTERVENTIONS: Randomisation to always patellar resurfacing, or selective patellar resurfacing._x000D_ _x000D_ OUTCOME MEASURES: Primary: Oxford Knee Score (OKS) at 1 year, a validated patient reported outcome measure (PROM). Secondary: PROMs at 3 months, 6 months and 1 year, including the Knee Injury & Osteoarthritis Outcome Score, OKS, and EQ-5D-5L; postoperative complications, resource use and costs within 1 year._x000D_ _x000D_ SAMPLE SIZE: The OKS minimally clinically important difference is 4 points (standard deviation 10 points). A study of 530 patients (265/group) will provide 90% power with 5% statistical significance (2-sided) to detect this effect size allowing for 10% loss to follow-up, up to 40% resurfacing in the selective group, 5% not resurfacing in the always group and an 82% efficiency gain from repeated OKS at baseline, 3 months, 6 months and 1 year._x000D_ _x000D_ ANALYSIS: Primary statistical and economic analyses will be intention-to-treat and follow a pre-specified analysis plan. Results will be reported following CONSORT and CHEERS guidelines. We will estimate effectiveness and cost-effectiveness beyond the trial using modeling._x000D_ _x000D_ PROJECT TIMETABLE & RECRUITMENT RATE: Study duration 48 months: 6m set up, 24m recruitment (8m internal pilot, 16m main trial), 12m for patient follow-up, 6m analysis and report. Longer-term outcomes will be assessed with routinely collected data (subject to further funding). The study aims to recruit a mean 2.8 patients/centre/month._x000D_ _x000D_ ANTICIPATED IMPACT & DISSEMINATION: Results will be disseminated to researchers, healthcare professionals, the public, and stakeholders (commissioners, regulators and NICE) through open access peer-review publications, presentations, and other media. The trial will demonstrate if selective or always patellar resurfacing is the most clinically and cost-effective approach. This research has the potential to improve outcomes and prevent complications for people having primary TKR.

Research activity codes: 6.4 SURGERY
Health categories: MUSCULOSKELETAL