Title: Surgery Or REstraint for the unexplained painful knee replacement (the SORE KNEE Study): Patient, Clinical and Cost Effectiveness Considerations
Funder: Department of Health and Social Care

Abstract: This research will answer the question: 'What are the important patient, clinical and health economic considerations when deciding whether to manage patients with refractory, unexplained pain after knee replacement with revision surgery?'. BackgroundOver 6000 revision knee replacements are performed each year in the UK, at a cost of 90 million. Revision surgery is complex, technically demanding and carries significant morbidity and mortality. This burden of disease is projected to double by 2030 as the population ages. Most revision procedures are performed to address a specific cause of failure of the joint replacement (for example, infection or fracture). However, 15% of procedures are for unexplained pain where many patients do not experience improvement in pain or quality of life following surgery. These surgeries put patients at risk, with little chance of improvement and, in many cases, may be unnecessary. The need to evaluate the value and efficacy of surgery underpins this research theme. Research objectives and methods Systematic review to summarise patient-relevant outcomes following revision knee replacement for unexplained pain.Patient-reported outcome measures (PROMs), re-operation and acquired comorbidity after revision knee replacement for unexplained pain will be summarised by systematic review of the literature. Epidemiological analysis of temporal trends and geographic variation in national delivery of revision knee replacement surgery for unexplained pain.70,000 revision knee replacements will be analysed from linked National Joint Registry (NJR) and Hospital Episode Statistics (HES) datasets. Crude and direct-standardised rates of revision knee replacement for unexplained pain will be compared to other surgical indications. A qualitative research study exploring patient and surgeon considerations for selecting revision knee replacement as a management option for unexplained painSemi-structured interviews will be performed with 12-15 patients and 5 surgeons from the painful knee clinic at a tertiary centre. Sampling will continue until thematic saturation. The interview schedule will explore: (i) the decision to choose surgery, and (ii) the most important postoperative outcomes. Analysis of PROMs to produce estimates of meaningful change in pain following revision knee replacement for unexplained pain.PROM data for 2000 patients undergoing revision knee replacement for unexplained pain will be analysed. I will produce currently unknown anchor-based estimates for the minimal important change (MIC), which will identify clinically-relevant changes following revision surgery. Cost-utility analysis of revision knee replacement to investigate the cost-effectiveness of surgery for unexplained pain.Ultimately, I will use the information derived above and national data to report outcomes following revision knee replacement for unexplained pain and to calculate cost-effectiveness compared to no surgery. Anticipated impact and disseminationThis proposal is a collaboration with patients that will address the clinical dilemma of whether surgery should be used to treat unexplained pain after knee replacement. It will identify outcomes that are important to patients and present these so they can be used for shared decision making. It may identify surgeries that could be avoided, with potential annual healthcare savings of 10 million.

Lay abstract: BackgroundKnee replacement implants are designed to last a long time, but do not last forever. A revision knee replacement is a procedure to replace an implant that is no longer functioning correctly. More than 6000 revision knee replacements are performed each year in the UK, at a cost of 90 million. Revision surgery is complex, technically-demanding and high-risk. However, at least one-in-three patients do not benefit from surgery. Patients with unexplained pain experience some of the poorest outcomes and some patients may be undergoing unnecessary surgery that puts them at significant risk. The aim of this proposal is to better understand and improve surgical care for this group.Patient and Public Involvement (PPI)I have chosen my research questions based on a recent James Lind Alliance Priority Setting Partnership: 'How should we measure the outcomes following revision knee surgery in a way that is meaningful to patients, and is surgery cost effective?'Key Questions & Study Designs What is already known about patient-relevant outcomes following revision knee replacement for unexplained pain?I will systematically review the literature to identify studies with clinical outcomes that patients have recognised to be important. I will summarise and present these outcomes. How common is revision knee surgery for unexplained pain? How has practice changed over the past decade? Does treatment depend on where you live or which surgeon is treating you?I have recently obtained permission to analyse four national healthcare databases, which include around 70,000 revision knee replacement procedures. I will estimate the number of patients undergoing revision knee replacement each year, and show how this has changed over time and whether treatment differs depending on where in the country it is delivered. Why do patients and surgeons choose revision knee replacement to treat unexplained pain? Which outcomes are most important following surgery?This will be a qualitative research study, where I interview patients and surgeons. The main purpose is to gain a deeper understanding of the themes underpinning the decision to choose revision surgery as a treatment for unexplained pain. What is a meaningful change in pain following revision knee replacement for unexplained pain?I will analyse the responses of more than 2,000 patients who have provided feedback on revision knee surgery for unexplained pain. I will estimate the change in pain required by the average patient to recognise a meaningful improvement following surgery. Is revision knee replacement for unexplained pain cost-effective?I will use national data to calculate the cost of revision knee replacement for unexplained pain. I will estimate the risks of complications from surgery (such as the need for a further procedure or return to hospital). I will evaluate how these costs are justified on the basis of improvements in the quality of life of patients.DisseminationMy findings will be shared with patients through freely-available online summaries, regular patient newsletters and via social media. I will disseminate widely to surgeons through conference abstracts, research papers and major orthopaedic associations.Intended BenefitsThis proposal will collaborate with patients to address the clinical dilemma of whether surgery should be used to treat unexplained pain after knee replacement. It will identify outcomes that are important to patients and present these so they can be used for shared decision making. It will identify surgeries that could be avoided, with potential healthcare savings of 10 million.

Research activity codes: 6.4 SURGERY;7.3 MANAGEMENT AND DECISION MAKING
Health categories: MUSCULOSKELETAL