Title: Robotic Arthroplasty: a Clinical and cost Effectiveness Randomised controlled trial. (RACER)
Funder: Department of Health and Social Care

Abstract: What is the problem?_x000D_ _x000D_ Robotic systems are increasingly being used to help surgeons perform knee replacements. They are expensive, but we do not know if they provide any benefit for patients._x000D_ _x000D_ Over 100,000 knee replacements were done in the UK in 2017, costing the NHS over £550Million. Most knee replacements reduce the pain and disability caused by severe arthritis; but results are mixed, one in five people are unhappy with the outcome, or have pain as bad as it was before._x000D_ _x000D_ Better results are needed after knee replacement. Some small studies have found that surgeons are more precise and cut less tissue when using a robot to help perform knee replacement. This should make the replacements function better with less pain, and last longer._x000D_ _x000D_ Robotic knee replacement systems are used in a few NHS Trusts. They are very expensive. Using them routinely will cost the NHS many millions of pounds each year. If robotic systems improve patient outcomes or reduce complications this could be money well spent._x000D_ _x000D_ What are we trying to find out?_x000D_ _x000D_ We want to find out if total knee replacement performed with the help of a robot is better than using the standard technique. We will determine this using a questionnaire taken one year after surgery, and also on the balance between the cost of using the robot and the benefits it may have._x000D_ _x000D_ How are we going to do this?_x000D_ _x000D_ Our study will take place in five hospitals and will involve 332 people having a knee replacement. People will be approached in clinic or their pre-operative education class, so there is a lot of time to consider the study. Everyone taking part will have a CT scan so that a personalised computer plan can be made for the operation. There is a small radiation dose from this, but the risk from radiation in the study is low._x000D_ _x000D_ Before the operation, the surgeon will find out whether surgery will be with standard instruments, or with a robot. The decision will be made at random using an online system to ensure the decision is fair. The knee replacement will otherwise be the same for both groups. So that the robot can monitor exactly where their leg is, people will have two or four additional small cuts to the skin around their knee. Everyone in the study will have these extra skin cuts so they cannot tell which treatment they received, this prevents people being influenced by knowing whether they had the robot. Everyone in the study will receive the same instructions about exercises and recovering from a knee replacement._x000D_ _x000D_ We will ask participants about how much pain they have over the first three days after the operation. We will calculate blood loss, and record painkillers used, and how long people spend in hospital. Three, six and twelve months after surgery, we will ask participants about how their knee feels, how satisfied they are, how their general health is, and whether they have had any problems. We will also ask these questions two, five and ten years after the operation. We will do a CT scan of the knee and an x-ray of the whole leg three months after surgery to measure the exact position of the knee replacement._x000D_ _x000D_ We will use this information to decide whether robotic knee replacement or standard knee replacement give the best results for people undergoing knee replacements. We will also compare the costs to find out if robots provide good value for the NHS, or whether we should stop using them.

Lay abstract: Robotic systems are increasingly used to help surgeons perform knee replacements. They are expensive. We do not know if they provide any patient benefit, or if they are cost effective._x000D_ _x000D_ In 2017, 109,000 total knee replacements (TKRs) were done in the UK, at a cost of over £550M.(1-4) They substantially improve pain and function in many people. However up to 20% of patients are dissatisfied, 20% report pain as bad or worse than before the operation, and many have ongoing restrictions to activities of daily living.(5-7)_x000D_ _x000D_ Robotic systems aim to improve outcomes by helping the surgeon perform knee replacements with greater precision and less tissue damage than can be achieved with conventional instruments.(8) If robotic assisted surgery is beneficial, the costs could be offset by shorter inpatient stays and fewer complications. Their effectiveness compared with standard care is not known. Despite their high cost and lack of evidence of effectiveness, they are progressively being introduced into the NHS._x000D_ _x000D_ Our overarching aim is to determine whether robotic-assisted TKR is clinically and cost-effective when compared to TKR using conventional instruments._x000D_ _x000D_ We will perform a participant and assessor blind, pragmatic multi-centre RCT in 332 people with knee osteoarthritis. We will compare TKR done with the MAKO robot (Stryker, USA; the the most commonly used robotic-arm system worldwide, and until recently the only system available in the UK) to exactly the same type of TKR done with conventional instruments._x000D_ _x000D_ In addition to the normal TKR incision, two or four small additional incisions in the control group will blind participants and staff to the allocation. We will blind the operation note to prevent bias from staff such as physiotherapists. Everyone will have the same surgical planning before the operation using a CT scan. Everyone will receive the same post-operative rehabilitation programme._x000D_ _x000D_ Our primary outcome is the Forgotten Joint Score (FJS) at 12 months. This was developed specifically for assessing the results of joint replacement, there are good data on its metrics, and our PPI group approved of its use. We will also collect pain intensity over the first three post-operative days, estimated blood loss, in-patient opioid use, and time to discharge. PROMs at three, six and 12 months and two, five and ten years will include: FJS, Oxford Knee Score, Oxford Activity & Participation Questionnaire, PROMIS pain intensity scale, satisfaction, re-operations, adverse events, and resource use. We will also perform a very low dose CT and long-leg x-ray to check TKR alignment, three months post-operatively._x000D_ _x000D_ Patient involvement has been, and will be, integral throughout the study; including on the trial management team. An internal pilot study in the first five months will confirm the feasibility of the study. The main analysis will be on an intention-to-treat basis, using a generalised linear model including terms to adjust for allocation group, age, gender, BMI (>35) and primary compartment involved. A prospectively planned economic evaluation will be conducted from a NHS and personal social services perspective.(9)_x000D_ _x000D_ If we find that surgery done with a robot is clinically and cost-effective, it will improve the care of people undergoing knee replacement, the majority of whom do not currently have access to this technology. However, if it is ineffective the study will stop the widespread adoption of an expensive and unnecessary new technology.

Research activity codes: 6.4 SURGERY
Health categories: MUSCULOSKELETAL