Skip to main content Skip to navigation


Key Information

Title: Robotic Arthroplasty: A Clinical and cost Effectiveness Randomised controlled trial (RACER)

Chief Investigators: Mr Andrew Metcalfe and Professor Edward Davis


Knee arthritis is a painful condition which can limit people’s activities. When knee arthritis is very bad, it can be treated with a knee replacement. These operations are often very successful at reducing pain and improving the amount of activity someone can do. They can be painful in the few weeks after the operation, and many people still have some knee symptoms, even some time after surgery.

Knee replacements have for many years been put in by surgeons using their experience and skill, with a standard set of instruments. However, some surgeons have started using a robotic arm to help them perform a knee replacement. The robotic arm is held by the surgeon during the operation and the surgeon always remains in control. The robot helps move the instruments into the correct position by sensing the position of the leg.
Those who believe that standard instruments are better think that the operation is quicker and simpler without the robot. They argue that they can make decisions and cut the bone with the same amount of precision and without the added expense of a robot. Whereas those who believe the robot is better think it makes them more precise, and that they can get a better result using the guidance provided by the robot.

No one yet knows if using the robot to help perform a knee replacement is any better or worse than performing a knee replacement with standard instruments. Therefore, this study will look at which operation is best at improving the way the knee feels after surgery. The study will also find out which operation results in less pain in the first few days after surgery, and which gives better quality of life in the long-term. The researchers will also study whether the use of the robot is worth the additional cost.

Who can participate?

People with knee osteoarthritis who are due to undergo total knee replacement.

Sample size:



Participants will be in the study for two years, although we will contact them at five and 10 years after the operation as well.

Sponsor: University of Warwick/ University Hospitals Coventry and Warwickshire (UHCW)

Funder: HTA programme, National Institute for Health Research

Registration Number: ISRCTN27624068 | IRAS 278357

Contact us:

Trial Manager:
Johnny Guck

Information for Participants - Main Study

Information or Participants - Learning Effects Study

Information for Researchers

Surgeon Training

Trial Documents

Trial Updates