Osteoarthritis of the hip is a painful condition, when it becomes severe it can be treated with a total hip replacement. This is a very common and successful operation at reducing pain and disability for people with osteoarthritis of the hip. However, some people continue to experience pain and problems with their hip, even after having the operation.

Total hip replacements have been performed for many years by orthopaedic surgeons, who use their experience and expertise to replace the hip with a standard set of instruments. The surgeons are very familiar with these instruments and have learned how to use them to get the best results. This is the most common way of performing a total hip replacement.

In more recent years, some surgeons have started using a robotic arm to help them perform the total hip replacement operation. The robotic arm is held and controlled by the surgeon throughout the procedure. The robot arm is meant to help move the instruments into the correct position by sensing the position of the leg more accurately.

No one yet knows if using the robot to help perform a hip replacement is any better or worse than performing a hip replacement with standard instruments. Therefore, this study will look at which operation is best at improving the way the hip feels and functions 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.