Joint replacement involves surgery to replace the ends of bones in a damaged joint and create new joint surfaces. In knee replacement surgery, the ends of the damaged thigh and lower leg (shin) bones and usually the kneecap are capped with artificial surfaces lined with metal and plastic. Usually, doctors replace the entire surface at the ends of the thigh and lower leg bones, and secure knee joint components to the bones with cement.
Doctors recommend joint replacement surgery when knee pain and loss of function become severe and when medicines and other treatments no longer relieve pain. Your doctor will use X-rays to look at the bones and cartilage in your knee to see whether they are damaged and to make sure that the pain isn't coming from somewhere else.