 Knee pain and stiffness is a common problem which can sometimes be improved by inserting a replacement knee joint. An anaesthetist is a doctor who specialises in looking after patients undergoing surgery, and there are a variety of different anaesthetics which can be used for knee replacement surgery. These include general anaesthesia going to sleep, and spinal or epidural anaesthesia where pain killers are injected into the back, resulting in temporarily numb legs. Pain killers can also be injected around the nerves which supply the leg, or around the site of the operation itself, combined with general or spinal anaesthesia if required. 