In the final stages, when pain is severe and function is markedly diminished, some form of knee replacement will be necessary to restore function. There are several types and brands of implants available, from 1/3 knee replacement to 2/3 to a full replacement. Some can be inserted through a minimally invasive approach. Most implants can also be inserted with the aids of computers to ensure a more consistent placement of components. The surgery takes about 1 to 2 hours and is done under a general or spinal anaesthesia. With current pain control techniques, most patients experience soreness rather than severe pain. Most patients can begin walking the next day and can usually go home from the 3rd day onwards. Partial knee replacement patients can begin walking on the same day and can be discharged on the same day. Most implants will last 10-20 years, depending on the amount if use and the weight of the patient. With the newer implants, it is hoped that not only will they last longer or even a lifetime, but allow patients to engage in moderately intense sports.