During knee replacement surgery, damaged bone and cartilage is resurfaced with metal and plastic components. In unicompartmental knee replacement (also called "partial" knee replacement) only a portion of the knee is resurfaced. This procedure is an alternative to total knee replacement for patients whose disease is limited to just one area of the knee.

Because a partial knee replacement is done through a smaller incision, patients usually spend less time in the hospital and return to normal activities sooner than total knee replacement patients.