A knee transplant, or a total knee arthroplasty (TKA) involves removing the natural, damaged knee, and replacing it with a mechanical implant that will mimic the action of the natural knee.
Literally, the surgeon removes the knee bone and cartilage, the tissue that holds the muscle to bone. This is replaced by the implant of metal and plastic.
There are different types of implants a surgeon can use. Some implants are cemented; they are fixed to the bone. Others are fit into the knee area and the bone around the knee grows around it holding it into position.