A shiny new metal knee! This image shows an intraoperative view of a total knee arthroplasty or replacement. Notice the femoral and tibial components and the plastic spacer!! Knee replacement, or knee arthroplasty, is a common operation done to relieve the pain and disability from degenerative arthritis, most commonly osteoarthritis, but other arthritides as well. The surgery consists of replacing the diseased and painful joint surfaces of the knee with metal and plastic components shaped to allow continued motion of the knee. This, in fact, is considered a major surgery and involves exposure of the front of the knee, with detachment of part of the quadriceps muscle (specifically the vastus medialis) from the kneecap. The kneecap is displaced to one side of the joint allowing exposure of the distal end of the thighbone (femur) and the proximal end of the shinbone (tibia). The ends of these bones are then accurately cut to shape using cutting guides oriented to the long axis of the bones. The cartilages and the anterior cruciate ligament are removed, but the collateral ligaments are preserved. Metal components are then impacted onto the bone or fixed using poly methyl methacrylate cement. A round ended implant is used for the femur, mimicking the natural shape of the bone. A flattened or slightly dished high density polyethylene surface is then inserted onto the tibial component so that the weight is transferred metal to plastic not metal to metal. During the operation any deformities must be corrected, and the ligaments balanced so that the knee has a good range of movement and is stable. In some cases the joint surface of the kneecap is also removed and replaced by a polyethylene button cemented to the kneecap.
Can the patient bear weight after the operation or need to use walking stick and wheelchair to ambulate for a certain period?