Knee replacement is a type of surgery in which artificial parts are used to replace a damaged knee joint, and minimally invasive knee replacement involves smaller incisions than the ones used in conventional surgery. Both total knee replacement and partial knee replacement may be carried out using minimally invasive surgery, or MIS, techniques. In this kind of knee replacement surgery, there is less damage to muscles around the knee than with traditional methods. Compared with traditional knee replacement surgery, recovery is likely to be quicker, with less pain and scarring, but there may be a greater risk of other complications, and research into minimally invasive knee replacement is still ongoing.
The most frequently carried out type of minimally invasive knee replacement surgery involves a total replacement of the knee joint. There are a number of causes of knee damage, but the most common is osteoarthritis. In osteoarthritis, the cartilage that protects the surfaces of the bones inside the knee joint becomes worn over time. People with severe osteoarthritis that causes constant pain may be considered for minimally invasive knee replacement as long as they are not excessively overweight, the bones around the knee joint are strong and they have not had knee surgery before.
During minimally invasive knee replacement, the surgeon uses special tools which allow the operation to be carried out through small incisions. The group of muscles above the knee, known as the quadriceps, are attached to the kneecap through a band of tissue known as the quadriceps tendon. In traditional surgery, the tendon is cut and the kneecap is turned over to get to the knee joint, but with the minimally invasive method only a small cut is made and the kneecap is moved aside. The reduced muscle damage allows patients to recover faster and leave the hospital sooner.
In one type of minimally invasive knee replacement, known as quadriceps-sparing, the quadriceps tendon is not cut at all but is lifted up to allow access to the knee joint. X-ray images may be required during the procedure to ensure accuracy, and special knee implants may be used. Sparing the quadriceps tendon is thought to enable patients to walk sooner and reduce pain following surgery.
After minimally invasive knee replacement, patients are usually able to leave their beds the same day or the day after surgery. Painkillers are taken, together with anticoagulant drugs to prevent blood clotting in the legs. Although the surgery is relatively new and still being evaluated, it is thought that knees replaced using minimally invasive methods should last for decades, as long as patients follow their surgeons' advice.