What is a total knee replacement?

A total knee replacement is a surgical procedure whereby the diseased knee joint is replaced with artificial material. The knee is a hinge joint which provides motion at the point where the thigh meets the lower leg. The thigh bone (or femur) abuts the large bone of the lower leg (tibia) at the knee joint. During a total knee replacement, the end of the femur bone is removed and replaced with a metal shell. The end of the lower leg bone (tibia) is also removed and replaced with a channeled plastic piece with a metal stem. Depending on the condition of the kneecap portion of the knee joint, a plastic "button" may also be added under the kneecap surface.

The posterior cruciate ligament is a tissue that normally stabilizes each side of the knee joint so that the lower leg cannot slide backward in relation to the thigh bone. In total knee replacement surgery, this ligament is either retained, sacrificed, or substituted by a polyethylene post.

Knee replacement causes and symptoms:

Total knee replacement surgery is considered for patients whose knee joints have been damaged by either progressive arthritis, trauma, or other rare destructive diseases of the joint. The most common reason for knee replacement is severe osteoarthritis of the knees.

Regardless of the cause of the damage to the joint, the resulting progressively increasing pain and stiffness and decreasing daily function lead the patient to consider total knee replacement.

Knee replacement treatment:

Before surgery, joints adjacent to the diseased knee are carefully evaluated. Furthermore, all medications which the patient is taking are reviewed. Blood-thinning medications such as warfarin (Coumadin) and anti-inflammatory medications such as aspirin may have to be adjusted or discontinued prior to surgery. A total knee replacement generally requires between one and a half to three hours of operative time. After surgery, patients are taken to a recovery room, where vital organs are frequently monitored. When stabilized, patients are returned to their hospital room.

Routine blood tests of liver and kidney function and urine tests are evaluated for signs of anemia, infection, or abnormal metabolism. Chest X-ray and EKG are performed to exclude significant heart and lung disease which may preclude surgery or anesthesia. Finally, it is less likely to have good long-term outcome if the patient's weight is greater than 200 pounds. Excess body weight simply puts the replaced knee at an increased risk of loosening and/or dislocation.

Physical therapy (Physiotherapy) is an extremely important part of rehabilitation and requires full participation by the patient for optimal outcome. Patients can begin physical therapy 48 hours after surgery. Some degree of pain, discomfort, and stiffness can be expected during the early days of physical therapy. Knee immobilizers are used in order to stabilize the knee while undergoing physical therapy, walking, and sleeping. They may be removed under the guidance of the therapist for various portions of physical therapy.

It is important for patients to continue in an outpatient physical-therapy program along with home exercises for optimal outcome of total knee replacement surgery. Patients will be asked to continue exercising the muscles around the replaced joint to prevent scarring (contracture) and maintain muscle strength for the purposes of joint stability.