A B C D E F G H I J K L M N O P R S T U V W

KNEE REPLACEMENT

Why is a Knee Replacement performed ?

Knee replacement is performed when, as a result of arthritis, the smooth lining of the knee joint (cartilage) becomes worn away and the roughened bony surfaces beneath rub against one another. This causes pain in the knee joint, especially on movement, with stiffness. The knee may become quite deformed, and this may lead to knock-knees or bow legs, if both legs are involved. Other conditions such as rheumatoid arthritis, infections or fractures of the knee joint may also lead to cartilage damage and require replacement. Doctors will not suggest a knee replacement until all other treatment has been tried. This may consist of painkillers or anti-inflammatory drugs, physiotherapy, the use of walking aids, or other operations to realign the joint (tibial osteotomy).

Preparations needed for a Knee Replacement

You should expect to stay in hospital for 5 to 14 days, depending on your recovery and home support. Allow 6 to 12 weeks off for recovery. Whilst waiting for surgery, you should keep the knee as mobile as possible and avoid excess weight gain. If any other medical conditions develop, particularly any infection or ulceration on the leg, the surgeon should be notified. Bring a list of the drugs you take with you to hospital and tell the doctor of any allergies you have to drugs or metal.

What Happens during a Knee Replacement

The most commonly used type of replacement is a surface replacement in which the worn ends of the bone are covered with metal or plastic and the patient's own ligaments are retained to keep the joint stable. Rarely, a hinged knee joint which has a rigid hinge and requires no support from the patient's own ligaments is used. The operation is carried out under a general anaesthetic, although in some patients a spinal anaesthetic may be performed which anaesthetizes the lower body by injecting anaesthetic into the spine. With this anaesthetic a sedative is usually given. A cut is made on the front of the knee; the worn ends of bone are removed and replaced either with the new surfaces made of metal on the thigh bone (femur) and metal or plastic on the top of the shin bone (tibia), or a metal hinge. Both types are usually fixed in place using a special cement. The wound is closed with stitches or staples. You will wake up in a recovery ward where special equipment is kept to ensure your safety before returning to the ward.

Possible Complications during a a Knee Replacement

Knee replacement is a major operation and complications may occur. There is the risk of the anaesthetic and immediately after the operation there may be problems with bleeding or deep bruising. There is also a risk of a blood clot forming in the legs (deep venous thrombosis) which may require treatment with medicines to thin the blood. Rarely, one of these clots may travel to the lungs (pulmonary embolism) which may be serious. This may require drug treatment, or in very rare cases, further surgery. Some surgeons will recommend blood-thinning treatment as a preventive measure. In some patients after knee surgery some difficulty is experienced in regaining movement and intensive physiotherapy may be required. Occasionally a manipulation of the joint under anaesthetic may be required. Rarely, the wound becomes infected and antibiotics are needed, and even occasionally further surgery. It is unlikely that the knee joint will wear out. However, the artificial joint may become loose in the bone. Should this happen it may be possible to replace the joint again, or it may be necessary to remove the loose joint and stiffen the knee.

After a Knee Replacement

After surgery, painkillers are given by injection or mouth. There will be a drip in the arm to replace fluid and blood lost. Drainage tubes coming from the knee will be removed after 1 or 2 days. Surgeons differ in their treatment of knee replacements after operation. Some like to move the knee almost immediately on a special machine. Others prefer to keep the knee still for several days in bandages or plaster before moving it. After a few days you will be allowed up, occasionally with a supporting brace, until the muscles become strong again. You will need a walking frame or crutches until you can use sticks. When you leave hospital, you should be able to lift your leg straight off the bed and to bend the knee almost to a right angle. Knee replacement does not restore a full range of movement. The most that can usually be obtained is about 110 degrees. Increase in movement will be encouraged by physiotherapy and exercise. When you leave hospital you will be seen by the specialist after a few weeks for a routine check. You will have further checks to ensure that the joint is progressing satisfactorily. Patients with desk jobs may return to work after 6 weeks, but other patients with more active jobs may have to wait for up to 3 months. It may not be possible to return to jobs that involve heavy physical activity. Gentle exercise is allowed, but jogging and repetitious exercises involving impact to the foot are not. Gentle dancing and gardening is possible, although kneeling is not advised after joint replacement. Normal sexual activity may be resumed as comfort allows. Every effort should be made to avoid excessive weight gain.

If a Knee Replacement is not performed

If the knee is not replaced, the pain, stiffness and deformity will increase until the patient either requires a walking frame or, in the most severe cases, a wheelchair. Pain relief is difficult and regular drugs may be needed.