FROM PAINFUL DISABILITY TO PAINLESS MOBILITY
With age and also with rheumatoid arthritis and sometimes due to old malunited fractures the weight bearing surfaces of the knee joint become worn away. They are no longer smooth and free running and this leads to stiffness, disability and pain. Eventually the joint wears away to such an extent that the bone of the femur grinds on the bone of the tibia. A total knee replacement replaces these surfaces with plastic and metal. The femoral replacement is a smooth metal component, which fits snugly over the end of the bone. The tibial replacement is in two parts, a metal base sitting on the bone and a plastic insert, which sits between the metal base on the tibial and femoral component. If necessary the patellar surface (under the knee cap) is replaced with a plastic button, which glides over the metal surface of the femoral replacement.
WHAT IS INVOLVED IN TOTAL KNEE REPLACEMENT
To be able to replace the surface of the knee joint a 20cm incision is made down the front of the knee and the joint opened. The bony overgrowth, which commonly occurs in arthritis of the knee, is trimmed away and the joint surfaces removed. This involves some shaping of the bone so that the joint replacement components sit firmly on the bone. In the replacements now being used the bone then grows into the roughened surfaces of the replacement, anchoring it down. In addition, bone cement is used to hold the components in place.
The recovery from the operation requires about 5-7 days in hospital. The day after surgery you will commence your rehabilitation with physiotherapy. This involves exercises to improve the strength of the muscles and regain the range of motion of the knee. On the first day after surgery your physiotherapist will begin to assist you to get out of bed and walk a small distance. This will be progressed over the next 7 days, till you are independently mobile. The exercising and mobilising of the knee will cause some discomfort and swelling, however this is normal, and is just part of the healing process. If pain is preventing you from exercising effectively, you should discuss this with your nurse. An ice pack will be given after the bandages are removed and should be used regularly to help reduce the pain and swelling in your knee. The swelling normally takes many weeks to months to subside which cause a tight feeling in the knee.
After your hospital stay:
We will organise your rehabilitation to continue after you are discharged from hospital, either staying in a rehabilitation unit or going home. You will generally be able to leave with the aid of a single walking stick or crutches. While at home you should continue your straight leg raising and range of movement exercises, as well as walking regularly. If at any stage you develop a fever or the wound becomes red or painful you should bring this to the attention of our staff immediately. It is usual to be reviewed by the doctor at 6-8 weeks after surgery, with new x-rays.
After you have had this surgery you MUST take antibiotics prior to any other operations in the future, including dental work. This is to prevent germs lodging on the implant and causing infection in the joint.
Potential Complications Related To Surgery:
■ Stiffness: After a total knee replacement the knee is usually quite stiff for up to 3 months. Early and aggressive postoperative physiotherapy and exercises will reduce the risk of stiffness and promote a full range of motion following total knee replacement. The average range of motion following a total knee replacement can be expected to be 115°.
■ Deep vein thrombosis and pulmonary embolus: A combination of immobilisation of the limb, smoking and the oral contraceptive pill or hormonal replacement therapy all multiply to increase the risk of a blood clot. Any past history of blood clots should be informed prior to your operation. Prevention of deep vein thrombosis involves a rapid recovery program, with patients getting out of bed within 24hours following the surgery, and the administration of anticoagulants in the form of Aspirin or Warfarin.
■ Surgery is carried out under strict germ free conditions in a modular operation theater with HEPA filters and positive pressure system. Antibiotics are administered intravenously at the time of your surgery. Despite these measures, following surgery there is a less than 1 % chance of developing an infection. Most commonly these are superficial wound infections that resolve with a course of antibiotics. More serious infections may require further hospitalization and surgical and prolonged antibiotic therapy.