Joint replacement

TKRWhat is a knee replacement?

A Knee Replacement is an operation that replaces a knee joint that has been damaged by arthritis or trauma. Your knee joint is a hinge joint between your thigh bone (femur) and your shin bone (tibia). The knee-cap (patella) moves along the lower surface of the femur. The joint is surrounded by cartilage, muscles and ligaments which enable the joint to move smoothly in its correct alignment.

Articular cartilage coats the joint surfaces allowing free flowing movement of the knee joint. Arthritis occurs when the cartilage lining the joint is worn away leaving the underlying bone exposed. The joint then becomes rough and distorted, resulting in pain and restricted movement. A limp often develops. As the joint begins to move incorrectly the thigh muscles become weak and wasted. Physical activity often decreases resulting in further muscle wasting. Pain often causes the soft tissues behind the knee to become tight and develop a flexion contracture where the knee is unable to straighten completely.

The Knee Replacement operation replaces the worn lower surface of the femur and the upper surface of the tibia to remove the varus or valgus deformity. The damaged surfaces are removed and then replaced by both a femoral and a tibial component of the prosthesis.

A plastic spacer lies between the two components.  If the back of the patella is worn, it may also be  
re-shaped and re-surfaced with a plastic button. This new joint is designed to ultimately relieve pain, correct deformity, decrease stiffness and improve mobility.

Download our Patient Guide on Knee Replacement (PDF 4MB)

THRWhat is a hip replacement?

A Hip Replacement is an operation that replaces a hip joint that has been damaged by arthritis or trauma. Your hip joint is a simple  ball and socket joint at which your thigh bone (femur) joins your pelvis at your acetabulum. The joint is surrounded by cartilage, muscles  and ligaments, which allow the joint to move smoothly in all directions.

Articular cartilage coats the joint surfaces allowing free flowing movement of the hip joint. Arthritis occurs when the cartilage lining the joint is worn away leaving the underlying bone exposed. The joint then becomes rough and distorted, resulting in pain and restricted move-ment. A limp often develops. As the joint begins to move incorrectly the thigh muscles become weak, wasted and tight. Physical activity often decreases resulting in further muscle wasting. There is a tendency for your leg to start turning out so that your toes point further out to the side. The muscles at the front of your hip joint begin to tighten causing you to develop a  leaning forward posture.

The Hip Replacement is a prosthesis,  which has the same basic parts as your own hip. The worn head of the femur is removed and a ball replaces it. There is a stem attached which is inserted into the femur for stability. A cup replaces the worn acetabulum. The ball and cup slide smoothly on each surface, as with a healthy hip, allowing you to move freely and without pain. Your doctor must dislocate your hip in order to do the work on your hip joint, therefore for a limited time after your surgery, special care will need to be taken in order to move within a safe range of movement.

Download our Patient Guide on Hip Replacement (PDF 3.5MB)