Total Joint Replacement
What is total joint replacement?
An arthritic or damaged joint is removed and replaced with an artificial joint called prosthesis.
What is a joint?
A joint is formed by the ends of two or more bones which are connected by thick tissues. For example, your knee joint is formed by the lower leg bone, called the tibia or shin bone, and your thighbone, called the femur. Your hip is a ball and socket joint, formed by the upper end of the femur, the ball, and a part of the pelvis called the acetabulum, the socket.
The bone ends of a joint are covered with a smooth layer called cartilage. Normal cartilage allows nearly frictionless and pain-free movement. However, when the cartilage is damaged or diseased by arthritis, joints become stiff and painful. Every joint is enclosed by a fibrous tissue envelope or a capsule with a smooth tissue lining called the synovium. The synovium produces fluid that reduces friction and wear in a joint.
Why is total joint replacement necessary?
The goal is to relieve the pain in the joint caused by the damage done to the cartilage. The pain may be so severe, a person will avoid using the joint, weakening the muscles around the joint and making it even more difficult to move the joint. A physicial examination, possibly some laboratory tests and x-rays will show the extent of damage to the joint. Total joint replacement will be considered if other treatment options will not relieve your pain and disability.
How is a total joint replacement performed?
You will be given an anesthetic and the surgeon will replace the damaged parts of the joint. For example, in an arthritic knee the damaged ends of the bones and cartilage are replaced with metal and plastic surfaces that are shaped to restore knee movement and function. In an arthritic hip, the damaged ball (the upper end of the femur) is replaced by a metal ball attached to a metal stem fitted into the femur, and a plastic socket is implanted into the pelvis, replacing the damaged socket.
The materials used in a total joint replacement are designed to enable the joint to move just like your normal joint. The prosthesis is generally composed of two parts: a metal piece that fits closely into a matching sturdy plastic piece. Several metals are used, including stainless steel, alloys of cobalt and chrome, and titanium. The plastic materials are durable and wear resistant (polyethylene). A plastic bone cement may be used to anchor the prosthesis into the bone. Joint replacements also can be implanted without cement when the prosthesis and the bone are designed to fit and lock together directly.