You are probably reading this booklet because your surgeon has recommended total joint replacement to treat your knee problem. This booklet will answer general questions about your surgery and hopefully put some of your fears to rest. Share this booklet with your family. It explains what will happen before, during, and after knee replacement surgery. But, it cannot answer all of the questions you might have about your own knee problem and the treatment of it. Your surgeon can answer any questions you and your family still have after reading this booklet. This booklet is not meant to replace the advice of your doctor, surgeon, therapist, or nurse.
The Knee Joint
A joint is formed where two or more bones meet. The knee joint is a hinge-type joint and is formed where the thighbone (femur) meets the shinbone (tibia). The thighbone is rounded on the end and rocks back and forth on the flat surface formed on the end of the shinbone. A smooth cushion of articular cartilage covers the surface ends of both of these weight bearing bones. The articular cartilage is kept slippery by fluid made by the synovial membrane (joint lining). Since the cartilage is smooth and slippery, the bones move against each other easily and without pain. Large ligaments, tendons, and muscles around the knee joint hold the bones in place.
The kneecap (patella) is also a part of the knee joint. It is located on the front of the knee and keeps the tendon that comes across the front of the knee from rubbing against the joint.
Causes for Joint Replacement
Arthritis is the wearing away of the surfaces (articular cartilage) of a joint. This wearing away can be caused by aging, injury, or disease. As the joint surfaces slowly wear away, the raw bones begin to rub together whenever the joint moves. This rubbing causes pain and further roughening of the surfaces. The “dull, aching pain” is usually worse when the joint moves.
If the blood supply for the thighbone is decreased, part of the bone will die and break under weight bearing. The result is a very painful joint.
Sports or work-related injuries to the ligaments or other cartilage in the knee can cause abnormal wearing of the articular cartilage on the ends of the bones where the bones meet.
Once the articular cartilage wears out, a knee replacement is often needed. You would be considered for total knee replacement if:
- You have pain every day and a lot of pain at night.
- Your pain limits your work, play, or activities of daily living.
- Your knee “gives way” often.