Knee Replacement Information: Symptoms & Causes

What are some common causes of knee pain?

Painful knee problems can develop slowly over time from degenerative osteoarthritis or Rheumatoid arthritis. Symptoms of joint degeneration can include: a painful sensation of bones rubbing together or ‘catching;’ pain and/or instability while walking or standing; aching or swelling in the knee joint or surrounding tissues. Knee pain can also occur suddenly as a result of unnatural twisting or direct trauma to the knee joint, such as accidents, falls and sports injuries. Both trauma and degeneration can cause tiny portions of bone or cartilage to break off and float around in the knee joint. This becomes problematic when the loose debris interferes with movement and causes pain in or around the joint.

Dislocating the knee cap (patella), a small triangular-shaped bone covering the front of your knee, is another common cause of knee pain. This occurs when patella slips or is forced out of place, usually to the outside of the knee. Another cause, chronic hip or foot pain, may alter the gait in such a way that unduly stresses parts of the knee and refers pain to the joint.

What is osteoarthritis?

Osteoarthritis (OA) is a chronic disease that affects millions of people. It is caused by the breakdown of cartilage or natural cushion at the end of the bones. As cartilage deteriorates, bones begin to rub against one another, causing stiffness, pain and discomfort that limit movement and range of motion. OA occurs most often in the knees, hips and hands. Over time, it can damage ligaments, menisci and muscles, and may create the need for a knee replacement or arthroplasty.

What is Rheumatoid arthritis?

Rheumatoid arthritis (RA) is an autoimmune disease that causes the body's immune system to attack normal joint tissues, causing painful inflammation stiffness or swelling within the joint lining. The causes of RA are unknown. However, research has shown that genetic factors may predispose certain individuals to the disease, and that external or environmental factors, such as infection, can inexplicably trigger RA symptoms.

After the onset of RA, tendons become inflamed and may tear apart. Swelling can damage or destroy ligaments, joint cartilage and bone. Erosion, pain and deformity may become so severe that a joint replacement becomes necessary to restore the quality of life.

What is osteonecrosis?

Osteonecrosis, sometimes called avascular necrosis, aseptic necrosis or ischemic necrosis, refers to the temporary or permanent loss of blood supply to bone. The lack of blood causes affected portions of the bone to die and collapse. If the affected bone is near a joint, the joint surface can collapse, causing extreme pain and loss of function. Though it can occur in any bone, the ends of the femur, upper arm bone, knee bones, hip bones, shoulders and ankles are most often affected. The American Academy of Orthopedic Surgeons estimates that 10,000 to 20,000 people develop osteonecrosis each year.