The healthy knee operates as a hinge joint. Three bones come together to form the knee: the thighbone (femur), shinbone (tibia) and kneecap (patella). The end of the femur, top of the tibia and back of the patella are covered in cartilage, a tough lubricating tissue that protects the bones during movement and keeps them from rubbing against each other. Synovial membranes produce synovial fluid which keeps the cartilage lubricated and healthy.
As we age, the cartilage in the knee can wear down. This makes us more susceptible to osteoarthritis, a degenerative disease that wears and tears at the healthy cartilage covering the knee joint. Osteoarthritis of the knee is one of the five most common causes of disabilities among older Americans, roughly as prevalent as cardiovascular disease. Others at risk for the disease include the obese, athletes who participate in high-impact sports and people who have sustained injury in the knee area. Some studies suggest genetic mutations may make an individual more likely to develop osteoarthritis over time. Once cartilage is destroyed, it cannot be replaced.
Symptoms of osteoarthritis include discomfort, swelling and stiffness in the knee and upper and lower leg and decreased range of movement. Symptoms will worsen if not addressed early on. In some cases, the cartilage may wear away completely. When this happens, the bones rub directly against each other making it extremely painful to move. As a result, you may choose to limit your physical activity to avoid pain which will weaken the leg muscles. It is important to make an appointment to see your doctor as soon as possible if you develop any symptoms of osteoarthritis.