The knee is a joint which has three parts. The femur (thigh bone) meets the large tibia (shin bone) forming the patella (knee cap). This joint has an inner medial and outer lateral compartment. The kneecap (patella) joins the femur to form a third joint, called the patellofemoral joint. Cause of disease is degeneration of the cartilage of the knee and causes knee joint pain.
Knee joint pain can be caused by degeneration of the cartilage of the knee, sprains or strains, heavy physical activity, lack of use, tendinitis and meniscus tears. The pain can be constant or it can flare up now and then due to overuse.