Tendinitis is inflammation of a tendon. A tendon is a cord or band that connects a muscle to a bone.
Tendons are usually smooth and strong. With age or overuse, tendons can become worn and weak, leading to tendinitis. Tendinitis occurs most often in the shoulder, elbow, wrist, hip, knee, and ankle.
Tendinitis is caused by overuse, injury, or aging. It can be associated with inflammatory diseases that occur throughout the body, such as rheumatoid arthritis. Rarely it is caused by an infection such as gonorrhea.