Tendons are bundles of white fibrous connective tissue that attach a muscle to a bone. They are similar to ligaments that attach bone to bone. Tendonitis is the result of a tendon becoming painfully inflamed and swollen following injury or the repeated stress of an activity. The tendons most commonly affected are those associated with the joint capsules of the shoulder, elbow, and hip, as well as those that move the wrist, hand, thigh, and foot. Rest, ice, and anti-inflammatory medication will often relieve the inflammation.