Tendons are tough, flexible, fibrous bands of tissue that connect muscles to bones. When tendons become inflamed, irritated or suffer microscopic tears, the condition is called tendonitis. Tendons can be small, like the delicate, tiny bands in the hands, or large, like the heavy, ropelike cords that anchor the calf or thigh muscles. In most cases, the cause of tendonitis is unknown; when a cause can be identified, the condition usually happens for one of two reasons:
Overuse – A particular body motion is repeated too often.
Overload – The level of a certain activity, such as weightlifting, is increased too quickly.
Rarely, tendonitis is caused by an infection, such as gonorrhea. Tendonitis is most common in the shoulder, elbow, knee, wrist and heel, although it can happen anywhere that tendons are found in the body. For uncertain reasons, tendonitis is also common in people with diabetes. In recent years, a rare cause of tendonitis (or other tendon disease, including rupture) has been recognized: the use of certain antibiotics, including ciprofloxacin or levofloxacin. Why this happens is unknown.
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