A tendon is a cord which connects muscle to bone or other tissue. Similar to the wearing process on the sole of a shoe which eventually splits from overuse, most tendonitis is a result of the wearing process that takes place over a period of years. Typically, tendonitis is one of several types:
Acute tendonitis following some overuse problem such as excessive ball throwing and other sports- or work-related activities.
Chronic tendonitis which can be attributed to degenerative disease or repetitive wear and tear due to age.
The splitting and tearing of tendons which may result from acute injury or degenerative changes in the tendons due to advancing age. Rotator cuff injuries are among the most common of these disorders. The rotator cuff is composed of muscles and their tendons which provides shoulder motion and stability.