Rotator cuff tendonitis can be a very painful and frustrating injury that you do not want to happen. Thus, you should be knowledgeable about what causes this condition so that you will be able to prevent it. The most common is the overuse and overbearing of muscles in the shoulder area. Too much usage puts a lot of stain on the muscles, eventually leading to muscle tear. Other factors such as age, smoking, and diabetes mellitus can also increase chances of a tear. Take note that once a tear in the rotator cuff occurs, the condition is more likely to recur.