Shoulder strains are very common conditions in which the area surrounding the shoulder tendons becomes irritated. Many cases develop suddenly after increasing activity; others develop slowly over time as a result of degenerative changes around the shoulder. Most patients describe a sharp pain in the upper/outer arm when lifting the arm overhead or trying to put on a jacket. Strength and motion are preserved, but painful. Initial treatment includes activity modification, anti-inflammatory medication and corticosteroid injection. Physical therapy is often helpful if the condition persists. In refractory cases, an MRI may show pathology that is amenable to surgical treatment.