Cause of Symptoms: Rotator Cuff / AC-Joint Injuries are most often caused by overuse or blunt trauma directly to the shoulder or to the upper extremity in activities such as falling down and attempting to catch ones self with an outstretched hand.
Direct trauma can cause micro tears, resulting in inflammation and swelling of the associated tissues. Swelling causes pressure on surrounding tissues resulting in compression of the nerves and resulting pain. This pain in turn causes limited activity, allowing the injured muscles to atrophy due to the trauma, and ultimately resulting in a muscle imbalance when left unrehabilitated for any length of time.
Rotator Cuff Injuries caused by overuse result in one muscle group becoming stronger than the other resulting in impingement of associated tissues due to the joint being imbalanced because the stronger muscle group(s) is pulling too hard in one direction in comparison to its antagonist or opposing muscle group.
In either case, although the reasons for injury are different, the result is the same and can be corrected in the same manner, by eliminating the muscle and joint imbalance that exists. (Only if rotator cuff muscles and bursa are not torn)