Over half of adults will experience troublesome shoulder pain. Most commonly it is associated with a low-grade injury such as putting a suitcase in an overhead compartment, retrieving something from the backseat, or an awkward stretch into a closet. Initially, the pain may be just a tweak and gone by morning but within a few days can become severe and disrupt of daily living, especially sleep.
Because just about everybody’s heard of the rotator cuff, the understandable assumption is that the rotator cuff has been torn and surgery may be necessary.
Happily, the reality is quite different. The pain comes from the rotator cuff but rarely is it torn.
The rotator cuff is a complex of muscles and tendons that pivots or rotates the head of the humerus (arm bone) under the roof of the shoulder outlet (acromion).
In healthy middle-aged adult, there is often not much more than a millimeter or so of clearance for the rotator cuff to rotate beneath the underside of the acromion. Often even the most minor event can cause a bit of inflammation in the rotator cuff with resultant swelling. The swelling increases the thickness of the rotator cuff causing it to rub to impinge against underside of the acromion. Hence the name, impingement tendinitis.
The more it rubs, the more inflamed and swollen it becomes so the condition may seem to be self-perpetuating.
The key is to eliminate the impingement by reducing the swelling in the rotator cuff.
Often a few weeks of rest with some NSAIDS (e.g. Advil/Aleve) is all that’s necessary. Physical therapy can be helpful in restoring tone to the muscles which evens out the age degraded arc of rotation to that of to that of a younger shoulder.
About 90% of patients will get better with one or two injections of a blend of local anesthetic and a steroid (cortisone) layered over the rotator cuff. The anesthetic immediately relieves the pain for a few hours, thus confirming the diagnosis. Within a few days the steroid anti-inflammatory reduces the swelling of the tendon and restores clearance.
Both of the following articles are a good general discussions of shoulder pain, for which there can be several causes, but remember, 90% of the time it’s a plain old impingement tendinitis.