People from all ages and walks of life can be afflicted with shoulder problems.  Approximately 15-20 percent of all injuries evaluated in the orthopaedic or sports medicine clinic involve the shoulder or one of the bones or muscles that make up the joint.  Although some of these injuries may be traumatic and/or acute, the majority of them are of a chronic nature and typically result from overuse.

The rotator cuff is a group of four muscles that rotate the arm bone internally and externally.  They have in common a point of insertion on the humerus (arm bone) and function to pull on their bony attachment from various points around the shoulder.  The combination of similar and opposing forces generated by these muscles are responsible for the rotary movements of the shoulder.

The rotator cuff is a rather deep muscle group that is difficult to visualize from the surface on most people.   It is situated above and around the humeral head (aka the ball of the ball and socket) and below a portion of the shoulder blade known as the acromion in an area known as the subacromial space.  The total contents of the subacromial space includes the rotator cuff and/or rotator cuff tendon and the bursa which gives the muscles a mechanical advantage.

There is an arbitrary classification of acromions which indicate the thickness of the process.  People with a very thick acromion (Grade III) have less room in their subacromial space and visa versa.

When the arm is raised (as if to answer a question in class) the humerus will move into a position such that the area in the subacromial space diminishes.  In a normal shoulder, this should not impinge upon the contents of the space.  However in some people the humerus does impinge upon the rotator cuff tendon and/or the bursa. 

If someone is prone to shoulder impingement and they have a job or hobby that routinely requires them to perform overhead activities, the bursa and tendon can become painful and inflamed.  In more advanced cases, the rotator cuff tendon may actually tear.

When a patient complains of shoulder pain that appears to be associated with the subacromial space he or she needs a complete examination of the shoulder.  This includes examining for points of tenderness throughout the shoulder as well as assessing for impingement and for strength deficits in the muscle itself.

Most people require an X-ray as well to determine if their is any obvious bony pathology within the shoulder joint.  With the X-ray of the shoulder, the doctor should be able to assess the thickness of the acromion and to identify other bony problems within the shoulder.   Unfortunately, the radiograph will not demonstrate most muscular and tendionous problems.

Depending on the findings on X ray and physical exam, some people may require an additional imaging study to evaluate the subacromial space.  This could be an MRI or a special X-ray called an arthrogram. 

If there is no tear demonstrated either on physical examination or on an imaging study, conservative or minimally invasive therapy is usually sufficient.  This could include oral anti-inflammatory medications, physical therapy and joint injections.

If a tear is found in the rotator cuff muscle or tendon, a surgical procedure is often warranted.   Depending on the thickness of the tear and the needs of the patient, several different procedures are available.

For tears that do not involve the full thickness of the rotator cuff, an arthroscopic procedure is often sufficient.  The surgeon will introduce his camera and tools into the shoulder through small portals in the skin.  The subacromial space is cleaned out and the acromion is contoured to avoid future impingement.

For tears that do involve the full thickness of the muscle, an open procedure is often required.  Depending on the situation, the open procedure may either involve an arthroscopically assisted surgery that includes the surgeon splitting the deltoid muscle or a full open procedure that requires the deltoid to be completely pulled down to expose the rotator cuff insertion.

Regardless of the specific surgical procedure a period of rehabilitation will be necessary to ensure maximal benefit. 

If you have a job or hobby that involves repetitive motion of your shoulder, especially overhead motion, and you have a painful or sore joint, you should see an orthopaedic doctor at your earliest convenience.  And, of course, if you have any painful joint, evaluation is generally warranted.