Shoulder impingement syndrome accounts for up to 65% of all shoulder complaints. It results from repetitive pinching of the soft tissues between the acromion of the scapula and greater tuberosity of the humerus with arm elevation. This pinching most often occurs at the tendinous portion of the supraspinatus, a rotator cuff muscle, and can make reaching overhead difficult, cause pain when sleeping on the affected side, and limit range of motion.
The rotator cuff muscles help to stabilize and center the humerus in the glenohumeral joint as the arm raises and goes through different ranges of motion. If these muscles aren’t working in sync to stabilize, the space in the glenohumeral joint becomes reduced and pinching occurs.
Other mechanical and structural factors can also be involved and lead to impingement syndrome. The way the stabilizing muscles of the scapula are functioning must be addressed and things such as the anatomy of the acromion, arthritic changes, or bone spurs may be contributing factors.
The development of shoulder impingement syndrome is commonly seen with rounded, slouched postures, jobs requiring a lot of overhead work or lifting, and overhead athletes in sports such as swimming, baseball, or tennis.
Impingement syndrome responds very well with conservative care because it is mechanical in nature. Early treatment can help prevent the tendon from fraying and eventually progressing into a rotator cuff tear.