Shoulder Bursitis

Causes

When the bursa becomes inflamed, it swells up and occupies more space. In doing so, the swollen bursa can further limit the size of the space (the subacromial space) in which the rotator cuff tendon moves. In certain extremes of motion, this can cause a painful impingement phenomenon. This mechanism can lead to further irritation and pain. Rotator cuff tendinopathy may often be the underlying mechanism causing shoulder bursitis. The rotator cuff muscles, which become tendons when attached to bones, are the dynamic structures that allow for the tremendous range of motions in multidirections that the shoulder is capable of producing. There are four muscles that make up the rotator cuff: supraspinatus, infraspinatus, teres minor, and subscapularis. The shoulder is referred to as a ball-and-socket joint—the rounded ball of the humerus fits into the shallow, saucer-like socket of the glenoid. A golf ball resting on a tee is an appropriate analogy. This great mobility of the shoulder joint does come at a price, with the shoulder joint having increased susceptibility to injury and overuse.

Figure 1 Inflammation of the Bursa Occurs Between the Rotator Cuff Tendons and the Shoulder Blade

Clinical Evaluation

Rotator cuff problems generally occur in older populations, ages 40 to 50, who may or may not be athletically inclined. It can present either insidiously, which may or may not involve an increase in certain shoulder movement activities, or in a more acute setting after a specific injury. Any change in the intensity, frequency, or duration of an activity, be it at work or at home, as well as any new activity could contribute to developing an overuse injury. Age-related changes to tendons result in their less pliable or elastic (rubber bandlike) quality; this can lead to fraying, swelling in the tendon, calcified deposits, and frank tears. Thus, as we get older, we may be more prone to overuse injuries such as rotator cuff tendinopathy and shoulder bursitis, and unfortunately, we may recover less well from them.

In the athletic population, rotator cuff tendinopathy can develop in any overhead throwing or motion sport such as baseball and softball, racquet sports such as badminton and tennis, swimming, and water polo.

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