The Science of Bursitis / Tendinitis

Shoulder bursitis, specifically subacromial bursitis, involves inflammation of the small fluid-filled sac (bursa) that sits between your rotator cuff tendons and the bony roof of your shoulder (acromion). This bursa normally allows smooth gliding of the rotator cuff tendons beneath the acromion during arm movement. When the subacromial space becomes narrowed due to bone spurs, poor posture, muscle imbalances, or repetitive overhead activities, the bursa becomes compressed and irritated. This compression leads to inflammation, thickening of the bursa walls, and production of excess synovial fluid, creating a cycle of swelling and further compression. The condition often coexists with rotator cuff tendinopathy and shoulder impingement syndrome, as they share similar mechanical causes. The inflamed bursa can contribute to pain and dysfunction, but it's usually a secondary problem rather than the primary issue. Understanding this relationship is crucial because treating only the bursitis without addressing underlying mechanical problems often leads to recurrence. Acute bursitis may result from direct trauma or sudden overuse, while chronic bursitis typically develops gradually from repetitive microtrauma and sustained mechanical irritation.