The Science of Shoulder Impingement Syndrome

Shoulder impingement (subacromial pain syndrome) involves irritation of the rotator cuff tendons and bursa in the subacromial space. Despite the name, it's now understood as more than just mechanical compression. The tendons develop degenerative changes and the bursa becomes thickened, not from simple pinching but from a complex interaction of factors. Modern understanding shifts away from blaming the shape of your acromion (the 'hooked' acromion seen on X-rays is common in pain-free shoulders too). Instead, we focus on functional problems: how your shoulder blade moves, rotator cuff strength, and posture all play crucial roles. Shoulder impingement frequently coexists with rotator cuff injuries, as both conditions share similar underlying biomechanical issues. In some cases, untreated impingement may contribute to the development of shoulder bursitis, and chronic impingement can lead to compensatory patterns that contribute to frozen shoulder.