Scapulohumeral Dysfunction

The joint where the shoulder meets the shoulder blade—or scapula—features a pattern of motion called scapulohumeral rhythm. This pattern allows for smooth, pain-free, powerful shoulder movement. When the shoulder is engaged in overhead motion, approximately one-third of the movement occurs at the scapulothoracic joint, which two-thirds occurring at the glenohumeral joint. Muscle coordination and timing during these movements is extremely important. If this pattern of motion becomes irregular, it can result in shoulder pain. Other signs that something is awry with scapulohumeral rhythm include instability and clicking. In some cases, scapulohumeral dysfunction may lead to rotator cuff impingement. Abnormal scapulohumeral rhythm can be identified with strength and control tests, but imaging tests such as X-rays, MRIs, ultrasounds, and CT scans are ineffective in diagnosing this problem. Physical therapy—particularly scapular stabilization exercises—is very effective in correcting abnormal scapulohumeral rhythm. Therapists also may recommend the use of external stabilization devices, such as support tape or braces. Such structures aid in the restoration of normal positioning and help coordinate muscle firing patterns. Another key component of shoulder pain rehabilitation is the correction of neck or spine dysfunctions, which can refer pain to and impact nerve function in the shoulder. Attention to neck and spine issues is especially crucial in cases of chronic shoulder pain.