The bow test for the subacromial impingement syndrome

Because of the biomechanics of the glenohumeral joint, impairment of rotator cuff function leads to cranial migration of the humeral head, impinging the greater tubercle against the coraco-acromial arch and irritating the subacromial bursa. When bursal irritation has become established, active elevation of the arm against gravity will cause pain within an arc of motion. When a patient with a painful arc is asked to bend forward and let the arm hang, the same arc will become painless. This noninvasive clinical test called the "bow test" is a simple means by which subacromial impingement can be clinically identified as the source of pain in the painful arc of shoulder motion.