BACKGROUND & OBJECTIVE
Idiopathic frozen shoulder is a common cause of pain, restricted range of motion, and reduced function in the shoulder. It usually comes on unexpectedly and progresses slowly. It is thought to be self-limiting, often resolves spontaneously, and continues for an average of 30 months.
Although the cause for the symptoms of frozen shoulder is unknown, it is commonly thought to involve chronic inflammation, fibrosis and contracture of capsuloligamentous structures around the glenohumeral joint. This study questioned that explanation, asking whether reduced range of motion might be due to active muscle guarding. To answer this question, it measured passive range of motion under general anesthesia.
Five patients diagnosed with frozen shoulder volunteered for this study. Each had painful, global restriction of passive shoulder movement. Researchers measured passive shoulder range of motion into abduction and external rotation before and after general anesthesia.
Prior to anesthesia, passive range of motion into abduction was severely restricted in each patient. Four out of five were restricted in external rotation, and one had normal external rotation range of motion. After anesthesia, passive abduction ROM increased in