Abstract
Distinguishing between partial-thickness and small focal full-thickness tears of rotator cuff may be important for determining the appropriate surgical treatment options and repair constructs in the care of patients with rotator cuff pathology. This article presents a simple intraoperative technical trick to aid in identification of small full-thickness tears of the superior rotator cuff. The relatively higher-pressured subacromial space and the low-pressured glenohumeral joint are separated by the supraspinatus tendon. When this barrier is compromised due to a full-thickness tear, free fluid flows from high to low pressure down the native pressure gradient. This is seen as the movement of air bubbles into the glenohumeral joint from the subacromial space and can be used to identify the presence of a full-thickness rotator cuff tear on diagnostic arthroscopy.