What is the purpose of the O'Brien Test?

The O'Brien Test is specifically designed to help identify a superior labrum anterior to posterior (SLAP) lesion, which is a type of shoulder injury involving the labrum, a fibrocartilaginous structure that provides stability to the shoulder joint. During the test, the patient is asked to hold their arm at 90 degrees of forward elevation with the elbow straight, and the examiner applies downward pressure while the arm is initially positioned in thumb-down (internal rotation) and then again in thumb-up (external rotation). A positive test elicits pain or a feeling of instability in the shoulder, particularly in the thumb-down position, indicating a potential SLAP lesion due to the intrusiveness of this injury on shoulder biomechanics.

The focus on SLAP lesions distinguishes the O'Brien Test from other evaluations, such as those aimed at assessing acromioclavicular joint pathology, thoracic outlet syndrome, or the integrity of the elbow medial collateral ligament (MCL). Each of these other conditions would typically require different testing mechanisms reflecting their unique anatomical and functional considerations.