How is the AC compression test performed?

How is the AC compression test performed?

• A. Examiner applies medial compression across the shoulder girdle by squeezing clavicle and scapula together.
• B. Examiner thumbs clavicle laterally while scapula is stabilized.
• C. Arm is abducted to 90 degrees with horizontal adduction.
• D. Patient performs a shoulder shrug to test AC stability.

Answer: (A)

AC joint stability is tested by applying medial compression across the shoulder girdle. The examiner places hands on the clavicle and the scapula (or just the distal clavicle and acromion/spine of the scapula) and gently squeezes them toward each other, loading the acromioclavicular joint. If this produces sharp pain at the AC joint or reveals a visible step-off, the test is considered positive for AC joint injury or separation. This maneuver specifically stresses the AC ligaments and their stability, which is why it’s the preferred method for assessing AC pathology. Other maneuvers stress the AC joint in different ways or involve other structures, so they’re not the classic AC compression test. For example, crossing the arm across the chest (horizontal adduction) also loads the AC joint but via a different mechanism, and a shoulder shrug primarily tests overall girdle stability rather than isolating the AC joint.

AC joint stability is tested by applying medial compression across the shoulder girdle. The examiner places hands on the clavicle and the scapula (or just the distal clavicle and acromion/spine of the scapula) and gently squeezes them toward each other, loading the acromioclavicular joint. If this produces sharp pain at the AC joint or reveals a visible step-off, the test is considered positive for AC joint injury or separation. This maneuver specifically stresses the AC ligaments and their stability, which is why it’s the preferred method for assessing AC pathology.

Other maneuvers stress the AC joint in different ways or involve other structures, so they’re not the classic AC compression test. For example, crossing the arm across the chest (horizontal adduction) also loads the AC joint but via a different mechanism, and a shoulder shrug primarily tests overall girdle stability rather than isolating the AC joint.