A patient with shoulder pain following a motor vehicle collision exhibits a painful arc during arm elevation. This finding is indicative of which condition?

• A. Rotator cuff tear
• B. Acromio-clavicular joint dysfunction
• C. Glenohumeral instability
• D. Shoulder impingement syndrome

Answer: (B)

The painful arc during arm elevation is a significant clinical finding often associated with shoulder conditions. In this context, the correct condition that this indicates is shoulder impingement syndrome.

Shoulder impingement syndrome occurs when the tendons of the rotator cuff become irritated and inflamed as they pass through the shoulder joint, particularly across the acromion. As the arm is raised, especially between 60 and 120 degrees of abduction, patients experience pain due to the compression of these tendons against the bony structures of the shoulder. This painful arc is a hallmark sign of this condition and guides clinicians in diagnosing impingement as opposed to other shoulder pathologies.

While the other conditions can also be associated with shoulder pain, they do not characteristically present with the same pattern of a painful arc during arm elevation that is specific to shoulder impingement syndrome. For instance, a rotator cuff tear may present with weakness in addition to pain but not always exhibit a clear painful arc. Acromio-clavicular joint dysfunction often results in localized pain at the AC joint rather than a painful arc, and glenohumeral instability typically presents with a sense of apprehension or dislocation but not specifically a painful arc. Thus, understanding