Which test assesses inferior shoulder instability?

• A. Push-Pull test
• B. Sulcus sign
• C. Apprehension test
• D. Jerk test

Answer: (B)

Inferior instability of the shoulder is due to laxity of the inferior capsule and the inferior glenohumeral ligament, allowing downward translation of the humeral head. The sulcus sign directly tests for this by applying downward traction to the arm while the patient sits or stands. If a noticeable indentation or sulcus forms just below the acromion, it indicates inferior translation of the humeral head and capsule laxity. A sulcus of about 1 centimeter or greater is typically considered a positive sign, reflecting inferior instability. This test is especially useful when instability is multidirectional or when inferior laxity is suspected, whereas the other tests primarily provoke anterior or posterior instability or a clunk/slack sensation in different directions, not specifically inferior laxity.