Type of shoulder instability	History	Findings on physical examination
Anterior instability	Usually occurs in men in their early 20s Direction of force anterior on arm or posterior on shoulder “Dead arm” syndrome common Often associated with acute injury but can be from overuse, such as in baseball pitchers	Patient presents acutely with arm in abduction and internal rotation, perhaps with palpable anterior mass Axillary nerve injuries can occur Drawer and load-and-shift tests result in anterior displacement and popping Apprehension and relocation tests positive
Posterior instability	More commonly associated with seizure or severe electric shock Offensive linemen vulnerable to repetitive subluxation Subluxation occurs when arm is in a foward-flexed, adducted and internally rotated position Posterior shoulder pain with activity	Patient presents with arm externally rotated and a prominent humeral head on the posterior shoulder Missed clinically in 50% of cases Posterior joint line tenderness on palpation Posterior rotator cuff weakness Drawer and load-and-shift tests result in posterior displacement and popping Apprehension and relocation tests negative
Multidirectional instability	Most commonly occurs in athletes with congenital hyperlaxity of multiple joints in sports requiring overhead arm motions Usually vague symptoms with activity	Evidence of generalized ligamentous laxity Usually rotator cuff weakness is present Drawer and load-and-shift tests result in anterior and posterior planes of displacement without popping Positive sulcus test is pathognomonic