Also called posterosuperior impingement
Impingement of posterior supraspinatus or anterior infraspinatus or both between humeral head and posterior glenoid during extreme abduction and external rotation (overhead movement)
Secondary to abnormality in the supraspinatus, infraspinatus, posterosuperior labrum or humeral head or combination of above
Arthroscopic criteria:
Posterosuperior labral fraying or tear
Articular irregularity of supraspinatus or infraspinatus or both
Contact of cuff tendons on posterosuperior glenoid in abduction and external rotation
MRI:
Irregularity of undersurface of rotator cuff - abnormal signal, tears or both
Capsular laxity with anterior translation of humeral head
Fraying or tear or both of posterosuperior labrum
Cyst like change posterolateral humeral head at attachment of infraspinatus tendon and posterior fibers of supraspinatus (may be secondary to impaction or traction).
References:
1. Giaroli EL et al. MRI of Internal Impingement of the Shoulder. AJR 2005; 185:925-929
