ALPSA lesion (Anterior labroligamentous periosteal sleeve avulsion). Axial fat-saturated T1 weighted MR arthrographic image displays a chronically torn anteroinferior labrum, avulsed off together with a periosteal sleeve, which is bunched up medially as a fibrous scarred nodule (black arrows). Note the defect at the location of the normal attachment site of the labrum anteroinferiorly (blue arrow).