Anterior labroligamentous periosteal sleeve avulsion lesion at the superior glenoid labrum.

An unusual type of anterior labroligamentous periosteal sleeve avulsion (ALPSA) lesion in the superior, instead of the usual inferior, part of the anterior glenoid labrum is presented in a 33-year-old man who sustained a traumatic dislocation of his left shoulder. Magnetic resonance imaging raised the possibility of an ALPSA lesion and later arthroscopy confirmed the diagnosis. Arthroscopic repair of the lesion was performed after the labral avulsion was lateralized.