Inter-rater and intrarater reliability of superior labrum anterior to posterior lesion classification using magnetic resonance arthrography

The glenoid labrum is a fibrocartilaginous ring that affixes the joint capsule and ligaments of the glenohumeral joint. Superior labrum anterior to posterior (SLAP) lesions are a subset of injuries that affect the superior glenoid labrum, most common in laborers and overhead-throwing athletes. In 1990, Snyder et al classified SLAP lesions into one of four types. Later, Maffet et al expanded this scale to include three additional subclassifications. At present, arthroscopy is considered the gold standard for SLAP tear diagnosis. Classification under arthroscopy has demonstrated low to moderate inter-rater reliability. Magnetic resonance arthrography (MRa) is an alternate, less invasive test for diagnosing SLAP lesions. The reliability of MRa for diagnosing slap tears is uncertain.