Anatomical variations of the anterosuperior labrum: Prevalence and association with type II superior labrum anterior-posterior (SLAP) lesions

Background: Anterosuperior labrum variations have been generally described as innocent anatomical variations without clinical significance. This study was intended to determine their prevalence and reveal their possible relationship with type II SLAP lesions. Materials and methods: A total of 713 consecutive shoulder arthroscopies were evaluated retrospectively for anterosuperior labrum variations and co-existing labral pathologies. Twenty two of these were excluded from the study due to the interobserver variability in the categorization process. The relationship of both these anatomic variants and shoulders with a normal appearing anterosuperior labrum to intra-articular pathology was analyzed statistically and compared with each other. Results: Found in 98 patients (14.18%), the anatomic variations in the anterosuperior labrum were classified into 3 groups as the sublabral recess (2.46%), the sublabral foramen (7.67%), and absent anterosuperior labrum with a cord-like middle glenohumeral ligament (4.05%). The latter 2 of these groups displayed a statistically significant relationship with type II SLAP lesions (21 of 53 and 23 of 28 patients; P = .0028 and P < .0001, respectively). Discussion: Although mostly considered as simple morphological variations, the anatomic variants of the anterosuperior labrum may predispose the shoulder to labrum pathologies by altering the intra-articular biomechanics. Conclusion: As previously suggested in the literature, certain anatomic variants of the anterosuperior labrum are associated with the development of SLAP lesions.