Evaluation of variations of the glenoid attachment of the inferior glenohumeral ligament by magnetic resonance arthrography

OBJECTIVE: To evaluate the anatomical variations of the attachment of the inferior glenohumeral ligament (IGHL) to the anterior glenoid rim. MATERIALS AND METHODS: This was a retrospective review of 93 magnetic resonance arthrography examinations of the shoulder. Two radiologists, who were blinded to the patient data and were working independently, read the examinations. Interobserver and intraobserver agreement were evaluated. The pattern of IGHL glenoid attachment and its position on the anterior glenoid rim were recorded. RESULTS: In 50 examinations (53.8%), the glenoid attachment was classified as type I (originating from the labrum), whereas it was classified as type II (originating from the glenoid neck) in 43 (46.2%). The IGHL emerged at the 4 o’clock position in 58 cases (62.4%), at the 3 o’clock position in 14 (15.0%), and at the 5 o’clock position in 21 (22.6%). The rates of interobserver and intraobserver agreement were excellent. CONCLUSION: Although type I IGHL glenoid attachment is more common, we found a high prevalence of the type II variation. The IGHL emerged between the 3 o’clock and 5 o’clock positions, most commonly at the 4 o’clock position.