Lesions of the Shoulder- HAGL
The inferior glenohumeral ligament avulses from the inferior humeral neck. When this occurs, it looks like the capsule and the ligament is avulsed from the inferior humeral neck and ripped off. This injury occurs due to shoulder dislocation. HAGL lesions usually occur due to combined hyper abduction and external rotation. In general, anterior dislocations (which are over 90% of the dislocations) are the result of direct or indirect trauma with the arm forced into abduction and external rotation.
The position of the inferior glenohumeral ligament (IGHL), which is the most important ligament and the strongest limits the anterior/inferior subluxation. The IGHL is a sling-like structure with two bands: the anterior band, which is stronger and thicker, and the posterior band. The inferior glenohumeral ligament originates from the anterior and posterior glenoid rim and labrum. The anterior band, which is an important structure of the IGHL is attached to the anatomical neck of the humerus. It limits anterior translation in abduction and external rotation. The IGHL fails at three points: the glenoid labrum, the midsubstance, and at the humeral insertion (called the HAGL lesion). The IGHL provides stability needed to keep the head of the humerus in the glenoid (similar to a person resting in a hammock).
There are several lesions associated with shoulder dislocations. In the elderly, above the age of 50, there may be a rotator cuff tear. Normally, there is a Bankart lesion (common). An avulsion of the anterior inferior labrum from the glenoid. A Hill-Sachs lesion may occur with anterior dislocation of the shoulder. The HAGL lesion is rare and more severe. It has a high recurrence rate of redislocation. A HAGL lesion may be associated with other shoulder pathology and it may be overlooked. It is a difficult diagnosis. It is becoming recognized as a cause of recurrent shoulder instability. Look for other associated injuries such as the: rotator cuff, labrum, humeral head, and subscapularis. The subscapularis may be involved with medial dislocation of the biceps tendon.
The provider may need an MRI arthrogram for the diagnosis. An MRI arthrogram is the best study (look for T2 coronal image). The “U” shaped pouch becomes “J” shaped. The MRI will show discontinuity of the IGHL attachment on the humerus with leakage of the dye. The physician should look at the axillary recess. It will become abnormal due to avulsion of the IGHL. Failure of the IGHL at the humeral insertion is not common (less than 10%). The capsule and ligaments are ripped off from the inferior humeral neck and not from the glenoid. An open surgical repair may be better for this lesion.