ALSPA, HAGL,GLAD & BANKART

The 3 glenohumeral ligaments (GHLs) represent condensations of the shoulder capsule.The posterior capsule always inserts into the posterior labrum. The anterior capsule has a more variable medial insertion  on the labrum (47%) or glenoid neck (49%).The most important structure stabilizing the shoulder—one that limits gross anterior-inferior subluxations and dislocation—is the IGHL. This ligament forms a sling with discrete anterior and posterior bands. It is lax when the humerus is in the neutral position, and it allows normal shoulder movement. The ligamentous complex becomes taut in abduction and external rotation and, thus, stabilizes the joint at the end range of shoulder movement in the abduction external rotation (ABER) direction.

During a dislocation, forces exceed the threshold that the ligamentous complex can bear, leading to tears or stretching. This may lead to laxity and instability. Failure of the IGHL can occur at the insertion site (40%), in the ligamentous substance (35%), and at the humeral insertion site (25%).Bankart lesions represent failure of the IGHL at the glenoid insertion. IGHL capsule laxity represents intrasubstance ligamentous failure, whereas humeral avulsions of the GHL (HAGL) represent failure of the IGHL at its humeral insertion

A Bankart lesion is the most common lesion in anterior instability. The tear is usually large enough to involve not only the labrum, where the anterior band of the IGHL inserts, but also the middle labrum and, sometimes, the superoanterior labrum 

in a Bankart lesion, the scapular periosteum ruptures as the labroligamentous ligaments are avulsed from the glenoid. In Bankart variants, the scapular periosteum remains intact relative to the labroligamentous complex. If the labroligamentous complex is displaced medially and shifted inferiorly, rolling up on itself, the lesion is called an ALPSA lesion. An ALPSA lesion is associated with more severe injury.In the ALPSA, the labral fragment remains attached to the periosteum of the scapular margin and can be tethered in this abnormal position, increasing the likelihood further medial displacement and of re-dislocation.

A GLAD lesion is a tear of the anteroinferior labrum (nondisplaced) with avulsion of the adjacent glenoid cartilage. A glenoid chondral defect is therefore visualized. The labrum is not detached, and there is no capsular stripping. This lesion is clinically stable. The mechanism is glenohumeral impaction in the ABER position. Clinically, these patients complain of pain rather than instability. The lesion can be treated with arthroscopic debridement without need for a stabilization procedure