Reconciling Arthroscopic and Anatomic Morphology of the Humeral Insertion of the Inferior Glenohumeral Ligament

Purpose: To clarify the morphology of the humeral insertion of the inferior glenohumeral ligament (IGHL). Type of Study: Cadaveric and arthroscopic anatomic analysis. Methods: The morphology of the humeral insertion was studied in 200 nonembalmed cadavers through open dissection (100 specimens), by arthroscopy (50 specimens), or both (50 specimens). In addition, the morphology was studied in 100 living subjects with stable shoulders undergoing shoulder arthroscopy. Results: On the humeral side, the insertion of the inferior capsular fibers is usually in the form of a V, the point of which is covered by the tendon of the latissimus dorsi. When viewed intra-articularly, the inferior insertion usually gives a collar-like impression because the capsular recess is filled with frenula capsulae. Conclusions: Our description corresponds with that found in the classic literature. Our results are, however, in contrast with those of others who have observed about 50% of V-shaped insertions. This difference may be explained by the method of observation and by the small numbers of specimens studied. The form of the humeral insertion of the IGHL is linked to the formation of a supporting hammock that can accommodate the humeral head during movement as described by several authors. Clinical Relevance: We believe that the difference between arthroscopic and anatomic observation of the humeral insertion may have 2 major clinical implications. An observed tear of the frenula capsulae may not necessarily represent a humeral avulsion of the glenohumeral ligaments (HAGL). In the case of a HAGL, the capsule may have to be reattached in its V-form to adequately retension the inferior capsule.