An anatomic study of the humeral insertion of the inferior glenohumeral capsule.

To define inferior humeral capsular anatomy better, 12 cadaveric shoulders were dissected and an inferior capsular shift was performed. Two types of inferior humeral attachments were identified. In 7 specimens, the anterior capsular insertion bifurcated at the 8-o'clock position (on a right specimen) into a superior internal fold adjacent to the articular cartilage and an inferior external fold on the humeral surgical neck. In 5 specimens, the capsular insertion did not split but inserted over a broad area on the surgical neck. In all specimens, there was a re-confluence of the two folds at the 4-o'clock position. The inferior humeral capsular attachment may extend as far as 2 cm inferior to the articular surface and can be divided into two distinct types, split and broad, each with distinct internal and external folds of the capsule. Failure to release both of these folds limits the ability to shift the capsule superiorly by tethering the capsule inferiorly.