Histologic and scanning electron microscopic study of the glenoid labrum

Three-dimensional fibrillar architecture of the glenoid labrum and its attachment to the glenoid rim were studied in 15 cadaveric shoulders to understand the pathophysiologic condition of various shoulder diseases. The true anatomic labrum was a narrow band located at the junction of the glenoid rim and fibrous capsule and varied considerably in size and shape. A triple-layered collagen structure of the labrum was observed by scanning electron microscopy. The thin superficial layer (articular surface) was a reticulated fibrilar network. The second layer was stratified. These two layers seem to act as a bumper against impact on the humeral head. The third, main layer of the labrum consisted of bundles of the fine fibrils densely arranged almost parallel to each other and oblique to the glenoid rim. This layer appears to act as a cushion to stabilize the shoulder joint.