Periarticular fiber system of the shoulder joint.

The structure and attachment of the glenoid labrum were examined from the functional point of view in 42 shoulder-joint cavities using a combination of macroscopic and microscopic techniques. The labrum continues the long tendon of the biceps as far as the ventral glenoid notch and is supplemented by a connecting band between the superior and inferior glenohumeral ligaments. In the upper quadrants, the periarticular fibers are broadly attached to the neck of the scapula and separated by a gap from the articular cartilage. In the lower quadrants, they are attached to both the neck of the scapula and the joint surface. The periarticular structures consist of bundles of parallel collagen fibers that run round the entire circumference of the cavity. The labrum, glenohumeral ligaments, and inserting tendons form a basket of fibers around the neck of the scapula, which constitutes a functional unit: the periarticular fiber system (PAFS). This acts as a tension-brace for the joint cavity and takes part in the local transmission of pressure through the cavity. Detachment of the labrum, or the labral-biceps anchor, should only be diagnosed when it can be shown that the tissue between the PAFS and the upper part of the neck of the scapula has been torn, and that the extent of the gap formation reaches laterally and caudally beyond the peripheral edge of the cartilage.