Anatomical, functional and biomechanical review of the glenoid labrum

Abstract

The glenohumeral joint is the most mobile joint in the human skeleton, supported by both active and passive stabilisers. As one of the passive stabilisers, the glenoid labrum has increasingly been recognised to play an important role in stability of the glenohumeral joint, acting to maintain intraarticular pressure, centralise the humeral head and contribute to concavity-compression stability. Several studies have investigated the macro- and micro-anatomical features of the labrum as well as its biomechanical function. However, in order to better understand the role of the labrum and its mechanics, a comprehensive anatomical, functional and biomechanical review of these studies is needed. Therefore, this article reviews the current literature detailing anatomical descriptions of the glenoid labrum, with an emphasis on its function(s) and biomechanics, as well as its interaction with neighbouring structures. The intimate relationship between the labrum and the surrounding structures was found to be important in glenohumeral stability, which owes further investigation into the microanatomy of labrum to better understand this relationship.

Keywords: anatomy; biomechanics; glenohumeral joint; glenohumeral ligaments; glenoid labrum.

FIGURE 1

Anatomical divisions of the glenoid fossa. A lateral view of a right glenohumeral joint (with the humerus removed) illustrating the anatomical and the ‘o'clock’ based localisation methods commonly used to subdivide the labrum. The 12 ‘o'clock’ position is used to identify the position of the superior labrum. Illustration adapted from Dekker et al. (2020)

FIGURE 2

Schematic overview of the positioning, thickness and height of the labrum. A cross section of the triangular labrum (L) attaching on both the glenoid bone (B) and the articular cartilage (AC) illustrating the positioning, thickness and height of the glenoid labrum, as described in Alashkham et al. (2019)

FIGURE 3

Schematic overview of the glenoid fossa and related structures. Lateral view of a right glenoid fossa of the scapula showing the articular cartilage in the middle of the glenoid fossa surrounded by the glenoid labrum on its rim. The subscapular bursa is located anterior to the tendon of the long head of biceps brachii (LHB), in close proximity to the superior glenohumeral ligament (SGHL) and middle glenohumeral ligament (MGHL). The inferior glenohumeral ligament can be found inferiorly, highlighting its different segments: the anterior band (A‐IGHL), axillary pouch, and the posterior band (P‐IGHL). Illustration adapted from Dekker et al. (2020)

FIGURE 4

Schematic illustration of biomechanical forces impacting on the glenoid labrum. A cross section of the glenoid bone (B) showing the capsule (C), labrum (L), and articular cartilage (AC), as well as the fibrocartilaginous transition zone, illustrating the role that the glenoid labrum can play in stress dissipation on the angled fibres of the capsule and labrum. The transfer of forces (arrows) is illustrated in the right panel, when force is applied to the capsule. The fibrocartilage area of the labrum limits flexion of the labrum towards the articular cavity, mediated by the low compressibility of the fibrocartilage zone