AbstractBackground: The glenohumeral joint is the articulation between the head of the humerus and the glenoid fossa of the scapula, the latter being deepened and extended by the triangular fibrocartilaginous glenoid labrum attached peripherally to the margin of the glenoid fossa. The glenoid labrum plays an important role in glenohumeral joint stability, as well as in helping to protect the articular cartilage. Yet despite this, there is little known regarding its anatomical details, while in the clinical literature few studies have clearly demonstrated its blood and nerve supply.
Aims: The aims of this study are: (I) identify the detailed blood supply of the glenoid labrum macroscopically and histologically; (II) evaluate the mode of the attachment of the glenoid labrum to the glenoid fossa macroscopically and histologically and describe its anatomical variation, including sublabral foramen and Buford complex; (III) assess the shape and dimensions of the glenoid fossa; (IV) assess the shape, thickness and depth of the glenoid labrum; (V) investigate the mode of attachment of the long head of biceps brachii and triceps to the glenoid labrum; (VI) identify the attachment of the fibrous capsule to the glenoid labrum; (VII) evaluate the attachment of the glenohumeral ligament to the glenoid labrum; and (VIII) evaluate the nerve fibres associated with the glenoid labrum.
Materials and methods: 140 formaldehyde embalmed shoulders from 30 males and 40 females were dissected. The first part of the study included macro and microdissection of (i) all muscles surrounding the glenohumeral joint, (ii) the axillary artery and its branches from their origins throughout their distribution, (iii) the glenohumeral ligaments and fibrous capsule. The second part included measurements taken to (i) the site of origin and thickness of the superior, middle and the anterior and posterior bands of the inferior glenohumeral ligaments, (ii) the type of attachment of the long head of biceps, (iii) the glenoid labrum appearance, consistency and attachment, (iv) the glenoid labrum depth and thickness at the superior (12 o’clock), anterior (3 o’clock), inferior (6 o’clock) and posterior (9 o’clock) regions, (v) the sublabral foramen, (vi) the sublabral recess, (vii) Buford complex, (viii) shape of the glenoid fossa, (ix) the length, width and length at the greatest width of the glenoid fossa with the glenoid labrum attached, (x) the type of the glenoid notch, (xi) attachment of the long head of triceps, and (xii) attachment of the fibrous capsule. The third part was histological investigation of the blood vessels associated with the glenoid labrum, using haematoxylin and eosin stain, and nerve fibres using silver nitrate and immunohistochemistry.
Results: The blood supply of the glenoid labrum by regions is as follows: the superior and anterosuperior regions from the ascending glenoid and suprascapular arteries as well as muscular branches from subscapularis and supraspinatus; the anteroinferior and inferior regions from periosteal branches of the circumflex scapular and inferior glenoid arteries, with the latter being a branch from either the posterior circumflex humeral, circumflex scapular or subscapular artery, as well as muscular branches from triceps and subscapularis; the posteroinferior and posterosuperior regions from periosteal branches from the suprascapular artery, muscular branches from teres minor and infraspinatus and occasionally an ascending branch from the circumflex scapular artery giving periosteal and direct branches to these regions as well as branches from the anterior and posterior circumflex humeral arteries which pierce the capsule anterosuperiorly, anteroinferiorly, inferiorly and posteroinferiorly supplying the anatomical neck, some of which also supply the labrum via the fibrous capsule. In addition, as the glenoid labrum is anchored to the underlying bone it receives a blood supply from the underlying bone and periosteum. Histologically, the glenoid labrum is fibrocartilaginous becoming more fibrous in its periphery. The whole of the glenoid labrum is vascular with the anterosuperior aspect having a rich blood supply. By using a silver nitrate stain and immunohistochemistry there are free sensory nerve fibres in the glenoid labrum. No mechanoreceptors were observed. A sublabral foramen was found in 28.57% being slightly more so in males and also more common on the right than the left side in both genders. A Buford complex was seen in 1.42% of specimens. With regards to a sublabral recess, type I was the most commonly seen followed by type II. Regarding the attachment of the long head of biceps to the glenoid labrum, types I and II were the most common. The glenoid fossa was pear-shaped in 70% and oval in 30%. A bare spot was observed in 80.71% of shoulders, being more common in males than females and significantly longer and wider in males. The superior glenohumeral ligament was observed in all specimens and the middle glenohumeral ligament in 98.57%. The anterior band of the inferior glenohumeral ligament was found in all specimens, while the posterior band was present in 79.28%.
Conclusion: The glenoid labrum is fibrocartilaginous being more fibrous in the periphery. It has rich blood supply from an ascending glenoid, circumflex scapular, anterior and posterior circumflex humeral, suprascapular, muscular as well as periosteal and cortical arteries, which enables its successful re-attachment. Using silver nitrate and immunohistochemistry this study is the first to confirm the existence of sensory nerve fibres within the substance of the glenoid labrum.
|Date of Award
|Roger Soames (Supervisor) & Paul Felts (Supervisor)