Saudi Cultural Missions Theses & Dissertations
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Item Restricted Anatomical, biomechanical and histological evaluation of the glenoid labrum(The University of Edinburgh, 2024-04-26) Almajed, Yousef Abdulaiz M; Alashkham, AbduelmenemThe glenoid labrum is an integral part of the highly mobile glenohumeral joint. Labral injury can be detrimental to the movement and function of the shoulder. Therefore, an in-depth investigation of glenoid labrum microanatomy may improve our understanding of its roles and functions in the glenohumeral joint. This project aimed to explore the (1) composition and attachment, (2) vascularity, and (3) innervation of the glenoid labrum. Labral degenerative changes were also assessed relative to the changes in labral neurovascularity that were observed. Sixteen cadaveric shoulders were obtained under the supervision of a licensed anatomist from the Department of Anatomy, University of Edinburgh and in accordance with the Human Tissue Act (Scotland) of 2006. After dissection, the glenoid, including the labrum and the attachments of its associated structures, was segmented into eight regions and processed for histological analysis. Three histological stains were utilised to evaluate the composition of the labrum and assess its attachments. General labral morphology was first assessed in haematoxylin and eosin-stained sections. This was followed by staining with toluidine blue to assess the total and percentage of the labral area occupied by proteoglycans as an indirect measure of its capacity to accommodate a compressive load. Finally, Verhoeff-Van Gieson stain was used to localise elastin fibres within the labral cross-section. Labral vascularity was assessed immunohistochemically using an anti-alpha-smooth muscle actin antibody and evaluated quantitatively by determining the vascular count, vascular density, and blood vessel distribution within the labrum. Labral innervation was assessed immunohistochemically with an anti-p75 antibody that facilitated the quantitative analysis of nerve count and nerve density. Nerve types were identified following the modified Hagert (2008) classification. Degenerative changes detected in the labrum were assessed following a histopathologic grading system described by Pauli et al. (2011). After microanatomical quantification, differences in proteoglycan content, vascularity, and innervation were assessed across various labral regions, and correlations of labral vascularity and innervation to proteoglycan area and proteoglycan percentage were determined. Finally, labral vascularity and innervation were also evaluated in labral tissues exhibiting various grades of degeneration. The glenoid labrum is connected to the glenoid bone via a fibrocartilaginous attachment that includes a fibrocartilaginous transition zone that links the bone to the fibrous labrum. Elastin fibres exhibited a distinct localisation within the labrum, including the capsular attachment, between large collagen bundles and within the fibrocartilaginous regions. Blood vessels and nerves were identified in all labral regions. Four types of mechanoreceptor nerve endings were identified within the labrum, including Ruffini corpuscles, Pacini corpuscles, Golgi-like nerve endings and unclassified corpuscles. The labral sections ranged from normal to moderately degenerated; no severely degenerated labra were identified. The analysis revealed significant variation across all labral regions and a significant inverse correlation between vascularity and innervation with proteoglycan content. However, there were no significant differences in vascularity and innervation across the degeneration spectrum. In conclusion, the glenoid labrum was vascularised and innervated throughout its circumference, but exhibited significant microanatomical variations that were linked to compressive load accommodation properties. The different types of nerve endings found in the labrum suggest that the labrum contribute to the sensorimotor function of the glenohumeral joint. Whilst the degree of degeneration had no apparent influence on labral vascularity or innervation, a larger sample size will be needed to substantiate these findings. The results of this study will lead to improvements in our understanding of the microanatomy of the glenoid labrum and have important implications for shoulder function and stability. The findings may also provide critical insights into methods that may be used for injury management and new rehabilitation strategies.34 0Item Restricted Anatomic, Histologic and Histomorphometric Analysis of the Acetabular Labrum and its Enthesis(The University of Edinburgh, 2024-04-19) Alomiery, Abdulaziz; Alashkham, Abduelmenem; Hall, Andrew; Gillingwater, TomThe acetabular labrum is a fibrocartilaginous tissue attached to the acetabular rim of the hip joint. It plays a vital role in maintaining both static and dynamic hip joint stability, with multiple associations to pain sensation, proprioception, and various hip joint disorders. Various traumatic and pathological conditions can compromise the structural integrity of the labral body and its attachment, leading to disruptions in hip joint stability. The localisation of the labrum within a large load-bearing joint has led to disparities in its structural and functional characteristics at the cross-sectional level. These disparities are localised within distinct labral zones (i.e., inner and outer zones), which are commonly attributed to the functional adaptation of each zone to mechanical loads. Despite the labrum's critical role in hip joint function, its intricate micro-anatomical differences, both within its main body and at its attachment to bone, have remained largely unexplored in the current research. The primary objective of this project was to provide a detailed investigation of several micro-anatomical aspects of the labrum, encompassing labral innervation, vascularity, attachment features, degrees of degenerative changes, and levels of tears. The aim was placed on understanding the effects of labral morpho-functional zones on the distribution dynamics of these micro-anatomical characteristics. Secondly, this project also assesses the relationship between labral vascularity and innervation and their potential implications on labral healing and degeneration. Human tissue was obtained from 9 embalmed cadavers, comprising a total of 16 hemipelves (10 males and 6 females) with an average age of 80 years. Each hip was divided into 8 distinct regions, resulting in a total of 128 regional segments. The histological investigations produced a total of 742 tissue sections, which were utilised in a variety of histological and immunohistochemical staining techniques. Initially, a systematic zone-specific approach for labral assessment was developed to achieve a thorough understanding of the distribution dynamics of labral histologic and histopathologic characteristics across different zonal territories. The histopathologic evaluation of the labrum revealed a significant increase in the severity of multiple degenerative features, which were predominantly concentrated in the inner labral zone near the articular surface. These degenerative changes encompassed alterations in matrix proteoglycan content, cellularity, collagen organisation, and surface, including the lamellar layer. Immunohistochemical analysis and quantification of labral neuro-vascularity revealed a significantly higher concentration in the outer labral zone, near the joint capsule, with notably reduced neuro-vascularity in the inner zone. The analysis of sensory nerve endings revealed distinct distribution patterns for proprioceptive and nociceptive innervations within the labrum. Various types of sensory corpuscles (including Pacini, Ruffini, Golgi, and unclassified corpuscles), along with free nerve endings (both perivascular and non-perivascular), were significantly more concentrated within the outer labral zone. The histological examination of the labral enthesis structure and morphology unveiled a fibrocartilaginous type of attachment. Notably, the attachment of the labrum to the bone exhibited marked differences in structural morphology between the inner and outer zones. The histopathologic and histomorphometric analysis of the enthesis’s layers, including calcified fibrocartilage region (CFC), tidemark (TM) and cement line (CL), revealed a significantly more developed and compact attachment in the inner zone. In contrast, the outer enthesis displayed a notably weaker anchorage, characterised by less defined entheseal features, a higher frequency of entheseal and cortical bone micro-damage, and a greater incidence of inflammatory and degenerative changes. The labral morpho-functional zones play a significant role in shaping multiple micro-anatomic features of the labrum, affecting the distribution of degeneration processes and labral healing capability. The delineation of these distinct zonal frameworks offers insights into the labrum's functional adaptation to its mechanical environment and a zone-specific vulnerability to injury and degeneration.25 0