Examining the relationship between ultrastructural features and tensile properties in joint and non joint regions of peripheral nerve

Sarah Mason

    Research output: ThesisDoctoral Thesis

    Abstract

    Peripheral nerve repair is often compromised by a failure to restore the biomechanical integrity of a damaged nerve. An understanding of the mechanical architecture that underpins the tensile properties of peripheral nerves, in particular their ability to bend and stretch during movement, is an important consideration in the design of tissue engineered repair conduits and other repair approaches. Mechanical features are distributed heterogeneously within rat nerve tissue, with compliance increased at articulations. This study sought to explore which ultrastructural features of the rat peripheral nerve are likely to be associated with this biomechanical heterogeneity, to examine whether these features are present in the human peripheral nerve and to conduct pilot investigations into the feasibility of assessing the mechanical behaviour of joint and non joint regions of nerve in human volunteers. The anatomical features of fascicle number, nerve cross sectional area and perineurium thickness were assessed in joint and non joint regions of rat median and sciatic nerve. Regional comparisons of collagen, elastin and beta spectrin were also made at these joint and non joint locations. Collagen fibril diameter in rat and human nerves was analysed using transmission electron microscopy and the number density of fibrils examined. Ultrasound was used to image the dynamic human nerve in a pilot study. There was no difference in the amount of collagen or elastin in joint and non joint regions of rat peripheral nerve and beta spectrin was present at both locations. Cross sectional area, degree of fasciculation and perineurium thickness were similar in joint and non joint areas. A population of collagen fibrils with significantly reduced diameter was found at the joint region of the rat median nerve that corresponds to the location of increased compliance in this tissue, though this pattern was not observed in the rat sciatic nerve. The number density of collagen fibrils was significantly increased at joint regions of the median nerve, indicating a greater number of thinner fibrils at this location. Examination of cadaveric human median nerves revealed a similar trend towards regional variation of collagen fibril diameter, with thinner fibrils at the joint regions compared to the non joint, particularly at the elbow, though the ulnar and radial nerves did not show a similar pattern. When the human median nerve was imaged using high resolution sonography, measurement of the displacement of the nerve at joint and non joint locations was achieved with the use of a novel speckle tracking algorithm, suggesting that with future development of this method it may be possible to measure strain. - See more at: http://ethos.bl.uk/OrderDetails.do?did=6&uin=uk.bl.ethos.551623#sthash.HxhVGbri.dpuf
    Original languageEnglish
    Awarding Institution
    • The Open University
    Publisher
    Publication statusPublished - Dec 2011

    Keywords

    • Peripheral nerves
    • Collagen fibril
    • Nerve biomechanics
    • High resolution sonography

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