What is in the osteoarthritic bone marrow lesion?
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Embargoed until: 5555-01-01
Reason: Publisher archiving policy not established
DOI
10.3389/978-2-88919-974-7
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What is in the osteoarthritic bone marrow lesion? Nidhi Sofat1, Maureen Arora2, Anasuya Kuttapitiya1, Alan Boyde2 1St George’s, University of London, London, UK 2Dental Physical Sciences, Queen Mary University of London, London E1 4NS, UK Introduction: Bone marrow lesions (BML) are identified by MRI imaging in many osteoarthritis (OA) patients. Comparatively, few attempts have been made to correlate clinical imaging with histopathology, with changes involved in these regions needing further clarification. Preparation for standard histology using decalcification, wax embedding and sectioning loses the mineral content and 3D context. We hypothesised that approaches using scanning electron microscopy (SEM) of large tissue blocks embedded in PMMA might give more intact tissue, new insights and better correlation with clinical imaging. Materials and Methods: Distal femur/proximal tibia samples were obtained at knee replacement from three OA cases after MRI imaging of BML with full informed consent. Tissue pieces were dehydrated in ethanol and embedded in PMMA. Block surfaces were trimmed and polished to 4000 grit silicon carbide paper. To study mineral content only, they were examined without coating by 20kV BSE SEM imaging at 50Pa chamber pressure. To study soft tissue histology, blocks were stained using iodine vapour before SEM. Results: BSE SEM of iodine stained blocks provided good imaging of all soft tissue phases. Problems were encountered near surfaces cut during surgery due to bone fragment impaction into marrow spaces, but was less of a problem near and in the BML sites, which was solved by re-cutting the block surfaces normally to generate section planes further from this initial damage, with the further advantage that both cut surfaces could be imaged simultaneously. Most normal bone marrow was adipocytic with adipocytes the major bone lining cells, frequently making and moulding trabecular excrescences. Bone volume fraction was starkly reduced in BML areas, with marrow replaced by: (1) nothing recognisable morphologically (2) dense fibrous connective tissue or (3) hyaline cartilage or fibrocartilage. Areas of aggressive resorption were found at the periphery of BML patches and areas of calcified cartilage so deep within the bone that they could not be explained by impaction from the joint surfaces, but must have arisen by mineralisation of cartilage formed deep within the bone organ. Conclusion: We provide 2.5D or 3D SEM histology correlated with 3D clinical imaging to demonstrate what is in the BML lesion. P024 page 93 Bone Research Society Annual Meeting 29 June- 1 July 2016 Liverpool DOI: 10.3389/978-2-88919-974-7 ISBN: 978-2-88919-974-7 Published in Frontiers in Endocrinology