The ovine calcaneus: a useful model for fragility fractures of the hip?

Abstract

Event Abstract Back to Event The ovine calcaneus: a useful model for fragility fractures of the hip? N Loveridge1*, J Power1, J Reeve1, M Warren2, M Doube3 and A Goodship2 1 University of Cambridge, Orthopaedic Research Unit and Dept of Medicine, United Kingdom 2 Royal Veterinary College, United Kingdom 3 Imperial College, United Kingdom Cases of fragility hip fracture, show excessive loss of cancellous connectivity, cortical thinning and increased porosity. While alterations in mechanical loading are considered to play a key role, currently there is no satisfactory animal model, which mimics the essential biomechanics of the human femoral neck and allows the assessment of both intra-cortical and cancellous bone turnover. The ovine calcaneus is a short bone cantilever loaded in bending with a defined cancellous architecture and cortices that undergo intra-cortical adaptation to habitual tensile and compressive loads. We hypothesised that this bone would respond to decreases in loading with changes in both cancellous and cortical bone so providing an appropriate model to study fragility fractures of the hip. Using external fixators to protect the left calcaneus of ewes (6/group) from normal levels of load related strain we analysed the consequent changes in cortical and cancellous bone after 4, 8 & 16 weeks using the contra-lateral bone as a control.{BR}Fixation reduced maximum local loads by 50% (free: 95.9 microstrain±24.4 (SD); fixed: 48.0±9.9 (SD)) but the marked individual patterning between bones from the same animal was unaffected. Bone volume and BV/TV reduced over time in the left (load protected) but not the right (control) calcaneus (BV: Left -34.72mm3/wk p=0.0002; Right: -4.83mm3/wk, p=0.555 p<0.0001; BV/TV: Left -0.0069/wk; Right: - 4.1522e-5/day, p=0.80). {BR}Trabecular thickness, and number, but not spacing, was affected (Tb.Th: Left -0.133mm/wk, p<0.0001; Right: +0.0084mm/wk, p=0.657; 1/TbN: Left: +0.0133/wk, p<0.0001; Right: +52.87e-5/wk, p=0.75). Both SMI (Left +0.437/wk p<0.0001; Right: -0.11/wk, p=0.339) and aniostropy (Left -0.442/wk p<0.0001; Right: +0.0149mm/wk, p=0.657) were altered by under-loading.{BR}The %cortical area (diff; - 10.6%, p=0.012) and cortical thickness (diff -0.13mm p=0.018) were reduced in the under-loaded calcaneus at 16 weeks. Mean canal area was increased (diff +62.5±15um2; p=0.02) but canals/bone area was unchanged.{BR}In conclusion, under-loading the ovine calcaneus resulted in changes in cancellous and cortical bone, which mimicked most of those seen in fragility fractures of the human femoral neck. This suggests that this model is suitable to further explore hypotheses related to the causes of intracapsular hip fracture and the development of new prevention strategies. Keywords: Bones, Bone Research Conference: 2011 joint meeting of the Bone Research Society & the British Orthopaedic Research Society, Cambridge, United Kingdom, 27 Jun - 29 Jun, 2011. Presentation Type: Poster Topic: Abstracts Citation: Loveridge N, Power J, Reeve J, Warren M, Doube M and Goodship A (2011). The ovine calcaneus: a useful model for fragility fractures of the hip?. Front. Endocrinol. Conference Abstract: 2011 joint meeting of the Bone Research Society & the British Orthopaedic Research Society. doi: 10.3389/conf.fendo.2011.02.00040 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 30 Sep 2011; Published Online: 30 Sep 2011. * Correspondence: Dr. N Loveridge, University of Cambridge, Orthopaedic Research Unit and Dept of Medicine, Cambridge, United Kingdom, nl10003@cam.ac.uk Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers N Loveridge J Power J Reeve M Warren M Doube A Goodship Google N Loveridge J Power J Reeve M Warren M Doube A Goodship Google Scholar N Loveridge J Power J Reeve M Warren M Doube A Goodship PubMed N Loveridge J Power J Reeve M Warren M Doube A Goodship Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.