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    ASBMR 2012 Annual Meeting

    Proximal Femoral Cortical Thickness in Postmenopausal Women Shows Highly Localised Significant Asymmetry

    Category: Bone Biomechanics and Quality (Basic)

    Poster Sessions, Presentation Number: SA0061
    Session: Poster Session I and Poster Tours
    Saturday, October 13, 2012 11:00 AM - 1:00 PM, Minneapolis Convention Center, Discovery Hall-Hall B

    * Tom Turmezei, University of Cambridge, UNITED KINGDOM, Graham Treece, University of Cambridge, United Kingdom, Andrew Gee, University of Cambridge, United Kingdom, Carol Tonkin, University of Cambridge, United Kingdom, Madhavi Vindlacheruvu, Cambridge University Hospitals NHS Foundation Trust, United Kingdom, Karen Blesic, University of Cambridge, United Kingdom, Kenneth Poole, University of Cambridge, UNITED KINGDOM

    Background

    Establishing focal skeletal left-right difference is important for anthropological study, understanding adaptation to strain and the clinical investigation of bone. Asymmetry is not only well established in the human skeleton but, given that bone exhibits functional adaptation, is also to be expected. Differences in the lower limb are reported to be of smaller magnitude than in the upper limb, with the lower limb also mirroring the usual pattern of upper limb right-sided dominance. Until now, only selective focal or summative regions have been analysed. Dual energy X-ray absorptiometry of the proximal femora has shown either a left bias or no difference in areal bone mineral density, however individual left-right differences of up to 26% have been reported.

    Methods

    Cortical thickness maps were created of the proximal femora from clinical CT data of 197 postmenopausal women aged 73±7 yrs (mean±sd) combined from 3 cohorts: 48 from the FEMCO study (75±8 yrs), 80 from the FREEDOM study (74±5 yrs) and 69 from the EUROFORS study (70±7 yrs). All data were taken from the study baseline prior to any intervention. After registration of each bone to an average (right) femur shape, statistical parametric mapping was used to determine sites of significant differences in mean cortical thickness between sides.

    Results

    We identified highly focal differences between left and right, including a vertical band of significantly thicker cortex along the load-bearing anteromedial aspect of the right proximal femoral shaft. Several smaller patches of cortex at the inferomedial femoral neck and the greater trochanter were also significantly different between sides, some thicker on the left (fig. 1). Results were validated across each of the study subgroups.

    Discussion

    Highly localised and significant left-right differences were detected in the cortical thickness of the proximal femora of postmenopausal women. The vertical band of increased thickness on the right correlates with the point of maximal stress in the early and mid-gait cycle, suggesting that side differences may be related to gait asymmetry. There is also a high thickness gradient in this region, and so findings could represent widening of thicker regions around the cortex from mineral redistribution in response to load-bearing. These results reinforce the importance of cortical thickness measurement location since dimensions derived from planar imaging can hide significant local fluctuations.

    Disclosures: K. Poole, Co-inventor of a related patent: Other. G. Treece, Co-inventor of a related patent: Other.

    * Presenting Authors(s): Tom Turmezei, University of Cambridge, UNITED KINGDOM

    Attachments

    Figure 1