Characterising cortical density in the mid-tibia: Intra-individual variation in adolescent girls and boys

Cooper, D. M. L., Ahamed, Y., Macdonald, H. M. and McKay, H. A. (2008) Characterising cortical density in the mid-tibia: Intra-individual variation in adolescent girls and boys. British Journal of Sports Medicine, 42 8: 690-695. doi:10.1136/bjsm.2008.049528

Author Cooper, D. M. L.
Ahamed, Y.
Macdonald, H. M.
McKay, H. A.
Title Characterising cortical density in the mid-tibia: Intra-individual variation in adolescent girls and boys
Journal name British Journal of Sports Medicine   Check publisher's open access policy
ISSN 0306-3674
Publication date 2008-08-01
Sub-type Article (original research)
DOI 10.1136/bjsm.2008.049528
Volume 42
Issue 8
Start page 690
End page 695
Total pages 6
Place of publication London, U.K.
Publisher BMJ Group
Language eng
Subject 1106 Human Movement and Sports Science
Formatted abstract

Background: Inter-individual differences in cortical bone volumetric density (CoD), such as those related to sex, are a product of differences in remodelling rates. While cortical bone is often treated as a uniform tissue, remodelling rates also vary within individual bones. This level of adaptation has largely been overlooked in analyses of peripheral quantitative computed tomography (pQCT) images. Further, such variation in CoD has never been assessed in growing bones. We hypothesised that CoD varied significantly within the same cross-section of the mid-tibia of adolescents. We further hypothesised that due to the profound impact of oestrogen on remodelling, this variation would be different between sexes.
Methods: Subjects were 183 adolescents (99 girls and 84 boys) in grade 6 and 7 with a mean age of 12.1 years. We used age at peak height velocity to adjust for maturational differences between sexes. Image data from a mid-tibia pQCT scan of each subject were assessed regionally within eight sectors distributed about the cortex and aligned by the anterior tibial crest. We used a repeated measures general linear model to assess intra-individual variation in CoD while controlling for differences in ethnicity, maturity, height, weight, physical activity level and total cross-sectional bone area (ToA).
Results: Sector based variation in CoD was significant (p<0.001), with the anterior cortex having lower density than the posterior cortex. The largest percentage difference (anterior vsposteromedial sectors) was 12.2%. A significant sector*sex interaction (pā€Š=ā€Š0.018) was detected; however, its impact was relatively small with girls having 1.1–3.6% denser bones than boys depending on the sector (2.7% average difference).
Conclusions: The magnitude of the variation in CoD across sectors within individuals of both sex was far greater than the mean differences between the sexes. This finding indicates that the microstructural variation within the mid-tibia is detectable by pQCT and its magnitude suggests an important level of adaptation to loading.

Keyword Adolescence
Physical actitvity
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Non-UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: Excellence in Research Australia (ERA) - Collection
School of Human Movement and Nutrition Sciences Publications
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Citation counts: TR Web of Science Citation Count  Cited 15 times in Thomson Reuters Web of Science Article | Citations
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Created: Thu, 25 Mar 2010, 21:28:21 EST by Ms May Balasaize on behalf of Faculty Of Health Sciences