Bone strength and its determinants in pre- and early pubertal boys and girls

Macdonald, Heather, Kontulainen, Saija, Petit, Moira, Janssen, Patricia and McKay, Heather (2006) Bone strength and its determinants in pre- and early pubertal boys and girls. Bone, 39 3: 598-608. doi:10.1016/j.bone.2006.02.057


Author Macdonald, Heather
Kontulainen, Saija
Petit, Moira
Janssen, Patricia
McKay, Heather
Title Bone strength and its determinants in pre- and early pubertal boys and girls
Journal name Bone   Check publisher's open access policy
ISSN 8756-3282
1873-2763
Publication date 2006-09
Sub-type Article (original research)
DOI 10.1016/j.bone.2006.02.057
Volume 39
Issue 3
Start page 598
End page 608
Total pages 11
Place of publication New York
Publisher Elsevier Science
Language eng
Subject 1103 Clinical Sciences
Abstract Higher fracture rates in women than men may be related to a sex difference in bone strength that is thought to emerge during growth. However, sexual dimorphism in bone strength and the determinants of bone strength in boys and girls are not well understood. Thus, our objectives were to (1) compare tibial bone strength and its components (geometry and density) between pre- and early pubertal boys and girls and (2) identify the contribution of muscle cross-sectional area and other modulating factors to bone outcomes. We used pQCT to assess the distal tibia (8%) and tibial midshaft (50%) in 424 Asian and Caucasian pre- and early pubertal boys and girls. Our primary outcomes were bone strength index (BSI, mg2/mm4) at the distal tibia and strength strain index (SSI, mm3) at the midshaft.We also assessed components of bone strength including bone geometry [total (ToA) and cortical (CoA) cross-sectional areas, mm2] and total (ToD, mg/cm3) and cortical (CoD, mg/cm3) density.We used ANCOVA to compare bone outcomes between boys and girls in each maturity group (PRE or EARLY pubertal by Tanner stage) and multiple regression to evaluate the contribution of muscle cross-sectional area (MCSA,mm2 by pQCT), maturity, ethnicity, physical activity, dietary calcium, and vertical jump height to bone outcomes. After adjusting for tibial length and MCSA, bone strength indices were 6–15% (P < 0.05) greater in PRE and EARLYboys compared with PRE and EARLY girls. The sex difference in bone strength was due largely to greater bone areas (4–6%) in boys. At the distal tibia ToD was significantly greater in PRE boys (6%, P < 0.001) compared with PRE girls and at the midshaft CoD was slightly greater in both PRE and EARLY girls (1%, P = 0.01). After adjusting for tibial length, MCSAwas the primary explanatory variable of tibial bone geometry and strength in both sexes accounting for 10–16% of the variance. The influence of maturity, ethnicity, physical activity, and dietary calcium on pQCT bone outcomes was small and was both site- and sex-specific. Sexual dimorphism in tibial bone strength is evident in prepuberty. Our results are consistent with a functional model of bone development in which bone adapts its geometry and strength to withstand challenges from muscle forces during growth
Keyword pQCT
Bone strength
Bone geometry
Bone density
Muscle cross-sectional area
Puberty
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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Created: Mon, 16 Mar 2009, 15:42:44 EST by Alexandra Cooney on behalf of School of Human Movement and Nutrition Sciences