PMID- 15454105
OWN - NLM
STAT- MEDLINE
DCOM- 20050202
LR  - 20071114
IS  - 8756-3282 (Print)
IS  - 1873-2763 (Linking)
VI  - 35
IP  - 4
DP  - 2004 Oct
TI  - Sexual dimorphism of the femoral neck during the adolescent growth spurt: a 
      structural analysis.
PG  - 973-81
AB  - Before puberty, there are only small sex differences in body shape and 
      composition. During adolescence, sexual dimorphism in bone, lean, and fat mass 
      increases, giving rise to the greater size and strength of the male skeleton. The 
      question remains as to whether there are sex differences in bone strength or 
      simply differences in anthropometric dimensions. To test this, we applied hip 
      structural analysis (HSA) to derive strength and geometric indices of the femoral 
      neck using bone densitometry scans (DXA) from a 6-year longitudinal study in 
      Canadian children. Seventy boys and sixty-eight girls were assessed annually for 
      6 consecutive years. At the femoral neck, cross-sectional area (CSA, an index of 
      axial strength), subperiosteal width (SPW), and section modulus (Z, an index of 
      bending strength) were determined, and data were analyzed using a hierarchical 
      (random effects) modeling approach. Biological age (BA) was defined as years from 
      age at peak height velocity (PHV). When BA, stature, and total-body lean mass (TB 
      lean) were controlled, boys had significantly higher Z than girls at all maturity 
      levels (P < 0.05). Controlling height and TB lean for CSA demonstrated a 
      significant independent sex by BA interaction effect (P < 0.05). That is, CSA was 
      greater in boys before PHV but higher in girls after PHV. The coefficients 
      contributing the greatest proportion to the prediction of CSA, SPW, and Z were 
      height and lean mass. Because the significant sex difference in Z was relatively 
      small and close to the error of measurement, we questioned its biological 
      significance. The sex difference in bending strength was therefore explained by 
      anthropometric differences. In contrast to recent hypotheses, we conclude that 
      the CSA-lean ratio does not imply altered mechanosensitivity in girls because 
      bending dominates loading at the neck, and the Z -lean ratio remained similar 
      between the sexes throughout adolescence. That is, despite the greater CSA in 
      girls, the bone is strategically placed to resist bending; hence, the bones of 
      girls and boys adapt to mechanical challenges in a similar way.
FAU - Forwood, Mark R
AU  - Forwood MR
AD  - Department of Anatomy and Developmental Biology, School of Biomedical Sciences, 
      The University of Queensland, Brisbane, Queensland, 4072 Australia. 
      m.forwood@uq.edu.au
FAU - Bailey, Donald A
AU  - Bailey DA
FAU - Beck, Thomas J
AU  - Beck TJ
FAU - Mirwald, Robert L
AU  - Mirwald RL
FAU - Baxter-Jones, Adam D G
AU  - Baxter-Jones AD
FAU - Uusi-Rasi, Kirsti
AU  - Uusi-Rasi K
LA  - eng
GR  - AR44655/AR/NIAMS NIH HHS/United States
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PT  - Research Support, U.S. Gov't, P.H.S.
PL  - United States
TA  - Bone
JT  - Bone
JID - 8504048
SB  - IM
MH  - Adolescent
MH  - Child
MH  - Female
MH  - Femur Neck/*anatomy & histology/*growth & development
MH  - Humans
MH  - Linear Models
MH  - Male
MH  - Models, Biological
MH  - *Sex Characteristics
EDAT- 2004/09/30 05:00
MHDA- 2005/02/03 09:00
CRDT- 2004/09/30 05:00
PHST- 2004/03/30 00:00 [received]
PHST- 2004/06/02 00:00 [revised]
PHST- 2004/06/09 00:00 [accepted]
PHST- 2004/09/30 05:00 [pubmed]
PHST- 2005/02/03 09:00 [medline]
PHST- 2004/09/30 05:00 [entrez]
AID - S8756328204002583 [pii]
AID - 10.1016/j.bone.2004.06.005 [doi]
PST - ppublish
SO  - Bone. 2004 Oct;35(4):973-81. doi: 10.1016/j.bone.2004.06.005.