title: Growth patterns at distal radius and tibial shaft in pubertal girls: a 2-year longitudinal study.
abstract: Bone changes, in terms of both size and BMD, were assessed longitudinally in pubertal girls. Before puberty, BMD at the distal radius declined, whereas bone size increased, suggesting that normal growing girls experience a transient period of increased bone fragility. This could explain the elevated low-trauma forearm fracture rates reported in earlier studies.
  
  
  BACKGROUND
  Longitudinal data on bone growth during puberty are sparse. Such information is needed to understand the sequence of biological changes, the physical and mechanical consequences for the growing skeleton, and the implications for later life.
  
  
  METHODS
  The geometric properties and volumetric BMD (vBMD) of the distal radius and tibial shaft were measured using pQCT in 258 pubertal girls followed over 2 years. A new hierarchical linear statistical modeling approach was used to determine true longitudinal trends.
  
  
  RESULTS
  The growth rates of cross-sectional area (CSA) and BMC of the distal radius peaked at 16 and 9 months before menarche, respectively. This growth asynchrony between bone size and mass meant that total vBMD of the distal radius declined until 1 year before menarche. At the tibial shaft, total vBMD and cortical vBMD increased monotonically without any such transient reduction. Cortical thickness increased linearly, which was accounted for mainly by bone formation at the periosteal surface before menarche, but by both periosteal and endocortical apposition after menarche. During puberty, the ratio of cortical-to-total CSA of the tibial shaft increased and that of marrow-to-total CSA decreased.
  
  
  CONCLUSIONS
  The temporal pattern of bone growth during puberty differs at the distal radius and tibial shaft. A transient decrease in vBMD, arising from asynchronous bone size and mass growth, occurs only at the radius. In the tibia, the mechanism of cortical thickening changes from periosteal apposition premenarche to both periosteal and endocortical apposition postmenarche.
authors.affiliation: Department of Health Sciences, University of Jyväskylä, Jyväskylä, Finland.
authors.forename: Qingju
authors.initials: Q
authors.lastname: Wang
authors.forename: Markku
authors.initials: M
authors.lastname: Alén
authors.forename: Patrick
authors.initials: P
authors.lastname: Nicholson
authors.forename: Arja
authors.initials: A
authors.lastname: Lyytikäinen
authors.forename: Miia
authors.initials: M
authors.lastname: Suuriniemi
authors.forename: Erkki
authors.initials: E
authors.lastname: Helkala
authors.forename: Harri
authors.initials: H
authors.lastname: Suominen
authors.forename: Sulin
authors.initials: S
authors.lastname: Cheng
mesh_terms: D000293:Adolescent; D000886:Anthropometry; D001827:Body Height; D001835:Body Weight; D015519:Bone Density; D001846:Bone Development; D001842:Bone and Bones / Q000033:anatomy & histology / Q000378:metabolism / Q000502:physiology*; D002648:Child; D003720:Densitometry; D005260:Female; D006801:Humans; D016014:Linear Models; D008137:Longitudinal Studies; D008572:Menarche; D015233:Models, Statistical; D011627:Puberty; D011884:Radius / Q000033:anatomy & histology* / Q000254:growth & development*; D013977:Tibia / Q000033:anatomy & histology* / Q000254:growth & development*; D013997:Time Factors