title: Investigation of sex differences in hip structure in peripubertal children.
abstract: BACKGROUND
  There is evidence that sex differences in hip structure are increased during puberty, possibly as a consequence of associated changes in body composition.
  
  
  OBJECTIVE
  The objective of the study was to explore relationships between sex, puberty, hip structure, and body composition.
  
  
  METHODS
  The design was a longitudinal birth cohort study: The Avon Longitudinal Study of Parents and Children.
  
  
  METHODS
  Participants included 3914 boys and girls (mean age 13.8 yr).
  
  
  METHODS
  Measures included dual-energy x-ray absorptiometry-derived femoral neck width (FNW), cortical thickness (CT), bending strength [cross-sectional moment of inertia (CSMI)], section modulus, buckling ratio (BR), and femoral neck and total hip bone mineral density.
  
  
  RESULTS
  FNW, CT, and CSMI were higher in boys, whereas BR was lower in girls (P<0.001). Differences in hip structure were studied according to puberty (self-completion Tanner stage questionnaires). FNW, CT, and CSMI were higher in Tanner stage IV/V vs. I/II, particularly in boys (P<0.001, puberty-sex interaction). BR was lower in Tanner stage IV/V, particularly in girls (P=0.008, puberty-sex interaction). Adjusting for height, fat mass, and lean mass resulted in differential attenuation in the sexes, such that CT attenuated by about 80% and about 40% in boys and girls, respectively (P=0.004, puberty-sex interaction for adjusted CT, Tanner stages I/II vs. IV/V). The difference in BR showed little attenuation after adjustment.
  
  
  CONCLUSIONS
  During puberty, hip-bending strength increases, particularly in boys, due to their greater FNW, reflecting changes in height, fat mass, and lean mass. In contrast, BR falls during puberty, particularly in girls, reflecting their smaller FNW relative to CT, involving mechanisms partly independent of height and body composition.
authors.affiliation: Academic Rheumatology, Clinical Science at North Bristol, University of Bristol, and Avon Orthopaedic Centre, Southmead Hospital, Bristol BS10 5NB, United Kingdom.
authors.forename: Adrian
authors.initials: A
authors.lastname: Sayers
authors.forename: Michele
authors.initials: M
authors.lastname: Marcus
authors.forename: Carol
authors.initials: C
authors.lastname: Rubin
authors.forename: Michael A
authors.initials: MA
authors.lastname: McGeehin
authors.forename: Jonathan H
authors.initials: JH
authors.lastname: Tobias
mesh_terms: D015502:Absorptiometry, Photon; D000293:Adolescent; D001823:Body Composition; D015519:Bone Density; D002648:Child; D005260:Female; D005272:Femur Neck / Q000033:anatomy & histology; D006615:Hip / Q000033:anatomy & histology*; D006801:Humans; D008297:Male; D011627:Puberty; D012727:Sex Characteristics