title: Bone micro-architecture and determinants of strength in the radius and tibia: age-related changes in a population-based study of normal adults measured with high-resolution pQCT.
abstract: CONCLUSIONS
  We recruited a population-based sample of 58 males and 74 females aged 20-79 from a primary care medical practice to provide normative and descriptive data for high-resolution peripheral quantitative computed tomography (pQCT) parameters. Important effects of ageing and contrasts in the effects of sex on the micro-architecture and strength of upper and lower limb bones were revealed.
  
  
  BACKGROUND
  The advent of high-resolution pQCT scanners has permitted non-invasive assessment of structural data on cortical and trabecular bone.
  
  
  METHODS
  We investigated age-related changes in pQCT and finite element (FE) modelling parameters at the distal radius and distal tibia in a population-based cross-sectional study of 58 males and 74 females aged 20-79 years. Linear regression models including quadratic terms for age were used for inference.
  
  
  RESULTS
  Age-related changes and sex differences were generally similar for pQCT parameters at the radius and tibia. At each site, mean values for bone density, cortical thickness and trabecular micro-architecture (number, separation and thickness) were lower (trabecular separation higher) in women than men. Changes with age were most apparent for bone density and cortical thickness, which declined with age, in contrast to trabecular micro-architecture parameters which were not significantly associated with age (p > 0.05) in either sex. Cortical bone density and thickness declined faster in women than men after age 50 and trabecular bone density was consistently lower in women. FE-analysis predicted failure load decreased with age and percentage of load carried by trabecular bone increased (p < 0.05).
  
  
  CONCLUSIONS
  These data show contrasts in the effects of sex on the micro-architecture and strength of upper and lower limb bones with ageing. The faster decline in cortical bone thickness and density in women than men after age 50 and consistently lower trabecular bone density in women have implications for the excess risks of wrist and hip fractures in women.
authors.affiliation: Department of Public Health and Primary Care, University of Cambridge, Strangeways Research Laboratory, Wort's Causeway, Cambridge, CB1 8RN, UK.
authors.forename: N
authors.initials: N
authors.lastname: Dalzell
authors.forename: S
authors.initials: S
authors.lastname: Kaptoge
authors.forename: N
authors.initials: N
authors.lastname: Morris
authors.forename: A
authors.initials: A
authors.lastname: Berthier
authors.forename: B
authors.initials: B
authors.lastname: Koller
authors.forename: L
authors.initials: L
authors.lastname: Braak
authors.forename: B
authors.initials: B
authors.lastname: van Rietbergen
authors.forename: J
authors.initials: J
authors.lastname: Reeve
mesh_terms: D015502:Absorptiometry, Photon / Q000379:methods; D000328:Adult; D000368:Aged; D000375:Aging / Q000473:pathology / Q000502:physiology*; D004812:Epidemiologic Methods; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011884:Radius / Q000033:anatomy & histology / Q000000981:diagnostic imaging / Q000502:physiology*; D012016:Reference Values; D012727:Sex Characteristics; D013977:Tibia / Q000033:anatomy & histology / Q000000981:diagnostic imaging / Q000502:physiology*; D014057:Tomography, X-Ray Computed / Q000379:methods; D055815:Young Adult