title: Effect of ethnicity and sex on the growth of the axial and appendicular skeleton of children living in a developing country.
abstract: Bones in the axial and appendicular skeletons exhibit heterogeneous growth patterns between different ethnic and sex groups. However, the influence of this differential growth on the expression of bone mineral content is not yet established. The aims of the present study were to investigate: 1) whether there are ethnic and sex differences in axial and appendicular dimensions of South African children; and 2) whether regional segment length is a better predictor of bone mass than stature. Anthropometric measurements of stature, weight, sitting height, and limb lengths were taken on 368 black and white, male and female 9-year-old children. DXA (dual-energy x-ray absorptiometry) scans of the distal ulna, distal radius, and hip and lumbar spine were also obtained. Analyses of covariance were performed to assess differences in limb lengths, adjusted for differences in stature. Multiple regression analyses were used to assess significant predictors of site-specific bone mass. Stature-adjusted means of limb lengths show that black boys have longer legs and humeri but shorter trunks than white boys. In addition, black children have longer forearms than white children, and girls have longer thighs than boys. The regression analysis demonstrated that site-specific bone mass was more strongly associated with regional segment length than stature, but this had little effect on the overall pattern of ethnic and sex differences. In conclusion, there is a differential effect of ethnicity and sex on the growth of the axial and appendicular skeletons, and regional segment length is a better predictor of site-specific bone mass than stature.
authors.affiliation: Medical Research Council Mineral Metabolism Research Unit, Department of Pediatrics and Child Health, Chris Hani Baragwanath Hospital, University of the Witwatersrand, Johannesburg, South Africa. nyatilh@medicine.wits.ac.za
authors.forename: Lukhanyo H
authors.initials: LH
authors.lastname: Nyati
authors.forename: Shane A
authors.initials: SA
authors.lastname: Norris
authors.forename: Noel
authors.initials: N
authors.lastname: Cameron
authors.forename: John M
authors.initials: JM
authors.lastname: Pettifor
mesh_terms: D000886:Anthropometry / Q000379:methods; D044383:Black People / Q000706:statistics & numerical data*; D049628:Body Size; D015519:Bone Density / Q000502:physiology; D001846:Bone Development / Q000502:physiology*; D002648:Child; D003430:Cross-Sectional Studies; D003906:Developing Countries / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D012044:Regression Analysis; D012727:Sex Characteristics; D013019:South Africa / Q000453:epidemiology; D044465:White People / Q000706:statistics & numerical data*