Year: 2014
Type: dissertation
Study design: Observational Study
Abstract: Aims: \n1) To determine the incidence or rates of fractures, the common sites of fractures, the \ncauses of fractures and grades of trauma causing fractures in urban South African \nchildren of different ethnic groups from birth until 17/18 years of age. \n2) To investigate the association between fracture prevalence, bone mass and physical \nactivity in South African children. \n3) To assess associations of fracture prevalence and bone mass in adolescents with \nmaternal fracture history and bone mass and sibling fracture history. \nDesign: \nUsing the Birth to Twenty longitudinal cohort of children, we obtained retrospective \ninformation on fractures and their sites from birth to 14.9 years of age on 2031 participants. \nThe ethnic breakdown of the children was black (B) 78%, white (W) 9%, mixed ancestry \n(MA) 10.5% and Indian (I) 1.5%. \nUsing the Bone Health cohort of the Birth to Twenty longitudinal study, we retrospectively \nobtained information of lifetime fractures until age 14.9 years in 533 subjects. Bone mass \n(measured by DXA), anthropometric data, physical activity scores and skeletal maturity were \nobtained at age 10 and 15 years. Comparisons were made between those who did and did not \nfracture within the same sex and ethnic groups. \nThe third component of the thesis utilized data from 1389 adolescent-biological mother pairs \nof the Birth to Twenty (Bt20) longitudinal study. Questionnaires were completed on \nadolescent fractures until 17/18 years of age and on sibling fractures. Biological mothers \ncompleted questionnaires on their own fractures prior to the age of 18 years. Anthropometric \nand bone mass data on adolescent-biological mother pairs were collected. \nResults: \nTwenty two percent of children had sustained a fracture one or more times during the first 15 \nyears of life (males 27.5% and females 16.3%; p<0.001). The percentage of children \nfracturing differed between the ethnic groups (W 41.5%, B 19%, MA 21%, I 30%; p<0.001). \nOf the children reporting fractures, 20% sustained multiple fractures. The most common site \nof fracture was the upper limb (57%). \nIn the second component of the thesis, white males who fractured were found to be \nsignificantly taller (10 years p < 0.05), more physically active (15 years p < 0.01) and had \nhigher lean body mass (10 years p=0.001; 15 years p<0.05) than those who did not fracture; \nwhile white females, who fractured, were fatter (10 and 15 years p< 0.05), than their nonfracturing \npeers. White males who fractured had greater BA (bone area) and BMC (bone \nmineral content) at most sites at 10 and 15 years; BA and BMC were no different between \nfracturing and non-fracturing children in the other ethnic groups. No anthropometric or bone \nmass differences were found between black children with or without fractures. \nThe third component of the thesis showed that an adolescent’s risk of lifetime fracture \ndecreased with increasing maternal lumbar spine (LS) BMC (24% reduction in fracture risk \nfor every unit increase in maternal LS BMC Z-score) and increased if they were white, male \nor had a sibling with a history of fracture. Adolescent height, weight, male gender, maternal \nBA and BMC, and white ethnicity were positive predictors of adolescent bone mass. White \nadolescents and their mothers had a higher fracture prevalence (adolescents: 42%, mothers: \n31%) compared to the black (adolescents: 20%, mothers: 6%) and mixed ancestry \n(adolescents: 20%, mothers: 16%) groups. \nConclusion: \nMore than twice as many South African white children fracture compared to black and mixed \nancestry children. This is the first study to show ethnic differences in fracture rates among \nchildren; a pattern that is similar to that found in South African postmenopausal women. The \nfactor associated with fractures in white boys appears to be participation in sports activities, \nwhile in white girls obesity appears to play a role. We were unable to find any factors that \ncould explain fractures in black children. Unlike the findings of some other studies, fractures \nin these children were not associated with lower bone mass or reduced skeletal size. \nMaternal bone mass also appears to play a role in determining fracture incidence in children, \nas the mother’s bone mass has a significant inverse association with their off-springs’ fracture \nrisk throughout childhood and adolescence. Furthermore, there is a strong familial component \nin fracture risk among South African adolescents and their siblings, as evidenced by the \nincreased risk of fracture in siblings of index children who have fractured during childhood \nand adolescence. \nDifferences in fracture rates and bone mass between families and individuals of different \nethnic origins may be due to differing lifestyles and/or genetic backgrounds.
Author: Kebashni Thandrayen
Language: English
Subfield: Orthopedics and Sports Medicine
Field: Medicine
Domain: Health Sciences
Open Access status: green
OpenAlex ID: W2239215833