title: Bone mineral density in developing children with osteogenesis imperfecta: a longitudinal study with 9 years of follow-up.
abstract: OBJECTIVE
  Osteogenesis imperfecta (OI) is a heritable disorder of connective tissue caused by a defect in collagen type I synthesis. For bone, this includes fragility, low bone mass, and progressive skeletal deformities, which can result in various degrees of short stature. The purpose of this study was to investigate development of bone mineral density in children with OI.
  
  
  METHODS
  Development of lumbar bone mineral density was studied retrospectively in a cohort of 74 children with OI. Mean age was 16.3 years (SD 4.3). In 52 children, repeated measurements were available. Mean age at the start of measurement was 8.8 years (SD 4.1), and mean follow-up was 9 years (SD 2.7). A longitudinal data analysis was performed. In the total cohort (74 children), a cross-sectional analysis was performed with the latest-measured BMD. Age at the latest BMD measurement was almost equal for girls and boys: 17.4 and 17.7 years respectively.
  
  
  RESULTS
  Mean annual increase in BMD in the 52 children was 0.038 g/cm(2)/year (SD 0.024). Annual increase in BMD was statistically significantly higher in girls, in both the unadjusted and adjusted analysis. In cross-sectional analysis, in the whole cohort the latest-measured lumbar BMD was significantly higher in girls, in the children with OI of type I, in walkers, and in those who were older, in both unadjusted and adjusted analysis.
  
  
  CONCLUSIONS
  During 9 years of follow-up, there appeared to be an increase in bone mineral density, which was most pronounced in girls. One possible explanation might be a later growth spurt and older age at peak bone mass in boys.
authors.affiliation: Department of Orthopaedic Surgery, Wilhelmina Children's Hospital, University Medical Center Utrecht, the Netherlands. diekekok@tele2.nl
authors.forename: Dieke H J
authors.initials: DH
authors.lastname: Kok
authors.forename: Ralph J B
authors.initials: RJ
authors.lastname: Sakkers
authors.forename: Hans E H
authors.initials: HE
authors.lastname: Pruijs
authors.forename: Pieter
authors.initials: P
authors.lastname: Joosse
authors.forename: René M
authors.initials: RM
authors.lastname: Castelein
mesh_terms: D000293:Adolescent; D015519:Bone Density / Q000502:physiology*; D002648:Child; D002657:Child Development / Q000502:physiology*; D003430:Cross-Sectional Studies; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D010013:Osteogenesis Imperfecta / Q000503:physiopathology*; D012189:Retrospective Studies; D055815:Young Adult