title: Evidence of altered matrix composition in iliac crest biopsies from patients with idiopathic juvenile osteoporosis.
abstract: OBJECTIVE
  Idiopathic juvenile osteoporosis (IJO) is a rare condition in children, characterized by bone pain and long bone and vertebral fractures. Previously, IJO bone was solely characterized by histomorphometry and quantitative computed tomography. The goal of this study is to describe IJO bone composition.
  
  
  METHODS
  Fourier transform infrared imaging (FTIRI), a vibrational spectroscopic technique providing spatially resolved images of chemical composition, was used to determine whether iliac crest biopsies from children with IJO differed in composition from and age- and sex-matched controls, and, as a secondary analysis, whether IJO bone showed the same disease dependent change in composition as do iliac crest bone biopsies from women with post-menopausal osteoporosis (PMO). Wilcoxon rank tests and linear regressions were used to analyze FTIRI variables (mineral-to-matrix ratio, carbonate-to-phosphate ratio, crystallinity, acid phosphate substitution, collagen maturity) and their individual pixel distributions (heterogeneity).
  
  
  RESULTS
  Mineral-to-matrix ratio was comparable in IJO and age-matched controls. Contrastingly, collagen maturity (also known as collagen cross-link ratio) was higher in cortical and cancellous IJO bone compared with juvenile controls. Acid phosphate substitution was greater in IJO cancellous bone than in age-matched controls, suggesting IJO bone mineral is formed more recently, reflecting a slower mineralization process. This agrees with findings of increased heterogeneity for mineral-to-matrix and collagen maturity ratios in IJO cancellous bone. There were negative correlations between cancellous collagen maturity and previously reported histomorphometric bone formation markers. There were no correlations with indices of remodeling.
  
  
  CONCLUSIONS
  IJO bone, similar to PMO bone, had elevated collagen maturity relative to its age-matched controls. This emphasizes the importance of the collagen matrix for bone health. IJO bone differed from PMO bone as IJO bone contains more recently formed mineral than age-matched controls but has a more mature matrix, whereas in PMO bone both mineral and matrix have older characteristics.
authors.affiliation: a Mineralized Tissue Laboratory , Hospital for Special Surgery , New York , NY , USA.
authors.forename: Ignacio
authors.initials: I
authors.lastname: Garcia
authors.affiliation: a Mineralized Tissue Laboratory , Hospital for Special Surgery , New York , NY , USA.
authors.forename: Vincent
authors.initials: V
authors.lastname: Chiodo
authors.affiliation: b Department of Epidemiology and Biostatistics , Milken Institute School of Public Health, The George Washington University , Washington , DC , USA.
authors.forename: Yan
authors.initials: Y
authors.lastname: Ma
authors.affiliation: a Mineralized Tissue Laboratory , Hospital for Special Surgery , New York , NY , USA.
authors.forename: Adele
authors.initials: A
authors.lastname: Boskey
mesh_terms: D001706:Biopsy; D015519:Bone Density; D002648:Child; D003094:Collagen / Q000378:metabolism*; D005109:Extracellular Matrix / Q000378:metabolism / Q000473:pathology; D005260:Female; D006801:Humans; D007085:Ilium / Q000378:metabolism / Q000473:pathology; D010024:Osteoporosis / Q000378:metabolism / Q000473:pathology; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D003094:Collagen
keywords: Collagen maturity; FTIRI; idiopathic juvenile osteoporosis; material properties; osteoporosis