Altered bone composition in children with vertebral fracture.

Primary osteoporosis in children often leads to vertebral fractures, but it remains unknown whether these fractures associate with changes in bone composition. This study aimed to determine the differences in bone composition in fracture-prone children with and without vertebral fractures, as assessed by Fourier transform infrared spectroscopic imaging (FTIRI) and bone histomorphometry. Iliac crest bone biopsies (n = 24) were obtained from children who were suspected of primary osteoporosis based on evidence from the fracture history and/or low bone mineral density (BMD) by dual-energy X-ray absorptiometry. Vertebral morphology was determined by radiography. Bone biopsies were analyzed using histomorphometry and FTIRI. Phosphate-to-amide I, carbonate-to-phosphate, carbonate-to-amide I, and cross-link ratio (collagen maturity) were calculated. Children with (n = 14) and without (n = 10) vertebral fracture were compared. Low cancellous bone volume (BV/TV) was detected by histomorphometry in 36% of the children with vertebral fracture, and bone turnover rate was abnormal in 64% of them. Children with vertebral fractures had lower carbonate-to-phosphate ratios (p < .05) and higher collagen maturity (p < .05) than children without vertebral fracture. The children with low BV/TV in biopsy showed lower carbonate-to-amide I ratios (p < .05) than the children with normal bone volume. This study showed changes in bone composition among fracture-prone children who had sustained a vertebral fracture. The observed changes in bone composition in these children may contribute to their greater propensity to sustain vertebral fractures.