An X-ray diffraction investigation of age-related changes in the crystal structure of bone apatite

Evidence relating to the existence of crystalline bone mineral in vivo is considered, and bone apatite crystal structure investigated using an x-ray powder diffraction technique. Specimens of femoral compacta excised post-mortem from male and female subjects ranging from 3 1/2 years to 87 years of age have been studied. Values of the ratio c/a of bone apatite crystal cell axes for females are significantly higher (p less than 0.05) than for males. Moreover, significant change of c/a with age is observed for males (p = 0.0005) but not for females (p = 0.30). Differences in c/a are interpreted as indicating substitution of constituent ions in the bone apatite crystals.