Abstract
Correlations of the length, width and cortical thickness and some indices calculated from these measurements between the second and the third metacarpals were examined, based on 1072 radiographs of 88 male and 91 female twins aged 12 to 18 years. Although most correlations tended to be significant, the magnitude of correlation is higher in the length, followed by the width, than in the cortical thickness. However, heritability is almost the same between the second and the third metacarpals in both sexes. Both metacarpals probably show the same usefulness as an indicator of compact bone mass, though the value is somewhat greater in the second than in the third. However, since both metacarpals do not always show signigicant correlations for the cortical thickness, it seems to be reasonable to use both bones, at least, to estimate an exact compact bone mass for an individual.
