Bilateral asymmetry of cross-sectional radiogrametric and microdensitometric measurements in the second metacarpal.

On the basis of radiographs of the midshaft cross-section of the second metacarpal in 102 male and 96 female Japanese, aged 30-98 years, side-related differences of radiogrametric, biomechanical and microdensitometric parameters are examined. The bone section is more or less elliptical, and the major axis tilts somewhat radially from the median line at its dorsal end. Significant correlations are found between the right and left hands for each parameter at p less than or equal to 0.01. Bone size (BW and BA) and the relative magnitude of bending rigidity of a section (Imax and Imin) are significantly or arithmetically greater in the right hand than in the left. However, the cortical mass relative to the bone (MCI and CA/BA), biomechanical shape index (Imax/Imin and BWmax/BWmin) and total, mean and true bone density (TPA, MBD and MPH) are nearly identical in both hands. The cortical thickness and total mean bone density is significantly greater in the dorsovolar direction than in the radioulnar, and on the ulnar side than on the radial and on the volar side than on the dorsal, but the true bone density does not show such differences.