Abstract
Assessment criterion of the brachymesophalangia 5 (hereafter abbreviated Bmp 5) was studied using radiographs of both hands of 141 male and 128 female adult Japanese.
Lengths of 2nd to 5th middle phalanges (MP2L-5L), distal and proximal phalanges (DP5L, PP5L), and breadths of 4th and 5th middle phalanges (MP4B and 5B) were measured (Fig. 2). Groups of apparently normal and Bmp 5 were selected and their means and mean differences of phalangeal measurements were calculated (Tab. 2). Apparent Bmp 5 sample had 5th middle phalanges shorter and broader than those of the normal sample, differences being significant at 0.01 level.
Coefficients of correlation between 5th and 4th middle phalanges were the largest and those between 5th middle and distal phalanges were the smallest of all coefficients between the lengths of the 5th middle phalanx and other phalanges in both sexes (Tab. 3 and 4).
Discriminant functions based on 6 measurements (MP2L-5L, MP 4B and 5B) for the above two groups were calculated for each sex (Tab. 6). Incidences of the Bmp 5 assigned by these discriminant functions were 3.2% in male and 13.7% in female (Fig. 3).
In order to find simpler criterions for the Bmp 5, various indices were examined for their frequency distributions between these assigned normal and Bmp 5 groups (Fig. 4) and for their mutual correlations (Tab. 8 and 9). As a result, the best index-criterions of Bmp 5 were found to be MP5L/MP4L<0.55 and MP5B/MP5L>0.60 in male, but in female, though the assignment by discriminant function seemed to be possible, no simple index was found effective probably because of higher occurrence of transitional forms between normal and Bmp 5 hands than in the male.
