Developmental implications of dichotomous ossification sequences in the wrist region.

ABSTRACT As shown in radiographs of 3,764 children of European ancestry under 11 years of age, there are 55 dichotomous (present-absent/absent-present) ossification sequences for nine wrist region centers i n boys and 48 such sequences for girls, with statistically significant sexual dimorphism in more than half of the “alternative” sequences. Substantial samples of Meso-American origin (“Chicanos”) and largely-African origin (“Blacks”) evidence additional dichotomous ossification sequences, with clear population differences, while Down’s syndrome children (47 ,G f ) show a major excess of the numerically rarer sequences of the wrist region.