ONSETS, COMPLETIONS AND SPANS OF OSSIFICATION IN THE 29 BONE-GROWTH CENTERS OF THE HAND AND WRIST

The film series of the right hands of 133 Boston children have been studied independently to obtain age equivalents for onset of ossification and completion of ossification in 29 bone-growth centers of the hand. Each of the intervals between onset and completion, namely, span of the osseous stage, has been calculated, and the means and standard deviations of each of the three variables are summarized. The results show age equivalents and age-orders closely resembling the data in two preceding studies, where the assessment procedure was the same as that used in this study. An onset profile and a completion profile have been drawn from these mean and standard deviation values for each sex. The data reported in this paper for the 29 centers of the hand and previously for 21 centers from five regions of the body, show the following: 1) The time-order of onset differs significantly from the time-order of completion. 2) The time-order onset profile reveals a characteristic clustering of onsets. 3) The correlations between onset and completion ages for the 133 children do not show that the time of completion can be routinely forecast by onset ages. However, the later the onset the better the prediction of completion time. 4) A developmental range graph constructed from assessments of skeletal age of the 29 centers of the hand reflects the schedules of onsets and completions for individual children. However, the "lifetime" of each of the onsets and completions is very brief and corresponds closely with the skeletal age curve during the first 4 years and during adolescence.