Computer-aided skeletal age scores in healthy children, girls with Turner syndrome, and in children with constitutionally tall stature.

The manual Tanner-Whitehouse 2 method has recently been transformed into a computer-aided skeletal age scoring system (CASAS), which rates either the complete TW-RUS score (13b model) or a subset consisting of radius, ulna, and the four bones of the third finger (6b model). In this study the reliability of CASAS was evaluated in healthy children, and the 13b model was compared with the manual ratings and with the 6b model in (subgroups of) 151 healthy children, 87 girls with Turner syndrome, and 362 children with constitutionally tall stature. In addition, reference curves for bone maturation in Turner syndrome and constitutionally tall stature are presented. Some of mean differences in methods were statistically significant; however, because these mean differences were less than 0.4 bone age "year," they are clinically not significant. In all comparisons the range of the difference between the methods (either with the 6b or the 13b model) was considerable, but the combined within- and between-components of variance (0.7%) were in the same order of magnitude as reported for the manual readings. In general, the percentage of equal stage ratings on duplicate assessments was high (+/- 90%). Our data indicate that this computerized method is applicable in these groups of children. The use of the 6b model seems preferable because it is less time-consuming than the rating of 13 bones. In view of the percentages of manual insertions of a stage (up to 8% in all groups) the clinical use of this CASAS version (3.5) seems to be more efficient, particularly with longitudinal studies. Manual substitution of a stage should be avoided, and when performed its percentage and the limits for the acceptance of disagreement should be reported.