Standard deviation score charts of skeletal maturity and its velocity in Swedish children assessed by the Tanner-Whitehouse method (TW2-20).

Reference values, means and standard deviations for skeletal maturity of Swedish children, evaluated in terms of the Tanner-Whitehouse method (TW2-20), have been expressed in mathematical functions. Almost 4000 radiograms have been assessed. The radiograms were taken on 212 children aged between one month and 18 years as part of a longitudinal study of growth and development. Up to the age of 10 years, the Swedish children had a more advanced skeletal maturation (about 0.5 SD) than the British children. Means and standard deviations have been used in preference to medians and centiles, since this makes it possible to use the results in the assessment of children with grossly deviating maturation. The selected functions were chosen in order to give a good description of the empirical distributions and no biological implications of the estimated parameters were sought. This method improves the assessment of skeletal maturity in several respects; reference values are given parametrically, which facilitates the computing of the individual standard deviation scores, and reference charts are presented for both attained scores and velocity scores (for boys between one and 13 years and for girls between one and 11 years).