ESPE Abstracts

Background: We have previously shown that bone age (BA) assessment by SonicBone BAUS^TM, measuring the speed of sound (SOS) of US waves propagating along measured bone, is reproducible and comparable to both GP and TW3 x-ray assessment of BA. This provides a safe and irradiation-free method to the assessment of BA in healthy children.

Objective and hypothesis: We aimed to understand the dependency of BA on a child’s height and BMI using sonometeric bone age (SBA), and hypothesized positive correlations.

Method: SBA was analysed separately and averaged for the wrist (radius-ulna epiphyses), metacarpal epiphyses and the phalanx’ ossification centers in 317 healthy girls and 333 boys, age range 4–15/4–17 resp., and the difference from chronological age was regressed onto their height SDS and BMI SDS.

Results: A child’s height SDS is strongly and positively correlated with the SBA deviation from the chronological age in the wrist (r²=0.30, P<0.0001), metacarpals (r²=0.29, P<0.0001), phalanx (r²=0.47, P<0.0001), and the mean SBA (r²=0.40, P<0.0001). When 120 pre-pubertal girls age 4–8 and 147 boys age 4–9, are analysed separately, the correlation is reduced to r²=0.215, P=0.019 in girls but remains strong in boys, (r²=0.304, P<0.0001). A child’s BMI SDS is also positively correlated with the SBA deviation from chronological age in the wrist (r²=0.25, p<0.0001), metacarpals (r²=0.17, p< 0.0001) phalanx (r²=0.13, P<0.001), and the mean SBA (r²=0.22, P<0.0001). In separate analysis of pre-pubertal children, the BMI correlations disappear.

Conclusions: i) Shorter and thinner pubertal but not pre-pubertal children have delayed BA as compared to taller and heavier children. ii) The full-length phalanx maturation is affected by height more than the wrist and metacarpals’ epiphyses. iii) The radius-ulna epiphyses are affected by BMI more than the metacarpals and phalanx. iv) These influences have now on to be accounted for in the assessment of a BA.

Conflict of interest: SO is employed by SonicBone, NKM and ZH are independent consultant.

Funding: The study was funded by SonicBone Ltd Rishon Lezion.