ESPE Yearbook of Paediatric Endocrinology

To read the full abstract: Clinical Orthopaedics and Related Research. 476(11):2112–2122, 2018

The century-long Fels Longitudinal Study of human growth and development aimed to track when growth plate fusion started and completed in children born as far back as 1915. Among 1292 children, each with between 1 to 30 serial left hand-wrist radiographs, children born in the 1990s reached skeletal maturity faster and sooner than those born in the 1930s.

In the dialectics of physical anthropology and auxology, ‘bone age’ is erroneously understood to be an expression of the biological maturity of a child. Inferring from a ‘bone age’ film of the hand and wrist, the clinician may contemplate diagnostic possibilities and predict height potential. He may recommend types of physical activity, or the timing of orthodontic procedures and orthopedic surgery.

The ‘age’ in ‘bone age’ insinuates the concept of precision and unity, which it does not provide, and the assignment of ‘years’ as its units makes little sense. We now have data to suggest that bone maturation is subject to environmental circumstances. The study does not address what might be the cause of faster maturation but hints to exposure to environmental hormones and hormone mimickers. However, it is more likely that the change is due to the earlier and faster puberty that is widely reported in contemporary children. It is surprising that while sex steroids, mostly estrogen, are secreted today much earlier than in the 1930s and menarche occur earlier by as much as 2 years, bones mature faster by only 7 and 10 months in boys and girls, respectively.

These findings directly impact the timing of the clinical care of certain pediatric orthopedic conditions, such as correction of leg-length differences, scoliosis and the timing of growth hormone therapy.

The authors suggest that there is a “new normal” for timing when kids’ skeletons reach full maturity, but says nothing about developmental milestones before epiphyseal fusion. For the pediatric endocrinologist, who is used to individual variability in bone maturation, this is not much of a surprise and we doubt that it requires new norms (1).

Reference: 1. Hochberg Z. Diagnosis of endocrine disease. On the need for national-, racial-, or ethnic-specific standards for the assessment of bone maturation. Eur J Endocrinol. 2016 Feb;174(2):R65–70.