The skeleton of a baby is weak but bone quality and strength increase during childhood with skeletal growth in the mid-thigh bones

Whether a bone will fracture or not, is primarily contingent on the quality of the bone. In turn bone quality largely depends on the organization and architecture of the bone, and its composition. While it’s known that aging and certain diseases such as osteoporosis alter bone quality and lead to a higher number of fractures, studies have shown that children and adolescents are more prone to fractures as well: around 30 % of children have at least one bone fracture, most of them stemming from minor accidents (so called low-energy trauma) and involving the growth plates (a specific area near the end of the bones from where the bone grows in length during childhood). However, to date it is still largely unknown how bone quality and mechanical competence progress in the growing skeleton during childhood.

Recently, in a paper published in the Journal of Bone Mineral Research, the ECTS Academy member Björn Busse and colleagues filled this scientific gap by performing a study in which they examined bone fragments harvested from the mid-thighbones (femur diaphysis) from children of different ages (ranging from 22 weeks of gestation till 14 years of age). The authors used different high-precision scientific techniques in order to investigate the quality and the properties of these children’s bones. Interestingly, they found that the bones of unborn babies or children less than 2 years old (fetal/infantile bones, which are more built like a scaffold and are therefore called woven bone) have lower quality and can resist less mechanical load than the mid-thighbones of 2 to 14 year old children. The authors revealed that the reasons for this worse bone quality of fetal/infantile bones are found in their more porous structure, lower mineralization and in the less organized alignment of collagen fibers compared to the denser structure and higher mineralization found in the mid-thighbones of children aged 2 to 14 years old. These results found for woven bone are important as they might help explain the higher fracture risk in children. As older children possess apart from the denser mid-thigh bone zones also areas of woven bones, namely in the growth plates, it might be at these areas of inferior woven growth plate bone, where the bones of children are the weakest and thus most prone to fracture.

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