Endostructural and periosteal growth of the human humerus

Abstract

The growth and development of long bones are of considerable interests in the fields of comparative anatomy and palaeoanthropology, as evolutionary changes and adaptations to specific physical activity patterns are expected to be revealed during bone ontogeny. Traditionally, the cross‐sectional geometry of long bones has been examined at discrete locations usually placed at set intervals or fixed percentage distances along the midline axis of the bone shaft. More recently, the technique of morphometric mapping has enabled the continuous analysis of shape variation along the shaft. Here we extend this technique to the full sequence of late fetal and postnatal development of the humeral shaft in a modern human population sample, with the aim of establishing the shape changes during growth and their relationship with the development of the arm musculature and activity patterns. A sample of modern human humeri from individuals of age ranging from 24 weeks in utero to 18 years was imaged using microtomography at multiple resolutions and custom Matlab scripts. Standard biomechanical properties, cortical thickness, surface curvature, and pseudo‐landmarks were extracted along radial vectors spaced at intervals of 1° at each 0.5% longitudinal increment measured along the shaft axis. Heat maps were also generated for cortical thickness and surface curvature. The results demonstrate that a whole bone approach to analysis of cross‐sectional geometry is more desirable where possible, as there is a continuous pattern of variation along the shaft. It is also possible to discriminate very young individuals and adolescents from other groups by relative cortical thickness, and also by periosteal surface curvature.

Technical note: Capturing shape—Linear measurements and geometric morphometrics of the immature femora

“…Difficulties with morphological studies on juvenile long bones prior to the development of anatomical landmarks have been a topic of more recent investigation. To remedy such issues of unidentifiable landmarks, O'Mahoney et al (2023) has integrated cross‐sectional and GMM, through morphological mapping, to immature humeri to examine standard biomechanical properties such as cortical thickness, surface curvature, and pseudolandmarks across the diaphysis. The findings demonstrated the variability of cortical thickness and morphology along the shaft during childhood.…”