Humeral Development Throughout the Arc of Childhood-A 3D MRI Study.

A quantitative understanding of humeral morphology through the arc of pediatric development is crucial in optimizing the treatment of pediatric shoulder-related orthopedic disorders and athletic overuse injuries. However, data regarding modern normative humeral development are not available. Thus, the aim of this study is to derive biomechanically relevant humeral size and shape measures from a pediatric cohort spanning infancy to adulthood (age 0.6-18.8 years, n = 52). Three-dimensional models were generated by segmenting axial MR images from typically developing, dominant-side humeri. Quadratic regression defined the relationship between each parameter and age. In a sub-cohort, we compared humeral morphological parameters between dominant and nondominant humeri from the same child. Children exhibited a pattern of steady growth, anteversion, and declination throughout development that gradually tapered off toward adulthood. Size measurements had the strongest regressions with age (head diameter: R² = 0.908; humeral length: R² = 0.960; epicondylar width: R² = 0.889, p < 0.001). Version was more variable and less strongly related to age (R² = 0.238, p < 0.001), whereas inclination demonstrated the weakest relationship with age (R² = 0.128, p < 0.05). The shallow curve fits indicated that there is not a single age where adult values were attained. In the sub-cohort analysis, the data from the right and left limbs were no different and correlated, supporting the use of the contralateral limb as a comparator when unilateral pathology is present, if the contralateral parameters fall within the normative range. Our data set provides a unique asset for pediatric clinical interventional planning as it provides the only current in vivo humeral development measures throughout the arc of childhood.