We created a total of 26 children and adolescent full-body models (a male and female model for each year of age between 6 and 18 years), consisting of a detailed and fully articulated thoracolumbar spine and rib cage, a lumped head and neck body as well as upper and lower extremities.

Initial version (compatible with OpenSim 3.3):
Male and female versions of our previously developed and validated “thoracolumbar spine and rib cage model” (https://simtk.org/projects/spine_ribcage) were combined with the “Gait2354 model” (https://simtk-confluence.stanford.edu/display/OpenSim/Gait+2392+and+2354+Models) and adjusted for segmental length and mass distributions, center of mass positions and moments of inertia of the major body segments, sagittal pelvis and spinal alignment as well as trunk muscle cross-sectional areas (CSA) based on data obtained from the literature.
The models were validated by comparing predictions of maximal trunk muscle strength, lumbar disc compressibility, intradiscal pressure and trunk muscle activity to in vivo measurements reported in the literature (https://doi.org/10.1016/j.jbiomech.2019.07.049).

Latest version (compatible with OpenSim 4.x):
Male and female versions of the most recent release of the thoracolumbar spine and rib cage model (Fullbody_OS4.x_v2.0; https://simtk.org/projects/spine_ribcage) were adjusted for segmental length and mass distributions, center of mass positions and moments of inertia of the major body segments, sagittal pelvis and spinal alignment as well as trunk muscle cross-sectional areas (CSA) based on data obtained from the literature. In addition, the abdomen body was realigned, and the muscle tendon-to-fiber length ratios were adjusted to the new total muscle length resulting from the implementation of age-specific sagittal alignment.