Modélisation par éléments finis des plaques de croissance dans un modèle volumique du rachis

The longitudinal growth of long bones and vertebrae occurs in the cartilaginous growth plates. Growth plates are composed of three zones: the reserve, proliferative and hypertrophic zones. Each zone has its own compositional, structural, morphological and mechanical characteristics. Growth plates are sensitive to their mechanical environment, referred to as the mechanical modulation of growth. This phenomenon has key implications in infant and juvenile pathological progressive musculoskeletal deformities, such as idiopathic scoliosis, tibia vara and genus varus. The mechanical behavior of the growth plate is not completely characterized, due to the important heterogeneity among its three zones. Furthermore, very few modeling allow the possibility to study deformation mechanisms and stress states through the growth plate. The purpose of the present project was then to develop a numerical model to study the mechanical behavior of the growth plate in a geometrically personalized pediatric lumbar spine and to validate the developed modeling approach.

The first objective of the project was to develop a detailed finite element model of the pediatric spine personalized to the patient's geometry, including detailed modeling of the lumbar vertebrae, connective tissues and growth plates.

The second objective was to geometrically and mechanically validate the biomechanical model of the spine.

The third objective of the project was to determine the geometrical and mechanical characteristics of the growth plate that significantly affect its mechanical behavior.

The work carried out within the framework of this project demonstrated the relevance of the biomechanical model to investigate deformation mechanisms and stress states throughout the growth plate. The developed modeling approach is an innovating tool allowing the generation of a personalized detailed finite element model of the pediatric spine, and offers an alternative to experiments involving pediatric tissues of the lumbar spine. In its actual form, the model can be used to study the mechanical behavior of bones, connectives tissues and growth plates under quasi-static loading. Future studies should investigate the non-linearity of the material properties of the growth plate and improve the modeling articular facets. In the long term, this work could lead to the improvement of actual orthopedic treatments and to the development of new approaches using the mechanical growth modulation. (Abstract shortened by UMI.)