Assessment of a parametric thoracic spine model for the generation of in silico cohorts

In silico digital twins of spine segments are a valuable technology with the potential to generate biomechanically relevant information, not always obtainable with expensive in vitro measurements and invasive in vivo techniques. The present study introduces a novel strategy to generate a parametric CAD model of the thoraco-lumbar spine representative of the healthy adult population in standing posture. The CAD model requires few independent input parameters (VBHP, TK, LL, SS) to be completely defined. Regression equations obtained by fitting anatomical literature data were generate and implemented. The model was furtherly refined with the addition of the rib cage, modelled on the base of mean anatomical data inserted as inputs. To demonstrate the capability of the CAD model to be used for relevant biomechanical analyses, a representative thoracic functional spinal unit T6-T7-R7 functional unit was isolated and the material properties of each sub-structure (annulus fibrosus, nucleus pulposus, neural arch, facet joints, ligaments, ribs and sternum) were calibrated following a step-by-step backward stepwise reduction procedure.