Sensitivity of GHBMC Lumbar Spine Biomechanical Response to Subject-specific Geometric Morphing and Soft Tissue Material Property Scaling

Paper in proceeding, 2024

Morphing techniques allow for the incorporation of diverse anthropometries in human body models. In addition, material properties can be adjusted to incorporate the effects of aging. Our objective was to evaluate the effect of subject-specific (SS) geometric morphing and material property scaling on prediction of component lumbar spine biomechanical response in compression-flexion loading. The mesh of the GHBMC-M50 lumbar spine was morphed to SS geometries using CT scans representing pre-test initial positions. Eight specimens were selected, which represented geometry close to and substantially different from the baseline and both males and females. Secondly, soft tissue material properties of the ligaments and intervertebral discs were scaled to determine the effects of increasing or decreasing stiffness. Flexion moment-angle responses were relatively insensitive to changes in geometry and individual changes in soft tissue properties. However, the combined effect of scaling all soft tissues was greater than both individual scaling and morphing. All models captured the experimental response at low sagittal angles, but all models deviated from experiments at higher angles and moments. Given the assessed version of the GHBMC and the applied loading conditions, the effort of incorporating added complexity within the lumbar spine did not substantially alter the measured model outcomes.