The objective of this study is to adjust and enhance the existing lumbar spine model with more detailed passive elements to simulate the rotational moment/force produced by intervertebral disc, facet articulations and ligaments.

The model files included a modified lumbar model with passive elements and a full body model incorporating this lumbar model. The files also included setting files of external loads (10·Nm moment in three principal axes) for ROM validation.

The ligaments in L3-S1 were modeled by Ligament elements. The rotational stiffness produced by intervertebral disc or facet articulation was modeled using ExpressionBasedBushingForce element.

The model was created based on other previously developed OpenSim models (https://simtk.org/projects/fullbodylumbar, https://simtk.org/home/lumbarspine, https://simtk.org/projects/intervertebr_jr, https://simtk.org/projects/ulb_project).