Development and validation of a discretised multi-body spine model in LifeMOD for biodynamic behaviour simulation

This paper presents a discretised musculoskeletal multi-body spine model using the LifeMOD Biomechanics Modeller. This was obtained by refining spine segments in cervical, thoracic and lumbar regions into individual vertebra segments, using rotational joints representing the intervertebral discs, building various ligaments between vertebrae and implementing necessary lumbar muscles. To validate the model, two comparison studies were made with in vivo intradiscal pressure measurements of the L4-L5 disc as well as extension moments, axial force and shear force around L5-S1 obtained from spine models available in the literature. The results indicated that the present model is in good correlation with both cases and matches well with experimental data which found that the axial forces are in the range of 3929-4688 N and shear forces up to 650 N. This study provides a preliminary overview of our ongoing work towards building bio-fidelity discretised multi-body spine models for investigating various medical applications. These models can be useful for incorporation into design tools for wheelchairs or other seating systems which may require attention to ergonomics as well as assessing biomechanical behaviour between natural spines and spinal arthroplasty or spinal arthrodesis. Furthermore, these models can be combined with haptic-integrated graphic environments to help surgeons to examine kinematic behaviours of scoliotic spines and to propose possible surgical plans before spine correction operations.