Developing a 3D multi-body simulation tool to study dynamic behaviour of human scoliosis

Abstract

Knowledge of the movements of whole spine is important for evaluating clinical pathologic conditions that may potentially produce unstable situations in human body movements. At present these are few studies that report systematic three-dimensional (3D) movement analysis of the whole spine. Scoliosis is one of the asymmetric conditions in the spine. Scoliosis is a complicated condition characterized by a lateral curvature of the spine and accompanied by rotation of the vertebrae about its axis. The objective of this study is to simulate a 3D multi-body model of the human body, especially body with spine deformity (scoliosis) for investigating various medical applications. This personalized multi-body scoliotic spine model is developed based on patient anthropometric data. Such a model is able to capture the dynamic interactions between vertebrae, muscles, ligaments, and external boundary conditions. In this study, the scoliotic spine of three patients was modeled using 2D X-ray images to investigate the biomechanics of abnormal spines which were examined in upright posture. The spine joint forces and torques were found in this posture for all models and the results were discussed. Furthermore, the biomechanics of human scoliotic and normal spine in daily maneuvers such as flexion, bending and twisting exercises were investigated with conducting musculoskeletal model with motion capture data of the subjects. The range of motion (ROM) of the patient was compared with the ROM of the healthy subject with similar anthropometric data in all exercises. The force and torque in lumbar joints from scoliosis simulated model in these exercises were compared to those of the normal one. Finally, this simulation model was used to study the effect of corrective spine surgery (instrumentation) on the spinal forces and range of motion. This model can be used as a tool for wheelchair design or other seating systems design which may require attention to ergonomics as well as assessing biomechanical behaviour between normal and scoliotic spines.