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Using FEM to Investigate the Cervical Spine Injury with Optimized Neck Muscle Forces during Collisions
Poster 249, Poster Session 2/Rehabilitation. 14:10-15:10, Room 103 & Alley Area
S724
Using FEM to Investigate the Cervical Spine Injury with Optimized Neck Muscle Forces during Collisions 1
Y.Y. Fan, B.S.1 and S.W. Yang, PH.D1 Institute of Biomedical Engineering, National Yang Ming University, Taipei, Taiwan, Corresponding author: [email protected] Website: http://rehab.ym.edu.tw
INTRODUCTION Motorcycles are one of the major conveyances in Taiwan, and the motorcycle accidents can cause severe neck injury; the motorcyclists may suffer from spinal cord injury (SCI) and possibly be incapable of activities of daily living (ADL). Due to the limitation of animal, cadaver, and volunteer in experiments simulating neck injury, the computational modeling approach is chosen to investigate the neck injury mechanism. One study investigates the impact force value and collision part of the motorcyclist during the collision of the motorcycle and the car using computational approach by ADAMS, including head-on collision (35 km/hr against 55 km/hr), side collision (34 km/hr and 35 km/hr), side-swipe collision (35 km/hr and 54.7 km/hr), and rear-end collision (22 km/hr and 62 km/hr)[1]. The other study [2] indicates the contribution of muscles forces and moment generating capacities of neck influences the injury mechanism and the simulation results of the neck, including the fracture locations and the proposed failure criterions. The purpose of this study is combining optimization for determination of muscle force activation patterns and finite element analysis of the head-neck-torso complex, so as to investigate neck injury mechanism with muscle force contributions under collisions.
the model of the head-neck-torso complex and the activation pattern of the muscles are determined, the LS-DYNA is used to investigate the failure region by the stress distribution and the neck injury mechanism with different patterns of muscle activation during collisions; the non-activated state of the muscles, the relax state of the muscles, the tensed state of the muscles, and the fully activated state of the muscles. RESULTS AND DISCUSSION The preliminary result: after adjusting the relative position of the head-neck model and the torso model, and constraining the complex of head-neck-torso, five groups of the muscles are currently connected to the model. The origin and insertion of the muscles are referred to the published data and adjusted according to the anatomy. However, the validation of the constructed head-neck-torso model is still proceeding. The procedure that follows the validation is, first, the attachments of neck muscles with optimized forces; second, investigation of cervical spine injury with neck muscle forces by FEM; finally, to compare the threshold of injury and injury location of the cervical spine.
Keyword: impact, cervical spine, muscle, finite element, optimization. METHODS The kinematics data of motorcycle-car collisions from ADAMS simulation [1] is used as constraints for optimization and boundary conditions for finite element model of head-neck-torso complex. In order to complement the model of head-neck-torso complex; the head-neck model is connected to the torso part of HYBRID-III model. After the head-neck part is connected to the torso part, the connected model is validated with the dynamical responses of the head-neck complex during axial impact loading [3]; additionally, the muscles are attached to the head-neck-torso model according to the published origin and insertion data, and muscles attached include hyoid, semispinalis capitis, splenius capitis, sternocleidomastoid, and trapezius presently [4].The equations of equilibrium, constraints, gravity, and the object function are derived according to the four collisions in ADAMS simulation (7586N at 0.22s, 15874N at 0.85s; 6976N at 0.26s; 213N at 0.6 s, 650N at 1.4 s; 9391N at 2.1s). The object function is determined, assuming that only two states of neck muscle activation dominate the behavior during collisions between motorcycle and car. One is the relaxed state, and thus the object function can be minimizing the fatigue; the other is tensed state, and thus the object can be maximizing the endurance. Once these are determined, the LS-OPT is used to optimize the initial conditions of the muscle activation of each muscle [5]. Both Journal of Biomechanics 40(S2)
Figure 1: The head-neck-torso model with muscles, which include hyoid, semispinalis capitis, splenius capitis, stermocleidomastoid, and trapezius muscles. REFERENCES 1. Wu CY, Master Thesis, Institute of Biomedical Eng., National Yang Ming University, Taiwan, 2003. 2. Lee IH, et al., IJAT, Vol. 5, No. 1, pp. 33-46, 2004. 3. Nightingale, et al, J Biomech, Vol. 29, No. 3, pp. 307-318, 1996 4. Oi Nelson, et al, Stapp Car Crash Journal, Vol. 48, pp. 397-417, 2004 5. Chancey VC, et al, Stapp Car Crash Journal, Vol. 47, pp. 135-153, 2003 ACKNOWLEDGEMENTS This study is supported by National Science Council of R.O.C Grant- NSC94-2213-E010-007
XXI ISB Congress, Poster Sessions, Thursday 5 July 2007
S724
Using FEM to Investigate the Cervical Spine Injury with Optimized Neck Muscle Forces during Collisions 1
Y.Y. Fan, B.S.1 and S.W. Yang, PH.D1 Institute of Biomedical Engineering, National Yang Ming University, Taipei, Taiwan, Corresponding author: [email protected] Website: http://rehab.ym.edu.tw
INTRODUCTION Motorcycles are one of the major conveyances in Taiwan, and the motorcycle accidents can cause severe neck injury; the motorcyclists may suffer from spinal cord injury (SCI) and possibly be incapable of activities of daily living (ADL). Due to the limitation of animal, cadaver, and volunteer in experiments simulating neck injury, the computational modeling approach is chosen to investigate the neck injury mechanism. One study investigates the impact force value and collision part of the motorcyclist during the collision of the motorcycle and the car using computational approach by ADAMS, including head-on collision (35 km/hr against 55 km/hr), side collision (34 km/hr and 35 km/hr), side-swipe collision (35 km/hr and 54.7 km/hr), and rear-end collision (22 km/hr and 62 km/hr)[1]. The other study [2] indicates the contribution of muscles forces and moment generating capacities of neck influences the injury mechanism and the simulation results of the neck, including the fracture locations and the proposed failure criterions. The purpose of this study is combining optimization for determination of muscle force activation patterns and finite element analysis of the head-neck-torso complex, so as to investigate neck injury mechanism with muscle force contributions under collisions.
the model of the head-neck-torso complex and the activation pattern of the muscles are determined, the LS-DYNA is used to investigate the failure region by the stress distribution and the neck injury mechanism with different patterns of muscle activation during collisions; the non-activated state of the muscles, the relax state of the muscles, the tensed state of the muscles, and the fully activated state of the muscles. RESULTS AND DISCUSSION The preliminary result: after adjusting the relative position of the head-neck model and the torso model, and constraining the complex of head-neck-torso, five groups of the muscles are currently connected to the model. The origin and insertion of the muscles are referred to the published data and adjusted according to the anatomy. However, the validation of the constructed head-neck-torso model is still proceeding. The procedure that follows the validation is, first, the attachments of neck muscles with optimized forces; second, investigation of cervical spine injury with neck muscle forces by FEM; finally, to compare the threshold of injury and injury location of the cervical spine.
Keyword: impact, cervical spine, muscle, finite element, optimization. METHODS The kinematics data of motorcycle-car collisions from ADAMS simulation [1] is used as constraints for optimization and boundary conditions for finite element model of head-neck-torso complex. In order to complement the model of head-neck-torso complex; the head-neck model is connected to the torso part of HYBRID-III model. After the head-neck part is connected to the torso part, the connected model is validated with the dynamical responses of the head-neck complex during axial impact loading [3]; additionally, the muscles are attached to the head-neck-torso model according to the published origin and insertion data, and muscles attached include hyoid, semispinalis capitis, splenius capitis, sternocleidomastoid, and trapezius presently [4].The equations of equilibrium, constraints, gravity, and the object function are derived according to the four collisions in ADAMS simulation (7586N at 0.22s, 15874N at 0.85s; 6976N at 0.26s; 213N at 0.6 s, 650N at 1.4 s; 9391N at 2.1s). The object function is determined, assuming that only two states of neck muscle activation dominate the behavior during collisions between motorcycle and car. One is the relaxed state, and thus the object function can be minimizing the fatigue; the other is tensed state, and thus the object can be maximizing the endurance. Once these are determined, the LS-OPT is used to optimize the initial conditions of the muscle activation of each muscle [5]. Both Journal of Biomechanics 40(S2)
Figure 1: The head-neck-torso model with muscles, which include hyoid, semispinalis capitis, splenius capitis, stermocleidomastoid, and trapezius muscles. REFERENCES 1. Wu CY, Master Thesis, Institute of Biomedical Eng., National Yang Ming University, Taiwan, 2003. 2. Lee IH, et al., IJAT, Vol. 5, No. 1, pp. 33-46, 2004. 3. Nightingale, et al, J Biomech, Vol. 29, No. 3, pp. 307-318, 1996 4. Oi Nelson, et al, Stapp Car Crash Journal, Vol. 48, pp. 397-417, 2004 5. Chancey VC, et al, Stapp Car Crash Journal, Vol. 47, pp. 135-153, 2003 ACKNOWLEDGEMENTS This study is supported by National Science Council of R.O.C Grant- NSC94-2213-E010-007
XXI ISB Congress, Poster Sessions, Thursday 5 July 2007