| With the rapid development of the automobile industry,the incidence rate of various diseases related to cars increase year by year when people enjoy the convenience provided by automobile.Meanwhile,the health problem of drivers is attracted more and more attention.The research shows that the case rate of low back pain among drivers is approximately 57%—82%and higher than non-drivers.Furthermore,the prevalence rate of drivers who drive heavy engineering vehicles is as high as 80%.The low back pain belongs to one of the common diseases of drivers.The vibration during vehicles running has a great influence on human spine.And the reason is that the vibration excitation can set up spinal resonance during running.At this moment,the influence and damage of spine increase,which accelerate degeneration of the intervertebral disc and lead to the intensification of low back pain.In addition,the serious degeneration intervertebral disc can only treated by operation because of the irreversibility of degenerative disc.However,the previous study shows that the traditional operation scheme,which is implanting the pedicle screw,may affect the physiological function of spine.Therefore,in this paper we investigate the effect vibration characteristics effect of human spine after implanting instrument and optimal design of implantable instrument aiming at the low back pain problem of drivers.The main researches are as follows:Firstly,human healthy and degenerative lumbar spine models are studied.The human healthy lumbar spine three-dimensional model is reconstruct by CT scans technique and the software MIMICS.Also,the finite element mesh model including various lumbar tissue and structure is defined using the software ANSA.In addition,we create a moderate degenerative lumbar spine model according to the grade of degenerative disc and physiological characteristics.The two models are verified based on range of motion(ROM)in the lumbar segment using the software ABAQUS.The result shows that the model in this paper is reasonable and effective.Secondly,the operative lumbar spine implanting with Coflex-F device is analyzed using finite element method in terms of static and dynamic state.According to the surgical operation requirements,we create the model with implanted instrument and compare with ROM from the simulation result.And the result shows that implanting Coflex-F device can stabilize in all motions.Moreover,the result of modal analysis and random response analysis indicate that implanting Coflex-F device can protect the surgical segment disc but can accelerate the degeneration of the intervertebral disc in the adjacent segments when the lumbar spine resonates.Thirdly,the interspinous implanting device Coflex-F is redesigned using topology optimization.On the basis of static analysis result,we define the whole lumbar spine model stiffness as the optimization objective,the volume of Coflex-F as constraint condition to optimize.And the new device is redesign and validated according to the optimization result.The new design Coflex-NEW cannot only satisfied strength requirements but also reduce the risk of the implanted segment spinous process fracture and the instrument damage. |
