基于OpenSim的腰部肌骨系统在体前屈状态下生物力学分析

OpenSim-Based Biomechanical Analysis of Lumbar Musculoskeletal System under Forward Flexion

目的基于OpenSim软件建立完善的腰部肌骨系统模型,深入了解体前屈状态下腰部肌群的受力情况。方法在软件现有腰部肌骨模型基础上,通过修改椎间约束,将腰椎还原为六自由度模型。同时,根据Thelen模型对肌肉参数进行修改,建立30岁成年人和70岁老年人肌肉模型,并添加椎间刚度矩阵和等效集中力表征的腹压模型。针对体前屈状态,探究手臂摆动、运动快慢、腹压改变、肌肉老化等因素对腰部九大肌群受力的影响。结果建立了包含九大腰部肌群的多刚体肌骨系统模型。基于前屈0°～70°的计算发现,手臂的摆动会明显减少腰大肌和腹外斜肌的受力,在完成前屈70°并恢复直立时,运动时间从5 s减小至2.5 s会明显增加腰大肌、腹外斜肌、腹直肌和竖脊肌的受力;其中,在5 s运动情况下,增加腹压能减少腰大肌的受力,而相应的腹外斜肌、腹内斜肌和腹横肌受力则有所增加。在2.5 s运动情况下对比不同状态下30、70岁两种肌肉模型的计算结果,没有发现明显区别。结论所建模型有效地分析了腰部肌群的受力情况,随着基本理论的更加完善,其在运动力学和康复医疗的应用前景十分广阔。

Objective Based on OpenSim platform,an improved musculoskeletal model was developed to analyze the force of lumbar muscle groups under forward flexion.Methods The existing lumbar musculoskeletal model was improved via modifying constraints of lumbar vertebrae to restore them into 6 degrees of freedom(DOF).The 30 year-old and 70 year-old muscle models were established respectively by adjusting muscle parameters according to Thelen’s model,adding stiffness matrixes and abdominal pressure(AP)characterized by concentrated force to investigate the effects of arm swing,movement velocity,varying AP and muscle aging on the force distribution of 9 lumbar muscle groups during forward flexion.Results A multi-body musculoskeletal model with 9 lumbar muscle groups was developed.Based on the computations of 0°-70°flexion,the results showed that arm swing reduced the force of psoas and external oblique abdominis,while under the movement of forward flexing to 70°and returning up-right,the force of psoas,erector spinae,rectus and external oblique abdominis obviously in-creased,when the time of flexing-returning process was reduced from 5 s to 2.5 s,and in the 5 s case,increasing AP reduced the force of psoas but increased the force of transversus,internal and external oblique abdominis.In the 2.5 s case,there was no obvious difference between the 30 year-old and 70 year-old muscle models under different conditions.Conclusions The developed model provides an effective method to analyze the force of lumbar spine and muscles,and it certainly shows a potential application in the fields of kinematic mechanics and rehabilitation engineering with further development of basic theory.