Koehle Michael J, Hull M L
Biomedical Engineering Program and Department of Mechanical Engineering, University of California, Davis, CA 95616, USA.
J Biomech Eng. 2010 Jan;132(1):011007. doi: 10.1115/1.3148192.
The usefulness of forward dynamic simulations to studies of human motion is well known. Although the musculoskeletal models used in these studies are generic, the modeling of specific components, such as the knee joint, may vary. Our two objectives were (1) to investigate the effects of three commonly used knee models on forward dynamic simulation results, and (2) to study the sensitivity of simulation results to variations in kinematics for the most commonly used knee model. To satisfy the first objective, three different tibiofemoral models were incorporated into an existing forward dynamic simulation of recumbent pedaling, and the resulting kinematics, pedal forces, muscle forces, and joint reaction forces were compared. Two of these models replicated the rolling and sliding motion of the tibia on the femur, while the third was a simple pin joint. To satisfy the second objective, variations in the most widely used of the three knee models were created by adjusting the experimental data used in the development of this model. These variations were incorporated into the pedaling simulation, and the resulting data were compared with the unaltered model. Differences between the two rolling-sliding models were smaller than differences between the pin-joint model and the rolling-sliding models. Joint reactions forces, particularly at the knee, were highly sensitive to changes in knee joint model kinematics, as high as 61% root mean squared difference, normalized by the corresponding peak force of the unaltered reference model. Muscle forces were also sensitive, as high as 30% root mean squared difference. Muscle excitations were less sensitive. The observed changes in muscle force and joint reaction forces were caused primarily by changes in the moment arms and musculotendon lengths of the quadriceps. Although some level of inaccuracy in the knee model may be acceptable for calculations of muscle excitation timing, a representative model of knee kinematics is necessary for accurate calculation of muscle and joint reaction forces.
正向动力学模拟在人体运动研究中的作用是众所周知的。尽管这些研究中使用的肌肉骨骼模型是通用的，但特定组件（如膝关节）的建模可能会有所不同。我们的两个目标是：（1）研究三种常用膝关节模型对正向动力学模拟结果的影响；（2）研究最常用膝关节模型的模拟结果对运动学变化的敏感性。为了实现第一个目标，将三种不同的胫股模型纳入现有的卧位蹬踏正向动力学模拟中，并比较由此产生的运动学、踏板力、肌肉力和关节反作用力。其中两种模型复制了胫骨在股骨上的滚动和滑动运动，而第三种是简单的销关节。为了实现第二个目标，通过调整用于开发该模型的实验数据，对三种膝关节模型中使用最广泛的模型进行了变化处理。将这些变化纳入蹬踏模拟中，并将所得数据与未改变的模型进行比较。两个滚动 - 滑动模型之间的差异小于销关节模型与滚动 - 滑动模型之间的差异。关节反作用力，特别是在膝关节处，对膝关节模型运动学的变化高度敏感，根均方差异高达61%，以未改变的参考模型的相应峰值力进行归一化。肌肉力也很敏感，根均方差异高达30%。肌肉兴奋度不太敏感。观察到的肌肉力和关节反作用力的变化主要是由股四头肌的力臂和肌腱长度的变化引起的。尽管膝关节模型中的一定程度的不准确性对于肌肉兴奋时间的计算可能是可以接受的，但为了准确计算肌肉和关节反作用力，需要一个具有代表性的膝关节运动学模型。
