Bisseling Rob W, Hof At L
Center for Human Movement Sciences, University of Groningen, P.O. Box 196, 9700 AD Groningen, The Netherlands.
J Biomech. 2006;39(13):2438-44. doi: 10.1016/j.jbiomech.2005.07.021. Epub 2005 Oct 4.
In the standard inverse dynamic method, joint moments are assessed from ground reaction force data and position data, where segmental accelerations are calculated by numerical differentiation of position data after low-pass filtering. This method falls short in analyzing the impact phase, e.g. landing after a jump, by underestimating the contribution of the segmental accelerations to the joint moment assessment. This study tried to improve the inverse dynamics method for the assessment of knee moment by evaluating different cutoff frequencies in low-pass filtering of position data on the calculation of knee moment. Next to this, the effect of an inclusion of direct measurement of segmental acceleration using accelerometers to the inverse dynamics was evaluated. Evidence was obtained that during impact, the contribution of the ground reaction force to the sagittal knee moment was neutralized by the moments generated by very high segmental accelerations. Because the accelerometer-based method did not result in the expected improvement of the knee moment assessment during activities with high impacts, it is proposed to filter the ground reaction force with the same cutoff frequency as the calculated accelerations. When this precaution is not taken, the impact peaks in the moments can be considered as artifacts. On the basis of these findings, we recommend in the search to biomechanical explanations of chronic overuse injuries, like jumper's knee, not to consider the relation with impact peak force and impact peak moment.
在标准的逆动力学方法中，关节力矩是根据地面反作用力数据和位置数据来评估的，其中节段加速度是通过对低通滤波后的位置数据进行数值微分计算得出的。该方法在分析冲击阶段（例如跳跃后着地）时存在不足，因为它低估了节段加速度对关节力矩评估的贡献。本研究试图通过评估在计算膝关节力矩时对位置数据进行低通滤波的不同截止频率，来改进用于评估膝关节力矩的逆动力学方法。除此之外，还评估了将使用加速度计直接测量节段加速度纳入逆动力学的效果。有证据表明，在冲击过程中，地面反作用力对矢状面膝关节力矩的贡献被非常高的节段加速度产生的力矩所抵消。由于基于加速度计的方法在高冲击活动中并未导致膝关节力矩评估得到预期的改善，因此建议使用与计算出的加速度相同的截止频率对地面反作用力进行滤波。如果不采取这一预防措施，力矩中的冲击峰值可被视为伪影。基于这些发现，我们建议在寻找慢性过度使用损伤（如跳跃者膝）的生物力学解释时，不要考虑与冲击峰值力和冲击峰值力矩的关系。
