Woltring H J, Long K, Osterbauer P J, Fuhr A W
Whiplash Analysis Incorporation, Phoenix, AZ 85018.
J Biomech. 1994 Dec;27(12):1415-32. doi: 10.1016/0021-9290(94)90192-9.
To date, the diagnosis of whiplash injuries has been very difficult and largely based on subjective, clinical assessment. The work by Winters and Peles Multiple Muscle Systems--Biomechanics and Movement Organization. Springer, New York (1990) suggests that the use of finite helical axes (FHAs) in the neck may provide an objective assessment tool for neck mobility. Thus, the position of the FHA describing head-trunk motion may allow discrimination between normal and pathological cases such as decreased mobility in particular cervical joints. For noisy, unsmoothed data, the FHAs must be taken over rather large angular intervals if the FHAs are to be reconstructed with sufficient accuracy; in the Winters and Peles study, these intervals were approximately 10 degrees. in order to study the movements' microstructure, the present investigation uses instantaneous helical axes (IHAs) estimated from low-pass smoothed video data. Here, the small-step noise sensitivity of the FHA no longer applies, and proper low-pass filtering allows estimation of the IHA even for small rotation velocity omega of the moving neck. For marker clusters mounted on the head and trunk, technical system validation showed that the IHAs direction dispersions were on the order of one degree, while their position dispersions were on the order of 1 mm, for low-pass cut-off frequencies of a few Hz (the dispersions were calculated from omega-weighted errors, in order to account for the adverse effects of vanishing omega). Various simple, planar models relating the instantaneous, 2-D centre of rotation with the geometry and kinematics of a multi-joint neck model are derived, in order to gauge the utility of the FHA and IHA approaches. Some preliminary results on asymptomatic and pathological subjects are provided, in terms of the 'ruled surface' formed by sampled IHAs and of their piercing points through the mid-sagittal plane during a prescribed flexion-extension movement of the neck.
迄今为止，挥鞭样损伤的诊断一直非常困难，且很大程度上基于主观的临床评估。温特斯和佩莱斯所著的《多肌肉系统——生物力学与运动组织》（施普林格出版社，纽约，1990年）表明，颈部有限螺旋轴（FHA）的应用可能为颈部活动度提供一种客观评估工具。因此，描述头颈部运动的FHA位置可能有助于区分正常与病理情况，比如特定颈椎关节活动度降低的情况。对于噪声大、未平滑处理的数据，如果要足够精确地重建FHA，则必须在相当大的角度间隔上获取数据；在温特斯和佩莱斯的研究中，这些间隔约为10度。为了研究运动的微观结构，本研究采用从低通平滑视频数据中估计出的瞬时螺旋轴（IHA）。在此，FHA对小步噪声的敏感性不再适用，适当的低通滤波即使在颈部运动角速度ω较小时也能估计出IHA。对于安装在头部和躯干上的标记簇，技术系统验证表明，对于几赫兹的低通截止频率，IHA方向离散度约为1度，而其位置离散度约为1毫米（离散度是根据ω加权误差计算得出的，以考虑ω趋近于零时的不利影响）。推导了各种简单的平面模型，将瞬时二维旋转中心与多关节颈部模型的几何结构和运动学联系起来，以评估FHA和IHA方法的效用。就采样IHA形成的“直纹面”及其在颈部规定屈伸运动过程中通过中矢状面的穿刺点，给出了无症状和病理受试者的一些初步结果。
