Ecole Polytechnique Fédérale de Lausanne, Laboratory of Movement Analysis and Measurement, CH-1015 Lausanne, Switzerland.
J Biomech. 2012 Jul 26;45(11):2041-5. doi: 10.1016/j.jbiomech.2012.05.018. Epub 2012 Jun 12.
The joint angles of multi-segment foot models have been primarily described using two mathematical methods: the joint coordinate system and the attitude vector. This study aimed to determine whether the angles obtained through these two descriptors are comparable, and whether these descriptors have similar sensitivity to experimental errors. Six subjects walked eight times on an instrumented walkway while the joint angles among shank, hindfoot, medial forefoot, and lateral forefoot were measured. The angles obtained using both descriptors and their sensitivity to experimental errors were compared. There was no overall significant difference between the ranges of motion obtained using both descriptors. However, median differences of more than 6° were noticed for the medial-lateral forefoot joint. For all joints and rotation planes, both descriptors provided highly similar angle patterns (median correlation coefficient: R>0.90), except for the medial-lateral forefoot angle in the transverse plane (median R=0.77). The joint coordinate system was significantly more sensitive to anatomical landmarks misplacement errors. However, the absolute differences of sensitivity were small relative to the joints ranges of motion. In conclusion, the angles obtained using these two descriptors were not identical, but were similar for at least the shank-hindfoot and hindfoot-medial forefoot joints. Therefore, the angle comparison across descriptors is possible for these two joints. Comparison should be done more carefully for the medial-lateral forefoot joint. Moreover, despite different sensitivities to experimental errors, the effects of the experimental errors on the angles were small for both descriptors suggesting that both descriptors can be considered for multi-segment foot models.
关节坐标系和姿态向量。本研究旨在确定这两个描述符获得的角度是否具有可比性，以及这些描述符对实验误差是否具有相似的敏感性。六名受试者在仪器化步行道上行走了八次，同时测量了小腿、后足、内侧前足和外侧前足的关节角度。比较了两种描述符获得的角度及其对实验误差的敏感性。虽然使用两种描述符获得的运动范围没有总体显著差异，但在中-外侧前足关节处注意到超过 6°的中值差异。对于所有关节和旋转平面，两种描述符都提供了高度相似的角度模式（中值相关系数：R>0.90），除了横断面上的中-外侧前足角（中值 R=0.77）。关节坐标系对解剖学标志错位误差的敏感性明显更高。然而，相对于关节的运动范围，灵敏度的绝对差异很小。总之，这两种描述符获得的角度并不完全相同，但对于至少小腿-后足和后足-内侧前足关节来说，它们是相似的。因此，对于这两个关节，可以跨描述符进行角度比较。对于中-外侧前足关节，应该更加小心地进行比较。此外，尽管对实验误差的敏感性不同，但实验误差对两种描述符角度的影响都很小，这表明这两种描述符都可以用于多节段足模型。
