Taylor William R, Ehrig Rainald M, Duda Georg N, Schell Hanna, Seebeck Petra, Heller Markus O
Center for Musculoskeletal Surgery, Charité-University Medicine Berlin, Augustenburger Platz 1, D-13353 Berlin, Germany.
J Orthop Res. 2005 Jul;23(4):726-34. doi: 10.1016/j.orthres.2005.02.006. Epub 2005 Mar 29.
Accurate measurement of underlying bone positions is important for the understanding of normal movement and function, as well as for addressing clinical musculoskeletal or post-injury problems. Non-invasive measurement techniques are limited by the analysis technique and movement of peripheral soft tissues that can introduce significant measurement errors in reproducing the kinematics of the underlying bones when using external skin markers. Reflective markers, skeletally mounted to the right hind limb of three Merino-mix sheep were measured simultaneously with markers attached to the skin of each segment, during repetitions of gait trials. The movement of the skin markers relative to the underlying bone positions was then assessed using the Point Cluster Technique (PCT), raw averaging and the Optimal Common Shape Technique (OCST), a new approach presented in this manuscript. Errors in the position of the proximal joint centre, predicted from the corresponding skin markers, were shown to be phasic and strongly associated with the amount soft tissue coverage, averaging 8.5 mm for the femur, 2.8 for the tibia and 2.0 for the metatarsus. Although the results show a better prediction of bone kinematics associated with the Optimal Common Shape Technique, these errors were large for all three assessment techniques and much greater than the differences between the various techniques. Whilst individual markers moved up to 4 mm from the optimal marker set configuration, average peak errors of up to 16, 5 and 3 mm (hip, knee and tibio-metatarsal joints respectively) were observed, suggesting that a large amount of kinematic noise is produced from the synchronous shifting of marker sets, potentially as a result of underlying muscle firing and the inertial effects of heel impact. Current techniques are therefore limited in their ability to determine the kinematics of underlying bones based on skin markers, particularly in segments with more pronounced soft tissue coverage.
准确测量骨骼的基础位置对于理解正常运动和功能以及解决临床肌肉骨骼问题或损伤后问题至关重要。非侵入性测量技术受到分析技术和周围软组织运动的限制，在使用外部皮肤标记物重现骨骼基础运动学时，这些因素可能会引入显著的测量误差。在三只美利奴杂交羊的右后肢骨骼上安装反光标记物，并在步态试验重复过程中，同时测量附着在每个节段皮肤上的标记物。然后使用点簇技术（PCT）、原始平均法和最优共同形状技术（OCST，本文提出的一种新方法）评估皮肤标记物相对于骨骼基础位置的运动。由相应皮肤标记物预测的近端关节中心位置误差呈现阶段性，且与软组织覆盖量密切相关，股骨平均误差为8.5毫米，胫骨为2.8毫米，跖骨为2.0毫米。尽管结果表明最优共同形状技术对骨骼运动学的预测更好，但所有三种评估技术的这些误差都很大，且远大于不同技术之间的差异。虽然单个标记物相对于最优标记物集配置移动了多达4毫米，但观察到平均峰值误差分别高达16毫米、5毫米和3毫米（分别为髋关节、膝关节和胫跖关节），这表明标记物集的同步移动会产生大量运动噪声，这可能是由于潜在的肌肉活动和足跟撞击的惯性效应所致。因此，当前技术在基于皮肤标记物确定骨骼基础运动学方面的能力有限，尤其是在软组织覆盖更明显的节段。
