Amsterdam UMC, Vrije Universiteit Amsterdam, Rehabilitation Medicine, Amsterdam Movement Sciences, de Boelelaan 1117, Amsterdam, the Netherlands; Amsterdam UMC, University of Amsterdam, Radiology and Nuclear Medicine, Medical Imaging Quantification Center (MIQC), Amsterdam Movement Sciences, Meibergdreef 9, Amsterdam, the Netherlands.
Amsterdam UMC, University of Amsterdam, Radiology and Nuclear Medicine, Medical Imaging Quantification Center (MIQC), Amsterdam Movement Sciences, Meibergdreef 9, Amsterdam, the Netherlands; Amsterdam UMC, University of Amsterdam, Biomedical Engineering and Physics, Amsterdam Movement Sciences, Meibergdreef 9, Amsterdam, the Netherlands.
J Biomech. 2021 May 7;120:110359. doi: 10.1016/j.jbiomech.2021.110359. Epub 2021 Mar 6.
Movement of skin markers with respect to their underlying bone (i.e. soft tissue artifacts (STAs)) might corrupt the accuracy of marker-based movement analyses. This study aims to quantify STAs in 3D for foot markers and their effect on multi-segment foot kinematics as calculated by the Oxford and Rizzoli Foot Models (OFM, RFM). Fifteen subjects with asymptomatic feet were seated on a custom-made loading device on a computed tomography (CT) table, with a combined OFM and RFM marker set on their right foot. One unloaded reference CT-scan with neutral foot position was performed, followed by 9 loaded CT-scans at different foot positions. The 3D-displacement (i.e. STA) of each marker in the underlying bone coordinate system between the reference scan and other scans was calculated. Subsequently, segment orientations and joint angles were calculated from the marker positions according to OFM and RFM definitions with and without STAs. The differences in degrees were defined as the errors caused by the marker displacements. Markers on the lateral malleolus and proximally on the posterior aspect of the calcaneus showed the largest STAs. The hindfoot-shank joint angle was most affected by STAs in the most extreme foot position (40° plantar flexion) in the sagittal plane for RFM (mean: 6.7°, max: 11.8°) and the transverse plane for OFM (mean: 3.9°, max: 6.8°). This study showed that STAs introduce clinically relevant errors in multi-segment foot kinematics. Moreover, it identified marker locations that are most affected by STAs, suggesting that their use within multi-segment foot models should be reconsidered.
皮肤标记相对于其下方骨骼（即软组织伪影（STAs））的运动可能会影响基于标记的运动分析的准确性。本研究旨在量化足部标记的 3D STA，并研究其对基于牛津和里兹利足部模型（OFM、RFM）计算的多节段足部运动学的影响。15 名无症状足部的受试者坐在 CT 台上的定制加载设备上，在右脚贴上 OFM 和 RFM 组合标记。首先进行中立足部位置的未加载参考 CT 扫描，然后进行 9 次不同足部位置的加载 CT 扫描。在参考扫描和其他扫描之间，在基础骨骼坐标系中计算每个标记的 3D 位移（即 STA）。随后，根据 OFM 和 RFM 的定义，无论是否存在 STA，根据标记位置计算节段方向和关节角度。以度为单位的差异定义为标记位移引起的误差。外踝和跟骨后上侧的标记显示出最大的 STA。在矢状面最极端的足部位置（40°跖屈）和 RFM 的横断面上（平均：6.7°，最大：11.8°），跟骨-小腿关节角度受 STA 的影响最大，而在 OFM 的横断面上（平均：3.9°，最大：6.8°）。本研究表明，STA 会在多节段足部运动学中引入临床相关的误差。此外，它确定了受 STA 影响最大的标记位置，这表明应重新考虑在多节段足部模型中使用这些标记。
