INSIGNEO Institute for in silico Medicine, The University of Sheffield, Sheffield, UK; Department of Mechanical Engineering, The University of Sheffield, Sheffield, UK.
J Biomech. 2022 May;136:111072. doi: 10.1016/j.jbiomech.2022.111072. Epub 2022 Apr 2.
Skeletal computational models relying on global optimisation are widely used alongside gait analysis for the estimate of joint kinematics, but the degrees of freedom (DOFs) and axes definitions to model the ankle complex are still debated. The aim of this paper is to establish whether ankle modelling choices would also critically affect the estimate of the other joints' kinematics. Gait and MRI data from fifteen juvenile participants were used to implement three ankle joint models (M1, one-DOF sagittal motion; M2, two-DOFs sagittal and frontal motions; M3, three-DOFs) as part of a full lower-limb skeletal model. Differences in lower-limb joint and foot progression angles calculated using global optimisation were evaluated both at individual and group level. Furthermore, the influence of these differences on the correlations between joints and on the calculations of the root mean square deviation (RMSD) were investigated. Inter-model variations at individual level reached up to 4.2°, 9.1°, and 15.0° for hip flexion, adduction, and rotation, respectively, and up to 6.5° for knee flexion. Despite the tibiotalar axis being the same for all models, up to 19.3° (9.1° on average) larger dorsiflexion was found at push-off with M2. A stronger correlation between foot progression and ankle and knee sagittal movements was found for M1. Finally, RMSD led to inconsistent ranking of the participants when using different models. In conclusion, the choice of the ankle joint model affects the estimates of proximal lower-limb joint kinematics, which should discourage comparisons across datasets built with different models.
骨骼计算模型依赖于全局优化，与步态分析一起广泛用于估计关节运动学，但模型中踝关节复合体的自由度（DOF）和轴定义仍存在争议。本文的目的是确定踝关节建模选择是否也会严重影响其他关节运动学的估计。使用十五名青少年参与者的步态和 MRI 数据，实施了三个踝关节模型（M1，一个自由度矢状运动；M2，两个自由度矢状和额状运动；M3，三个自由度），作为完整下肢骨骼模型的一部分。使用全局优化计算的下肢关节和足推进角度的个体和组水平差异进行了评估。此外，还研究了这些差异对关节之间相关性以及根均方根偏差（RMSD）计算的影响。个体水平的模型间差异在髋关节屈曲、内收和旋转方面分别达到 4.2°、9.1°和 15.0°，在膝关节屈曲方面达到 6.5°。尽管所有模型的胫距关节都相同，但 M2 在蹬离时发现足背屈增加了高达 19.3°（平均 9.1°）。M1 中发现了足推进与踝关节和膝关节矢状运动之间更强的相关性。最后，RMSD 导致使用不同模型时参与者的排名不一致。总之，踝关节模型的选择会影响近端下肢关节运动学的估计，这应该阻止使用不同模型构建的数据集之间的比较。
