Department of Biomechanical Engineering, Delft University of Technology (TU Delft), Delft, The Netherlands.
Department of Orthopedics, UMC Utrecht, Utrecht, The Netherlands.
J Anat. 2019 Jan;234(1):132-144. doi: 10.1111/joa.12900. Epub 2018 Nov 4.
The bones forming the talocrural joint (TCJ) and subtalar joint (STJ) are often assumed to be bilaterally symmetric. Therefore, the contralateral limb (i.e. the fibula, tibia, calcaneus and talus) is used as a template or an intra-subject control in clinical and research practice. However, the validity of the symmetry assumption is controversial, because insufficient information is available on the shape variations and bilateral (a)symmetry of the fibula, tibia, calcaneus and talus. Using three-dimensional spatially dense sampled representations of bone shapes extracted from bilateral computed tomography scans of 66 individuals (55 male, mean age: 61 ± 10 years; 11 female, mean age: 53 ± 15 years), we analyzed whether: (i) similar shape patterns exist in the left and right bones of the same type; (ii) gender has an effect on bone shape variations; (iii) intra-subject shape variation is smaller than that of inter-subject for a given shape variance direction. For the first set of analyses, all left and right instances of the same type of bone were considered as two separate groups, and statistically compared with each other on multiple aspects including group location (central tendency), variance-covariance scale (dispersion) and orientation (covariance structure) using distance-based permutational tests. For the second and third sets of analyses, all left and right bones of the same type were pooled into one group, and shape variations in the TCJ and STJ bones were extracted using principal component analysis. The effects of gender on age-adjusted bone shape differences were assessed using an analysis of covariance. Moreover, intra-class correlation was employed to evaluate intra- and inter-subject bone shape variations. For each bone type, both sides had similar shape patterns (P -values > 0.05). After Bonferroni adjustment, gender led to shape differences, which were mainly in the lateral and medial condyles of the tibia (P = 0.003), the length and height of the calcaneus (P < 0.001), the posterior and anterior talar articular surfaces of the calcaneus (P = 0.001), and in the posterior aspect of the talus (P = 0.001). Intra-subject shape variations in the tibial tuberosity together with the diameter of the tibia, and the curvature of the fibula shaft and the diameter of the fibula were as high as those of inter-subject. This result suggests that the shape symmetry assumption could be violated for some specific shape variations in the fibula and tibia.
距下关节和距小腿关节的骨骼通常被认为是双侧对称的。因此,在临床和研究实践中,通常会使用对侧肢体(即腓骨、胫骨、跟骨和距骨)作为模板或个体内对照。然而,对称性假设的有效性存在争议,因为目前还缺乏关于腓骨、胫骨、跟骨和距骨的形状变化和双侧(非)对称性的充分信息。我们使用从 66 个人(55 名男性,平均年龄:61±10 岁;11 名女性,平均年龄:53±15 岁)的双侧 CT 扫描中提取的骨骼形状的三维空间密集采样表示,分析了以下内容:(i)相同类型的左右骨骼是否存在相似的形状模式;(ii)性别是否会影响骨骼形状变化;(iii)对于给定的形状方差方向,个体内的形状变化是否小于个体间的变化。对于第一组分析,将同一类型的所有左右骨骼实例视为两个独立的组,并使用基于距离的置换检验,在多个方面(包括组位置[中心趋势]、方差协方差尺度[离散度]和方向[协方差结构])相互进行统计比较。对于第二组和第三组分析,将同一类型的所有左右骨骼合并到一个组中,并使用主成分分析提取距下关节和距小腿关节骨骼的形状变化。使用协方差分析评估性别对年龄调整后骨骼形状差异的影响。此外,还使用组内相关来评估个体内和个体间的骨骼形状变化。对于每种骨骼类型,双侧都具有相似的形状模式(P 值>0.05)。经过 Bonferroni 调整后,性别导致了形状差异,这些差异主要位于胫骨的内外侧髁(P=0.003)、跟骨的长度和高度(P<0.001)、跟骨的后距和前距关节面(P=0.001)以及距骨的后表面(P=0.001)。胫骨结节和胫骨直径、腓骨骨干曲率和腓骨直径的个体内形状变化与个体间的变化一样高。这一结果表明,在某些特定的腓骨和胫骨形状变化中,形状对称假设可能会被违反。