Centre for Sport Research, School of Exercise and Nutrition Sciences, Deakin University, Waurn Ponds, VIC, Australia.
PeerJ. 2023 Feb 16;11:e14708. doi: 10.7717/peerj.14708. eCollection 2023.
Variation in tibia geometry is a risk factor for tibial stress fractures. Geometric variability in bones is often quantified using statistical shape modelling. Statistical shape models (SSM) offer a method to assess three-dimensional variation of structures and identify the source of variation. Although SSM have been used widely to assess long bones, there is limited open-source datasets of this kind. Overall, the creation of SSM can be an expensive process, that requires advanced skills. A publicly available tibia shape model would be beneficial as it enables researchers to improve skills. Further, it could benefit health, sport and medicine with the potential to assess geometries suitable for medical equipment, and aid in clinical diagnosis. This study aimed to: (i) quantify tibial geometry using a SSM; and (ii) provide the SSM and associated code as an open-source dataset.
Lower limb computed tomography (CT) scans from the right tibia-fibula of 30 cadavers (male = 20, female = 10) were obtained from the New Mexico Decedent Image Database. Tibias were segmented and reconstructed into both cortical and trabecular sections. Fibulas were segmented as a singular surface. The segmented bones were used to develop three SSM of the: (i) tibia; (ii) tibia-fibula; and (iii) cortical-trabecular. Principal component analysis was applied to obtain the three SSM, with the principal components that explained 95% of geometric variation retained.
Overall size was the main source of variation in all three models accounting for 90.31%, 84.24% and 85.06%. Other sources of geometric variation in the tibia surface models included overall and midshaft thickness; prominence and size of the condyle plateau, tibial tuberosity, and anterior crest; and axial torsion of the tibial shaft. Further variations in the tibia-fibula model included midshaft thickness of the fibula; fibula head position relative to the tibia; tibia and fibula anterior-posterior curvature; fibula posterior curvature; tibia plateau rotation; and interosseous width. The main sources of variation in the cortical-trabecular model other than general size included variation in the medulla cavity diameter; cortical thickness; anterior-posterior shaft curvature; and the volume of trabecular bone in the proximal and distal ends of the bone.
Variations that could increase the risk of tibial stress injury were observed, these included general tibial thickness, midshaft thickness, tibial length and medulla cavity diameter (indicative of cortical thickness). Further research is needed to better understand the effect of these tibial-fibula shape characteristics on tibial stress and injury risk. This SSM, the associated code, and three use examples for the SSM have been provided in an open-source dataset. The developed tibial surface models and statistical shape model will be made available for use at: https://simtk.org/projects/ssm_tibia.
胫骨几何形状的变化是胫骨应力性骨折的一个风险因素。骨骼的几何形状变化通常使用统计形状建模来量化。统计形状模型（SSM）提供了一种评估结构三维变化和确定变化来源的方法。尽管 SSM 已被广泛用于评估长骨，但这种类型的公开数据集有限。总体而言，创建 SSM 可能是一个昂贵的过程，需要先进的技能。一个可用的胫骨形状模型将是有益的，因为它使研究人员能够提高技能。此外，它可以通过评估适合医疗设备的几何形状来使健康、运动和医学受益，并有助于临床诊断。本研究旨在：（i）使用 SSM 量化胫骨几何形状；（ii）提供 SSM 及其相关代码作为开源数据集。
从新墨西哥死者图像数据库中获得 30 具尸体（男性 20 例，女性 10 例）右侧胫骨-腓骨的下肢计算机断层扫描（CT）扫描。将胫骨分段并重建为皮质和小梁部分。腓骨被分段为单个表面。使用分段骨骼来开发三种 SSM：（i）胫骨；（ii）胫骨-腓骨；和（iii）皮质-小梁。应用主成分分析获得三个 SSM，保留解释 95%几何变化的主要成分。
总体大小是所有三个模型的主要变化来源，占 90.31%、84.24%和 85.06%。胫骨表面模型中其他几何变化的来源包括整体和中轴厚度；髁突平台、胫骨结节和前嵴的突出度和大小；以及胫骨轴的轴向扭转。胫骨-腓骨模型中的进一步变化包括腓骨中段厚度；腓骨头相对于胫骨的位置；胫骨和腓骨前后曲率；腓骨后曲率；胫骨平台旋转；和骨间宽度。皮质-小梁模型中除总体大小以外的主要变化来源包括髓腔直径变化；皮质厚度；骨干前后曲率；以及骨骼近端和远端的小梁骨体积。
观察到可能增加胫骨应力性损伤风险的变化，包括胫骨总体厚度、中段厚度、胫骨长度和髓腔直径（提示皮质厚度）。需要进一步研究以更好地了解这些胫骨-腓骨形状特征对胫骨应力和损伤风险的影响。该 SSM、相关代码和 SSM 的三个使用示例已在开源数据集中提供。开发的胫骨表面模型和统计形状模型将可在以下网址使用：https://simtk.org/projects/ssm_tibia。
