Apostolopoulos Vasileios, Tomáš Tomáš, Boháč Petr, Marcián Petr, Mahdal Michal, Valoušek Tomáš, Janíček Pavel, Nachtnebl Luboš
First Department of Orthopaedic Surgery, St. Anne's University Hospital and Faculty of Medicine, Masaryk University, Brno, Czech Republic.
Institute of Solid Mechanics, Mechatronics and Biomechanics, Faculty of Mechanical Engineering, Brno University of Technology, Brno, Czech Republic.
Comput Methods Programs Biomed. 2022 Jun;220:106834. doi: 10.1016/j.cmpb.2022.106834. Epub 2022 Apr 25.
Total knee arthroplasty (TKA) with modern all-polyethylene tibial (APT) components has shown high long-term survival rates and comparable results to those with metal-backed tibial components. Nevertheless, APT components are primarily recommended for older and low-demand patients. There are no evidence-based biomechanical guidelines for orthopaedic surgeons to determine the appropriate lower age limit for implantation of APT components. A biomechanical analysis was assumed to be suitable to evaluate the clinical results in patients under 70 years. The scope of this study was to determine biomechanically the appropriate lower age limit for implantation of APT components.
To generate data of the highest possible quality, the geometry of the computational models was created based on computed tomography (CT) images of a representative patient. The cortical bone tissue model distinguishes the change in mechanical properties described in three parts from the tibial cut. The cancellous bone material model has a heterogeneous distribution of mechanical properties. The values used to determine the material properties of the tissues were obtained from measurements of a CT dataset comprising 45 patients.
Computational modeling showed that in the majority of the periprosthetic volume, the von Mises strain equivalent ranges from 200 to 2700 με; these strain values induce bone modeling and remodeling. The highest measured deformation value was 2910 με. There was no significant difference in the induced mechanical response between bone models of the 60-year and 70-year age groups, and there was <3% difference from the 65-year age group.
Considering in silico limitations, we suggest that APT components could be conveniently used on a bone with mechanical properties of the examined age categories. Under defined loading conditions, implantation of TKA with APT components is expected to induce modeling and remodeling of the periprosthetic tibia. Following clinical validation, the results of our study could modify the indication criteria of the procedure, and lead to more frequent implantation of all-polyethylene TKA in younger patients.
采用现代全聚乙烯胫骨（APT）组件的全膝关节置换术（TKA）已显示出较高的长期生存率，且结果与金属背衬胫骨组件相当。然而，APT组件主要推荐用于老年和低需求患者。目前尚无基于证据的生物力学指南供骨科医生确定APT组件植入的合适下限年龄。生物力学分析被认为适合评估70岁以下患者的临床结果。本研究的范围是从生物力学角度确定APT组件植入的合适下限年龄。
为生成尽可能高质量的数据，基于一名代表性患者的计算机断层扫描（CT）图像创建计算模型的几何结构。皮质骨组织模型从胫骨截骨处区分出三个部分描述的力学性能变化。松质骨材料模型具有力学性能的不均匀分布。用于确定组织材料性能的值取自包含45名患者的CT数据集测量结果。
计算模型显示，在假体周围大部分区域，冯·米塞斯应变当量范围为200至2700με；这些应变值会引发骨塑形和重塑。测得的最高变形值为2910με。60岁和70岁年龄组的骨模型之间诱发的力学反应无显著差异，与65岁年龄组的差异小于3%。
考虑到计算机模拟的局限性，我们建议APT组件可方便地用于具有所检查年龄类别力学性能的骨骼。在规定的加载条件下，植入带有APT组件的TKA预计会引发假体周围胫骨的塑形和重塑。经过临床验证，我们的研究结果可能会修改该手术的适应证标准，并导致全聚乙烯TKA在年轻患者中更频繁地植入。
