Faculty of Biomedical Engineering, Amirkabir University of Technology, No. 350, Hafez Ave, Valiasr Square, 1591634311, Tehran, Iran.
Orthopaedic Research Center, Department of Orthopaedic Surgery, Mashhad University of Medical Sciences, Ghaem Hospital, Ahmad Abad Street, Mashhad, Iran.
Sci Rep. 2020 Dec 7;10(1):21319. doi: 10.1038/s41598-020-78188-3.
The distal femur is the predominant site for benign bone tumours and a common site for fracture following tumour removal or cementation. However, the lack of conclusive assessment criterion for post-operative fracture risk and appropriate devices for cement augmentation are serious concerns. Hence, a validated biomechanical tool was developed to assess bone strength, depending on the size and location of artificially created tumorous defects in the distal femora. The mechanics of the bone-cement interface was investigated to determine the main causes of reconstruction failure. Based on quantitative-CT images, non-linear and heterogeneous finite element (FE) models of human cadaveric distal femora with simulated tumourous defects were created and validated using in vitro mechanical tests from 14 cadaveric samples. Statistical analyses demonstrated a strong linear relationship (R = 0.95, slope = 1.12) with no significant difference between bone strengths predicted by in silico analyses and in vitro tests (P = 0.174). FE analyses showed little reduction in bone strength until the defect was 35% or more of epiphyseal volume, and reduction in bone strength was less pronounced for laterally located defects than medial side defects. Moreover, the proximal end of the cortical window and the most interior wall of the bone-cement interface were the most vulnerable sites for reconstruction failure.
股骨远端是良性骨肿瘤的主要发生部位，也是肿瘤切除或骨水泥加固后骨折的常见部位。然而，缺乏术后骨折风险的明确评估标准和适当的骨水泥增强装置是严重的问题。因此，开发了一种经过验证的生物力学工具，根据人工创建的股骨远端肿瘤性缺陷的大小和位置来评估骨强度。研究了骨-水泥界面的力学性能，以确定重建失败的主要原因。基于定量 CT 图像，使用来自 14 个尸体样本的体外力学测试，对具有模拟肿瘤性缺陷的人类尸体股骨远端的非线性和非均匀有限元 (FE) 模型进行了创建和验证。统计分析表明，具有肿瘤性缺陷的骨强度的预测值与体外测试之间存在很强的线性关系（R=0.95，斜率=1.12），且无统计学差异（P=0.174）。FE 分析表明，直到缺陷达到骺板体积的 35%或更大时，骨强度才会明显降低，而侧向缺陷的骨强度降低程度比内侧缺陷小。此外，皮质窗的近端和骨-水泥界面的最内侧壁是重建失败最脆弱的部位。
