背景在股骨粗隆间骨折的治疗中,对于孤立性大转子骨折和转子间骨折不足的最佳入路仍缺乏共识.患者数量有限,使用磁共振成像准确评估骨折扩展的方法有限,导致治疗策略不明确。本研究旨在利用有限元(FE)分析骨折线处的应力值,并研究它们在不同载荷条件下对股骨粗隆间骨折延伸的影响。假设是在某些条件下发生裂缝延伸,根据科学证据支持手术的需要。方法使用计算机断层扫描(CT)扫描的骨数据使用FEA软件创建股骨近端FE模型。将CT扫描数据转换为医学格式的数字成像和通信,并用于生成FE模型。小梁骨和皮质被划分为四面体元素。该模型由1,592,642个元素和282,530个节点组成。创建了两个模型,即,健康的股骨近端(HF)和股骨转子间不足骨折(FIF)。基于CT值和转换方程分配材料特性。股骨远端受约束。使用动态显式方法进行应力分析。计算股骨近端的VonMises应力。计数超过屈服应力的元素数量,以通过关注断裂线点来预测断裂风险。在这项研究中,在HF和FIF模型之间比较了vonMises应力的分布。考虑了六种荷载组合,即,两个负重条件(3W负荷模拟步行和1/3W触地站立)和三个髋关节屈曲角度(0°,15°,和23°)。结果在3W载荷下,在任何屈曲角度下,HF模型均未观察到明显的应力升高。然而,FIF模型显示后骨折线延伸部位的应力增加.在皮质骨和松质骨中均观察到这种应力引起的元素破坏。对于1/3W的负载条件,在HF和FIF模型中仅观察到最小的应力升高。为了评估对骨折延伸的影响,沿骨折线边缘(大转子和转子间脊的中部)评估了屈服元素的数量。在3W载荷下,HF模型只有一个产生的元素,表明最小的骨折风险。相比之下,FIF模型在不同的屈曲角度:0°(115/16/28)下,在各个区域(总/大转子/轴)表现出明显的屈服元素存在,15°(265/158/23),和23°(446/233/34)。在1/3W的负载条件下,HF和FIF模型都没有显示任何屈服元素,不管外力的方向。结论结果表明,在FIF模型中,骨折线处的应力水平升高,尤其是在行走过程中,表明在弯曲位置骨折延伸的风险较高。然而,在减轻承重的条件下,断裂部位的应力保持在屈服应力范围内,提示骨折延伸的风险相对较低。这些发现对于制定考虑患者遵守负重限制的手术方案具有重要的临床意义。
Background In the treatment of femoral intertrochanteric fractures, there is still a lack of consensus on the optimal approach for isolated greater trochanteric fractures and insufficient intertrochanteric fractures. The limited number of patients and restricted access to accurate assessment of fracture extension using magnetic resonance imaging contribute to the unclear treatment strategy. This study aims to utilize finite element (FE) analysis to analyze stress values at the fracture line and investigate their influence on intertrochanteric fracture extension under different loading conditions. The hypothesis is that fracture extension occurs following certain conditions, supporting the need for surgery based on scientific evidence. Methodology Osseous data from a computed tomography (CT) scan was used to create a proximal femur FE model using FEA software. CT scan data were converted to Digital Imaging and Communications in Medicine format and used to generate the FE model. Trabecular bone and cortex were meshed into tetrahedral elements. The model consisted of 1,592,642 elements and 282,530 nodes. Two models were created, namely, healthy proximal femur (HF) and femoral insufficient intertrochanteric fracture (FIF). Material properties were assigned based on CT values and conversion equations. The distal end of the femur was constrained. Stress analysis using the dynamic explicit approach was performed. Von Mises stresses were calculated for the proximal femur. The number of elements exceeding yield stress was counted to predict fracture risk by focusing on fracture line spots. In this study, the distribution of von Mises stress was compared between the HF and the FIF models. Six loading combinations were considered, namely, two weight-bearing conditions (3 W loading simulating for walking and 1/3 W for touch-down standing) and three hip flexion angles (0°, 15°, and 23°). Results Under 3 W loading, no significant stress elevations were observed in the HF model at any flexion angles. However, the FIF model exhibited increased stress at the site of the posterior fracture line extension. This stress-induced element destruction was observed in both cortical and cancellous bone. For the 1/3 W loading condition, only minimal stress elevation was observed in both HF and FIF models. To assess the influence on fracture extension, the number of yielded elements was evaluated along the fracture line edges (greater trochanter and middle of the intertrochanteric ridge). Under 3 W loading, the HF model had only one yielded element, indicating minimal fracture risk. In contrast, the FIF model exhibited a notable presence of yield elements in various regions (total/greater trochanter/shaft) at different flexion angles: 0° (115/16/28), 15° (265/158/23), and 23° (446/233/34). Under the 1/3 W loading condition, neither the HF nor the FIF models showed any yielding elements, regardless of the direction of external force. Conclusions The results demonstrated elevated stress levels at the fracture line in the FIF model, particularly during walking, indicating a higher risk of fracture extension at the flex position. However, under reduced weight-bearing conditions, the stress at the fracture site remained within the yield stress range, suggesting a relatively low risk of fracture extension. These findings hold significant clinical implications for developing surgical protocols that consider patients\' compliance with weight-bearing restrictions.