Department of Mechanical Engineering, Indian Institute of Engineering Science and Technology, Shibpur, Howrah 711103, West Bengal, India.
Department of Mechanical Engineering, Indian Institute of Engineering Science and Technology, Shibpur, Howrah 711103, West Bengal, India.
Injury. 2024 Oct;55(10):111717. doi: 10.1016/j.injury.2024.111717. Epub 2024 Jul 8.
Several internal fixation devices are available for treating Pauwels type I, II and III femoral neck fractures. The present study compared various fixation implants for all Pauwels fracture types using a CT-based subject-specific finite element model of the femur and determined the most effective implant for each fracture type.
The analysis included four different configurations of cannulated screw models, Femoral Neck System, Dynamic Hip Screw and Dynamic Condylar Screw (with and without anti-rotational screw). Ti-alloy was considered as the implant material. Heterogeneous bone material property was assigned based on CT grey value. Frictional contact was assumed in the contact interfaces. Peak loading corresponding to normal walking and stair-climbing were considered. Equivalent strain in bone, equivalent stress in the implants, femoral head deformation and rotation, micromotion in the contact interfaces, and strain-shielding in bone were evaluated for each implanted model.
Stresses generated in the implants were within the yield limit of the implant material. In Pauwels I and II, the micromotion predicted at the contact regions in all the implanted models was within 100 µm, which is suitable for bone integration. However, in Pauwels III fracture, most of the implanted models other than DHS with AR-screw model exhibited micromotion of more than 150 µm in the contact regions, which is expected to inhibit bone growth.
The DHS with AR-screw implanted model was identified as the most effective in treating Pauwels I and III fractures. However, for Pauwels type II, DCS with an AR-screw implant was deemed superior to the other configurations.
有几种内固定装置可用于治疗Ⅰ型、Ⅱ型和Ⅲ型股骨颈骨折。本研究通过股骨的基于 CT 的个体化有限元模型比较了各种固定植入物治疗所有 Pauwels 骨折类型，并确定了每种骨折类型最有效的植入物。
分析包括四种不同构型的空心螺钉模型、股骨颈系统、动力髋螺钉和动力髁螺钉（带和不带抗旋螺钉）。考虑使用钛合金作为植入物材料。基于 CT 灰度值分配异质骨材料属性。在接触界面假设摩擦接触。考虑了正常行走和爬楼梯对应的峰值载荷。评估了每个植入模型的骨等效应变、植入物等效应力、股骨头变形和旋转、接触界面的微动以及骨的应变屏蔽。
植入物中产生的应力在植入物材料的屈服极限内。在 Pauwels I 和 II 中，所有植入模型在接触区域预测的微动都在 100 µm 以内，这适合骨整合。然而，在 Pauwels III 骨折中，除 DHS 加 AR 螺钉模型外，大多数植入模型在接触区域的微动超过 150 µm，预计会抑制骨生长。
加 AR 螺钉的 DHS 植入模型被确定为治疗 Pauwels I 和 III 骨折最有效的方法。然而，对于 Pauwels II 型，带 AR 螺钉的 DCS 被认为优于其他构型。
