Cha Yonghan, Park Sunghoon, Jung Chang-Ho, Kim Jin-Woo, Yoo Jun-Il, Kim Jung-Taek, Jeon Yongho, Han Kyeong Jin
Department of Orthopedic Surgery, Daejeon Eulji Medical Center, Eulji University School of Medicine, Daejeon, Korea.
Department of Radiology, Ajou University Medical Center, Ajou University School of Medicine, Suwon, Korea.
Clin Orthop Surg. 2025 Apr;17(2):204-215. doi: 10.4055/cios24194. Epub 2024 Dec 6.
This study explores effective fixation methods for Pauwel type III femoral neck fractures by evaluating the biomechanical benefits of adding a screw to the Femoral Neck System (FNS).
Computed tomography (CT) scans of an 82-year-old female patient with an intertrochanteric fracture were used to establish a finite element femur model with heterogeneous material properties. Finite element models of Pauwel type III fractures were created with and without an additional screw. The central and inferior trajectories of the FNS bolt were examined separately and combined with an additional screw for virtual fixation. Walking and stair-climbing loads were applied.
With the addition of a screw, both peak maximum and minimum principal strains consistently stayed comparable or decreased in models with both central and inferior bolt trajectories, while the volume of elements with principal strain exceeding 1% decreased by more than half. The peak von Mises stress observed in the implants ranged from 215.7 to 359.3 MPa, remaining below the titanium alloy's yield strength of 800 MPa. For normal walking, the addition of a screw to the central bolt trajectory model decreased the fracture gap by 50.6% and reduced sliding distance by 8.6%. For the inferior bolt trajectory, the gap was reduced by 57.9% and sliding distance by 25.0%. Under stair-climbing conditions, these improvements were also evident; the central trajectory model saw a halved fracture gap and a 7.9% decrease in sliding distance, while the inferior trajectory model experienced a 55.7% gap reduction and a 27.2% decrease in sliding distance. The additional screw increased the area ratio of the fracture site experiencing interfragmentary compression 34%-39%, while the additional screw alleviated peak interfragmentary compression by 12%-18% under both normal walking and stair-climbing conditions.
The addition of a screw reduced the fracture gap, sliding distance, and peak interfragmentary compression, while increasing the area ratio of interfragmentary compression under both walking and stair-climbing loads, regardless of the FNS bolt trajectory, suggesting a better mechanical environment for fracture healing.
本研究通过评估在股骨颈系统（FNS）中增加一枚螺钉的生物力学优势，探索 Pauwel III 型股骨颈骨折的有效固定方法。
利用一名 82 岁转子间骨折女性患者的计算机断层扫描（CT）图像，建立具有异质材料特性的有限元股骨模型。分别创建有无额外螺钉的 Pauwel III 型骨折有限元模型。分别检查 FNS 螺钉的中央和下方轨迹，并与额外螺钉组合进行虚拟固定。施加行走和爬楼梯载荷。
增加一枚螺钉后，在中央和下方螺钉轨迹模型中，最大和最小主应变峰值均持续保持相当或降低，而主应变超过 1%的单元体积减少了一半以上。植入物中观察到的 von Mises 应力峰值在 215.7 至 359.3 MPa 之间，仍低于钛合金的屈服强度 800 MPa。对于正常行走，在中央螺钉轨迹模型中增加一枚螺钉可使骨折间隙减少 50.6%，滑动距离减少 8.6%。对于下方螺钉轨迹，间隙减少 57.9%，滑动距离减少 25.0%。在爬楼梯条件下，这些改善也很明显；中央轨迹模型的骨折间隙减半，滑动距离减少 7.9%，而下方轨迹模型的间隙减少 55.7%，滑动距离减少 27.2%。额外的螺钉使骨折部位承受骨折间压缩的面积比增加了 34% - 39%，而在正常行走和爬楼梯条件下，额外的螺钉使骨折间压缩峰值减轻了 12% - 18%。
无论 FNS 螺钉轨迹如何，增加一枚螺钉均可减少骨折间隙、滑动距离和骨折间压缩峰值，同时在行走和爬楼梯载荷下增加骨折间压缩的面积比，这表明为骨折愈合提供了更好的力学环境。
