Li Xishan, Zhou Xiang, Yang Jie, Böker Kai Oliver, Schilling Arndt F, Lehmann Wolfgang
Department of Trauma Surgery, Orthopedics and Plastic Surgery, University Medical Center Göttingen, Göttingen, Germany.
Department of Articular and Traumatic Orthopedic Surgery, Fourth People's Hospital of Guiyang, Guiyang, Guizhou, China.
Front Bioeng Biotechnol. 2025 Mar 6;13:1441026. doi: 10.3389/fbioe.2025.1441026. eCollection 2025.
Femoral neck fractures are prevalent in orthopedic injuries, often leading to complications such as nonunion and osteonecrosis of the femoral head (ONFH). Studies indicate that after healing and removal of internal fixation devices, some patients develop ONFH, while others experience osteosclerosis around the screw holes due to prolonged fixation, increasing ONFH risk. Despite such observations, biomechanical studies on this phenomenon are limited. This study assesses the risk of femoral head collapse post-internal fixation device removal and investigates the biomechanical effects of bone grafting at screw removal sites.
Using CT data, femoral anatomy was reconstructed. For control, the femoral head's collapse area was identified. Experimental models, divided into those with and without bone grafts in screw holes, incorporated three fixation techniques, namely, triple cannulated screws (3CS), dynamic hip screws with cannulated screws (DHS+CS), and the femoral neck system (FNS), further subclassified into normal and sclerotic screw-hole models. Stress distribution, stress values, stress index, and strain range were assessed.
In both models, DHS+CS showed the highest stress in the overall model, while 3CS had the highest stress in the collapse area. The 3CS configuration also resulted in the largest strain range, which was observed in the central pillar of normal screw-hole models and the lateral pillar of sclerotic screw-hole models. The bone graft models exhibited lower peak, average stress, and strain values than the normal and sclerotic screw-hole models.
The FNS screw hole demonstrates a relatively lower mechanical risk of femoral head collapse. In contrast, sclerotic screw holes increase this risk, while bone grafting may improve the biomechanical behavior after fixation removal, potentially reducing the likelihood of femoral head collapse.
股骨颈骨折在骨科损伤中很常见，常导致诸如骨不连和股骨头坏死（ONFH）等并发症。研究表明，在愈合并取出内固定装置后，一些患者会发生股骨头坏死，而另一些患者由于固定时间延长，在螺钉孔周围出现骨质硬化，增加了股骨头坏死的风险。尽管有这些观察结果，但关于这一现象的生物力学研究却很有限。本研究评估了取出内固定装置后股骨头塌陷的风险，并研究了在螺钉取出部位进行植骨的生物力学效果。
利用CT数据重建股骨解剖结构。作为对照，确定股骨头的塌陷区域。实验模型分为螺钉孔有植骨和无植骨两组，并采用三种固定技术，即三枚空心螺钉（3CS）、带空心螺钉的动力髋螺钉（DHS+CS）和股骨颈系统（FNS），进一步细分为正常和硬化螺钉孔模型。评估应力分布、应力值、应力指数和应变范围。
在两种模型中，DHS+CS在整个模型中显示出最高应力，而3CS在塌陷区域应力最高。3CS构型还导致了最大的应变范围，在正常螺钉孔模型的中央支柱和硬化螺钉孔模型的外侧支柱中观察到。植骨模型的峰值、平均应力和应变值均低于正常和硬化螺钉孔模型。
FNS螺钉孔显示出相对较低的股骨头塌陷机械风险。相比之下，硬化螺钉孔会增加这种风险，而植骨可能会改善取出固定后骨的生物力学行为，潜在地降低股骨头塌陷的可能性。
