三叉形股骨膨胀式空心加压螺钉的研制及生物力学分析

背景：传统治疗股骨颈骨折的内固定器械在骨-螺钉界面握持力不足或术后承载负荷过大时,可造成螺钉的松动或拔出,内固定失效率较高。目的：研制三叉形股骨膨胀式空心加压螺钉,并分析其生物力学性能。方法：根据股骨颈骨折的特殊生物力学特性研制的三叉形股骨膨胀式空心加压螺钉,由中空主钉和可拧入主钉内孔道的内栓部分组成,通过内栓旋入后对主钉前部的挤压产生膨胀加压作用。以传统AO空心加压螺钉作为对照组进行生物力学实验,分别进行轴向压缩实验、三点弯曲实验、最大轴向拔出力实验。结果与结论：在300N的轴向外力作用或弯曲外力下,实验组轴向压缩刚度、弯曲刚度高于对照组（P〈0.05）,纵向位移及桡度低于对照组（P〈0.05）。实验组最大轴向拔出力高于对照组（P〈0.05）。表明三叉形膨胀式空心加压螺钉固定牢靠,生物力学性能明显优于普通AO空心螺钉,具有较好的抗轴向压缩能力及抗弯曲、抗旋转能力,在抗拔出性方面更具有普通AO空心螺钉所不具备的优势。

Design and biomechanical analysis of trigeminal form expansion hollow compression screw

BACKGROUND：Traditional fixation device for femoral neck fracture can cause screw loosening,extraction and higher failure rate when fixation device on bone-screw interface with insufficient grasping force or bearing load too large.OBJECTIVE：To develop and evaluate biomechanical characteristics of the trigeminal form expansion hollow compression screw.METHODS：Based on the special biomechanical characteristics of the femoral neck fracture,the trigeminal form expansion hollow compression screw was designed,which was composed of two parts：hollow nail and inside plug which could be screwed into the channel of the hollow nail.Within the bolt screwed through the nail produced pressure effect.Then AO cannulated screw by anti-axial compression was made as control.Axial compression test,three-point bending test and maximal axial pullout strength test were detected respectively.RESULTS AND CONCLUSION：Under 300 N axial or bending external force,axial compression stiffness and bending stiffness in the experimental group were higher than those of the control group （P〈0.05）,but axial displacement and radial degree in the experimental group were lower than those of the control group （P〈0.05）.The maximal axial pullout strength of the experimental group was higher than that of the control group （P〈0.05）.It is indicated that trigeminal form expansive hollow compression screw is significantly superior to AO cannulated screw in fixation firmly and biomechanical properties.Trigeminal form expansive hollow compression screw has good performance in anti-axial compression,anti-bend,anti-torsion and anti-pullout which is the advantage that AO cannulated screw does not have.