基于正交试验接骨螺钉参数的生物相容性评价

Orthopedic screw parameters in the orthogonal test: biocompatibility evaluation

背景:当前骨科螺钉参数研究多集中于力学性能方面,缺少对其生物相容性的评估。目的:探究接骨螺钉材料属性及几何参数对生物相容性的影响规律,探求各因素及水平的最佳组合,为接骨螺钉的设计提供理论参考。方法:针对接骨螺钉5个因素的3个水平进行正交试验方案设计,因素A为螺钉直径(4.5,5.5,6.5 mm),因素B为螺纹牙型(矩形、梯形、三角形),因素C为螺钉螺距(1.75,2.25,2.75 mm),因素D为螺纹深度(0.5,1.0,1.5 mm),因素E为弹性模量(45,110,200 GPa),分别对18组不同螺钉参数下的骨-钉三维模型进行生物力学有限元分析,得出各组试验方案下的应力分布情况及2个试验指标值:皮质骨-螺钉之间的应力传递参数STPα,松质骨-螺钉之间的应力传递参数STPβ。利用权矩阵分析方法对正交试验数据进行分析进而得出影响规律及最佳组合。结果与结论:不同因素的不同水平对于生物相容性影响程度不同,其中螺钉材料属性为最主要影响因素,其次是螺纹牙型、螺距和螺纹直径并且三者影响程度相近,而螺纹深度影响最小。正交试验所得最佳组合方案为大径为6.5 mm、梯形螺纹、螺距为2.75 mm、螺纹深度为0.5 mm、弹性模量为45 GPa的接骨螺钉。

BACKGROUND:Most current studies of orthopedic screw parameters focus on mechanical properties but lack biocompatibility assessment.OBJECTIVE:To investigate the influence of geometric parameters and material properties of orthopedic screws on biomechanical compatibility,explore the optimal combination of various factors and parameterization levels,providing a theoretical reference for the design of orthopedic screws.METHODS:An orthogonal experiment protocol was designed according to the five factors and three parameterization levels of orthopedic screws.Factor A was the screw diameter(4.5,5.5,6.5 mm),factor B was thread profile(rectangular,trapezoidal,triangular),factor C was screw pitch(1.75,2.25,2.75 mm),factor D was the thread depth(0.5,1.0,1.5 mm),and factor E was elastic modulus(45,110,200 GPa).The biomechanical finite element analysis of the three-dimensional bone-nail model under different sets of screw parameters was carried out.Stress distribution and two experimental indicators(the stress transfer parameter STPαbetween the cortical bone and the screw,and the stress transfer parameter STPβbetween the cancellous bone and the screw)under different experimental schemes were obtained.The weighted matrix analysis method was used to analyze the orthogonal experimental data to obtain the influence law and the optimal combination.RESULTS AND CONCLUSION:Different levels of different factors have different degrees of influence on biocompatibility.Among them,the screw material properties are the most important factors,followed by the thread profile,pitch and thread diameter,and the last was the thread depth.The thread profile,pitch,and thread diameter had similar influence on biocompatibility.The optimal combination of the orthogonal experiment was an orthopedic screw with a large diameter of 6.5 mm,a trapezoidal thread,a pitch of 2.75 mm,a thread depth of 0.5 mm,and an elastic modulus of 45 GPa.