The interference screw made of bioabsorbable polymers has been widely used in bone tissue engineering. Among the various ranges of polymer materials, the composite of polylactic glycolic acid (PLGA) and β-tricalcium phosphate (β-TCP) exerts high performance of biocompatibility and bioabsorption for the knee fixation and reconstruction surgery. The purpose of this research is to first investigate the influence of screw thread geometry on the mechanical properties of the biocomposites interference screw made of PLGA/β-TCP composite. Three biocomposite interference screws with different thread designs were compared in terms of the maximum insertion torque and pullout force via numerical analysis. It was found that the thread design with modified pitch failed to improve the ease of insertion into the bone tunnel and resistance of removal. Although the modified thread angle type enhanced the pull-out strength, the higher insertion torque and strain energy density (SED) exerted on the bone made it was easy to break during the insertion process and enlarge the bone tunnel. Then, based on the optimal design of the screw, in-vitro degradation experiment over 26 weeks was conducted to investigate the degradation kinetics and evaluate the mechanical properties of the PLGA/β-TCP interference screw. The in vitro degradation analysis revealed that the molecular weight residual rate and degradation time presented a linear negative correlation within 0 to 16 weeks and the degradation rate was significantly accelerated after 16 weeks. However, it didn't exhibit any differences in mass loss with the degradation time, which indicated that the material can still keep the shape in half a year. In other words, the interference screw made of PLGA/β-TCP composite can meet the requirements of clinical use and has a certain degree of safety.

由生物可吸收聚合物制成的干涉螺钉已广泛用于骨组织工程中。在各种高分子材料中，聚乳酸乙醇酸（PLGA）和β-磷酸三钙（β-TCP）的复合材料在膝关节固定和重建手术中具有高性能的生物相容性和生物吸收性。本研究的目的是首先研究螺纹几何形状对PLGA /β-TCP复合材料制成的生物复合材料干涉螺钉的机械性能的影响。通过数值分析比较了三种不同螺纹设计的生物复合材料干涉螺钉的最大插入扭矩和拔出力。已经发现具有改变的螺距的螺纹设计不能提高插入骨隧道的容易性和去除阻力。尽管改进的螺纹角型提高了拉出强度，但施加在骨骼上的插入扭矩和应变能密度（SED）更高，使得在插入过程中很容易断裂，并扩大了骨通道。然后，基于螺杆的最佳设计，进行了26周的体外降解实验，以研究降解动力学并评估PLGA /β-TCP干涉螺杆的机械性能。体外降解分析表明，分子量残留率和降解时间在0至16周内呈线性负相关，且降解速度在16周后明显加快。但是，它的质量损失与降解时间没有任何差异，这表明该材料仍可以保持半年的形状。