生物可吸收高强度左旋聚丙交酯材料在体内的力学特征

目的观察生物可吸收固态压缩法增强的、高强度左旋聚丙交酯poly-L-lactide,PLLA材料在体内的力学变化特征,评价其作为骨固定装置材料的价值. 方法用特殊的加热压缩方法-固态压缩法(solid-state compressionSC)加工左旋聚丙交酯,得SC-PLLA试棒(3.2mm×30mm),植入兔的皮下和股骨内,在长达48周的降解时间里,观察材料的力学性能(弯曲强度和剪切强度)和扫描电镜(SEM)下的微观形态. 结果植入24周后,各组SC-PLLA在体内的力学强度均可维持在弯曲强度180Mpa以上,剪切强度75Mpa以上,它们都大于皮质骨强度.剪切强度的下降比弯曲强度快.SEM见SC-PLLA降解前内部有大量排列整齐的纵向纤维,并随降解而破坏并出现孔隙. 结论固态压缩法可获得高初始强度和维持强度的PLLA,满足一般的骨内固定要求.SC-PLLA是一种有前途的生物可吸收接骨材料.

THE IN VIVO MECHANICAL PROPERTIES OF BIOABSORBABLE HIGH STRENGTH POLY-L-LACTIDE MATERIAL

Objective to investigate the mechanical properties of the bioabsorbable solid-state compression reinforced high strength poly-L-lactide (SC-PLLA) material in vivo Methods SC-PLLA rods (3.2mm×30mm) were made by a special heating compression - the solid-state compression process. The morphological properties and the mechanical strengths (bending and shear strength) of the rods were investigated succesivly after the rods were implanted in rabbits subcutanously and in bone. Results Tuenty-four weeks after implantation the bending and shear strength of SC PLLA rods remained above 180 Mpa and 75Mpa respectively. They were higher than the strength of human cortical bone. The shear strength decreased faster than the bending strength. Under the scanning electron microscope numerous ordered fibers could be seen longitudinal to the axis of the rod inside the SC-PLLA material. After implantation the fibers could be degraded with time and the material become porotic. Conclusion Solid-compression process could obtain high initial and retention strength PLLA which could fit for the general bone internal fixation. SC-PLLA is a promising bioabsorbable osteosynthetic material.