生物可吸收高强度左旋聚丙交酯材料在体内的力学特征

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

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。

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.