超高分子量聚DL-乳酸降解过程中的超微结构改变

Ultrastructure Characteristics of Super-high Molecular Weight Poly-DL-lactic Acid During Degradation in vitro

目的 :观察超高分子量聚DL_乳酸 (PDLLA)骨折内固定系统在下颌骨骨折内固定时的降解特性。方法 :建立犬下颌骨骨折的实验动物模型 ,采用国产超高分子量PDLLA骨折内固定系统固定下颌骨骨折 ,通过扫描电子显微镜观察术前及术后 1、3、6月可吸收接骨板在降解过程中超微结构的变化。结果 :术前PDLLA材料的表面较为粗糙 ,但表面无明显的孔洞 ;术后 1月 ,材料表面出现龟裂纹 ,为较浅的沟槽 ;术后 3月 ,材料表面深在沟槽明显增多 ;术后 6月 ,材料表面变为完全凹凸不平的堆积物。结论 :PDLLA降解时首先在表面和浅层 ,术后 3月已逐渐深入内部 ,此时其力学强度也明显下降 ,但骨折愈合已基本完成 ,内固定系统开始崩解、吸收 ,从而避免了金属接骨板存在不利于骨折愈合的应力遮当效应。

Objective:The aim of this experiment was to study the character of degradation of super_high molecular weight poly_DL_lactic acid (PDLLA) internal fracture_fixing system.Methods: The fracture mandible of dogs was fixed with super_high molecular weight PDLLA internal fracture_fixing system. In 1, 3, 6, 12 months after the operation, the materials were taken out from dogs, and the palates were observed using the scanning electron microscopy.Results: The surface of super_high molecular weight PDLLA was coarse. In 1 month after the operation, there were much chaps and grains on the surface of PDLLA. In 3 months after the operation, there were much deeper grooves. In 6 months after the operation, only some scraggly accumulation was seen.Conclusion: Super_high molecular weight PDLLA can degrade on the surface in the beginning, and then the material begins to degrade deeply. The speed of degradation matches with the speed of fracture healing. It will help to avoid stress_protecting effect.\;