生物吸收材料外消旋聚丙交酯的降解动力学研究

Degradation Kinetics of Bioabsorbable PolyDLlactide(PDLLA)

目的：研究高分子量的外消旋聚丙交酯（ＰＤＬＬＡ）的降解动力。方法：用ＰＤＬＬＡ棒（４ｍｍ×５ｍｍ×３５ｍｍ）于模拟体液和新西兰兔肌肉内降解２４周，定期测量机械强度（三点弯曲和剪切强度）和粘均分子量。体外组观察达２０个月。结果：ＰＤＬＬＡ的分子量和强度半衰期为８～１２周之间（１０周左右），体内降解速度快于体外降解速度。ＰＤＬＬＡ棒的强度衰减与分子量降解具有良好的相关关系。其强度维持可以满足应力小的松质骨内固定。ＰＤＬＬＡ棒于模拟体液中降解２０月后，才完全碎裂。结论：证明ＰＤＬＬＡ为一种具有开发价值的新型吸收性接骨材料。

Objective:To study degradation behaviors of polyDLlactide.Methods:The PDLLA rods(4mm5mm35mm)were immersed in a solution of phosphate buffered saline or implanted into the dorsal muscle of 12 rabbits,and removed in periodical times.Mechanical strength(three point bending strength and shear strength) and viscosity measurement were employed to study the degradation property in vitro and in vivo.And as long as 20 months,the PLA rodsmacroscopic change was studied in the degradation solution.Results:The half time of the viscosityaverage molecular weight of the PDLLA rods was 8 weeks in vivo,and between 812 weeks in vitro.The half time of bending and shear strength was between 812 weeks,also.The degradation in vivo was faster than in vitro.Both the degradation of the mechanical strength retention could be sufficient for the internal fracture fixation of the lowstrain of cancellous bone.Conclusion:For internal fixation of fracture,PDLLA owns fairly large value to develop.