摘要
用特殊的加热压缩方法固态压缩法 (solid statecompression ,SC)加工左旋聚丙交酯 (poly L lac tide ,PLLA) ,获得高强度SC PLLA(弯曲强度 2 5 0Mpa,剪切强度 190Mpa)。将SC PLLA棒 (3.2mm× 30mm) ,置于PBS液或植入兔的皮下和股骨内 ,定期观察粘均分子量、结晶度、扫描电镜 (SEM )形态和机械性能 (弯曲强度和剪切强度 ) ,研究该材料的降解特征和强度特性 ,以评价其作为矫形外科骨固定装置材料的价值。结果表明 ,各组分子量在前 12周下降迅速 ,其后缓慢下降 ,至 72周时 ,各组分子量降解 98%以上 ;结晶度则与此相反 ,12周内上升迅速 ,36周达最大。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。SC PLLA降解 2 4周后 ,各组的弯曲强度仍维持在 180MPa以上 ,剪切强度在 75MPa以上 ,都大于皮质骨强度 ,提示材料的强度维持时间满足一般的骨内固定要求。因此SC
A special heating compression process, solid-state compression (SC) method, was developed to process poly-L-lactide (PLLA) to improve its mechanical strength. The SC-PLLA possesses higher strength (bending strength and shear strength were 250Mpa and 190Mpa, respectively) than those of human cortical bone. The SC-PLLA rods (3.2mm × 30mm) were immerged in PBS solution and implanted in to rabbits' subcutanous tissue and bone for 72 weeks. By investigating the viscous average molecular weight, crystallinity, micromorphology, and the mechanical strength (bending and shear strength), the degradation properties and mechanical strength retention of SC-PLLA were studied to evaluate its potential as orthopedic bone fixation material. The molecular weight decreased rapidly after the first 12 weeks following implantation, then it decreased slowly down. At 72 weeks post-degradation, the molecular weights decreased more than 98% in various groups. But the degree of crystallinity showed a reversed change with the molecular weight decrease, almost reaching its maximums after 12 weeks. In the scanning electron micrography of the SC-PLLA, numerous orderly fibers longitudinal to the axis of the rod were formed in the inner part of the rods, but were destroyed later, and pores then appeared. After 24 weeks post-degradation, the bending and shear strength of the SC-PLLA rods retained 180 Mpa and 75Mpa, respectively. These were still higher than those of human cortical bone, which means that the time of strength retention of the material is also fit for bone fixation. Thus, SC-PLLA is a promising bioabsorbable osteosynthetic material.
出处
《中国生物医学工程学报》
EI
CAS
CSCD
北大核心
2003年第3期283-288,共6页
Chinese Journal of Biomedical Engineering
基金
广东省卫生厅重点基金资助项目
关键词
生物可吸收
左旋聚丙交酯
内固定
骨折
Bending strength
Bone
Compaction
Degradation
Heating
Molecular weight
Organic polymers
Shear strength
