The investigation of osteoconduction and in vitro degradation characteristics in synthetic absorbable biomaterials and/or their ceramic composites.

摘要

Bioabsorbable polymers have received significant attention in recent years for their potential as materials used in orthopedic surgical implants. Currently there is not an ideal biomaterial that provides a combination of controlled degradation, sufficient mechanical properties, and is replaced and absorbed by the body.; This thesis involves the study of several absorbable polymers and/or their ceramic composites. These materials were fabricated into implants to be used in an animal study to determine their level of osteoconductivity (ability to support bone growth). Initially the materials were analyzed for change in molecular weight as a result of processing (twin-screw extrusion, injection molding, and sterilization), content of fillers employed (ash test), and by scanning electron microscopy (SEM). Additionally, the materials were subject to in-vitro conditioning to determine the effects of aging on mass loss, dimensional stability, and mechanical properties.; All materials decreased in molecular weight as a result of processing to varying degrees. The materials containing ceramic fillers contained the attempted concentrations. The copolymer of 85% D,L-lactide, and 15% glycolide exhibited the most significant mass loss at 16 weeks in-vitro. Materials containing ceramic fillers increased in diameter compared to those not containing fillers during in-vitro aging. Although samples containing ceramic fillers displayed higher values of stiffness at time 0, samples containing Poly (L-lactide) demonstrated the greatest strength retention during in-vitro aging. At twelve weeks in-vivo, the only material to show evidence of osteoconduction was a copolymer of 85% D,L-lactide, and 15% glycolide.