In vivo biostability of polysiloxane polyether polyurethanes: resistance to biologic oxidation and stress cracking.

摘要: Polyether polyurethanes are extremely interesting for use in implantable devices. They are, however, susceptible to autoxidative degradation and stress cracking. One approach improving biostability is replace some of the polyether with polysiloxane. Shore 80A 20% (PS-20) 35% (PS-35) polysiloxane were strained 400% elongation implanted rabbits. Twelve weeks implant showed that both significantly more biostable than their polysiloxane-free controls. After 18 months implant, PS-20 developed localized tensile fractures. PS-35 no sign visual damage. Infrared surface analysis does not allow direct evaluation autoxidation because SiOSi stretch peaks mask bands. Secondary indicators suggest possible very slight surfaces, but enough develop cracks. The controls did show substantial infrared evidence autoxidation. Molecular weights long-term explants negligibly lower. In comparison, control suffered molecular weight loss. Positive negative performed as expected. recommended devices do sustain high fixed loads. dramatically its unmodified analogues chronically © 2006 Wiley Periodicals, Inc. J Biomed Mater Res,