biomer and Foreign-Body-Reaction

A series of novel polyurethane elastomers based on methylenediphenyl diisocyanate, 1,4-butanediol and the macrodiols, poly(hexamethylene oxide), poly(octamethylene oxide), and poly(decamethylene oxide) were implanted subcutaneously in sheep for periods of 3 and 6 months. The specimens that were subjected to 3 months of implantation were strained to 250% of their resting length, while those implanted for 6 months had no applied external strain. SEM examination of the explanted specimens revealed that the novel materials displayed resistance to environmental stress cracking. Proprietary materials, Pellethane 2363-80A, Biomer and Tecoflex EG-80A, which had been implanted under identical conditions, showed evidence of significant stress cracking. The extent of stress cracking in the 3-month strained experiment was similar to that from the 6-month unstrained experiment. Stress cracking was also observed in Pellethane 2363-55D, when implanted for 6 months (unstrained). Neither changes in molecular weight nor in tensile properties provided a clear indication of early susceptibility to degradation by environmental stress cracking.

Topics: Animals; Biocompatible Materials; Butylene Glycols; Equipment Failure; Foreign-Body Reaction; Glycols; Hardness; Male; Microscopy, Electron, Scanning; Molecular Weight; Polymers; Polyurethanes; Prostheses and Implants; Sheep; Stress, Mechanical; Surface Properties; Tensile Strength