PROTEIN RELEASE KINETICS OF A BIODEGRADABLE IMPLANT FOR FRACTURE NON-UNIONS

Non-union of long bone fractures is often a serious complication of fr acture healing. It is estimated that 100 000 non-unions occur in the U nited States annually and result in the loss of function of the involv ed limb. The present study was performed to develop a microporous poly lactic acid-polyglycolic acid (PLA-PGA) implant for the delivery of bo ne morphogenetic protein (BMP) to sites of fracture nonunions, and to characterize the protein release kinetics of such an implant in vitro. A 50:50 copolymer of PLA-PGA was used to fabricate the implants using a gel formation technique. The implants were subjected to hydrolytic degradation in phosphate-buffered saline at 37 degrees C for up to 72 d. The protein release and the polymer degradation were monitored duri ng this time period. The release kinetics of these implants were studi ed using a model protein, soybean trypsin inhibitor (Tl), as well as B MP. The results indicate that there is a burst release of the proteins in the initial 48 h followed by a lower elution rate. The release of both the proteins followed similar trends. The molecular weight of the polymer decreased at a faster rate compared to its mass.