Evaluation of poly(lactic-co-glycolic acid) plate and screw system for bone fixation

In this study, we investigated the efficacy and safety of the recently developed modifiable bioabsorbable plates and screws, which are made of PLGA [poly(lactic-co-glycolic acids)]. An in vitro extract test and a mammalian erythrocyte micronucleus test revealed that neither cytotoxicity nor genotoxicity was observed with the plates and screws tested in this study. An in vivo mandible fracture model in rabbit was introduced to evaluate the in vivo efficacy and of the PLGA-based plates and screws. At 4, 6, 8, and 10 weeks after implantation, tissue specimens were taken from the implanted sites of the rabbits and a histologic analysis was performed for each of the specimens. After 4 weeks, the plate was covered by connective tissues and severe chronic active inflammation in soft tissue was observed. After 6 weeks, the inflammation decreased and some of the specimens exhibited new bone formation around the periosteum. After 8 and 10 weeks, new bone formation was observed with all samples, where almost no severe inflammation was involved, implying the healing of the fracture. Given these, it can be suggested that the biodegradable plate and screw system that we evaluated in this study is effective for treatment of mandible fracture, one of the regions under a high load-bearing condition. The adjustment process and the long-term follow-up study are in progress for clinical application of the plate and screw system introduced in this study.