| 초록 |
PLLA is quite useful because its degradation occurs with simple hydrolysis of the ester bonds in an aqueous environment, and the degradation products (carbon dioxide and water ) are metabolized by the organism, so that there is no need for subcequent surgery to remove the implant devices. Ideal materials for interial osteosynthesis should have enough initials rigidity to stabilizea bone for 6-12 weeks; moreover, once the bone has had time to heal, the mechanical stability should gradually decrease as the osteosynthesis increases, leading to a gradual transferof load to the healing bone. The purpose of this study is to investigate the in vitro and in vivo degradation of PLLA rod and plate and in vivo histological response of PLLA screw due to the site of implantation. PLLA rod and plate were manufactured by vacuum compression molding and solid-state extrusion technique. Rod with diameter of 3.5 mm and plate with width of 8 mm and thickness of 1 mm were prepared for in vitro. PLLA rod and plate were immersed in a solution of phosphate buffer solution(pH7.0 37℃±0.5℃). PLLA screw for in vivo was machined out from extruded PLLA rods. PLLA screws were implanted at femur of dogs. The in vitro and in vivo degradation of PLLA were discussed by measurement of DSC, GPC, Instron, X-ray, H&E staining.
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