Objective：To observe the changing of biomechanical features during the degradation course of poly-D,L-lactic acid （PDLLA） rods in vivo and in vitro and to evaluate its value as an internal fixation material. Metho...Objective：To observe the changing of biomechanical features during the degradation course of poly-D,L-lactic acid （PDLLA） rods in vivo and in vitro and to evaluate its value as an internal fixation material. Methods ：PDLLA rods were emerged into PBS simultaneous body fluid with constant temperature of 37℃ and the rods were embedded into muscle tissue of 20 rabbits for degradation in vitro and in vivo . The rods were taken out in 2, 4, 6, 8 and 12 weeks. Biomechanical features of bending, shearing and axial compression strength, rigidity and elastic modulus were observed during the degradation course. Statistical method was used to test the changes of biomechanical parameters. Results： （1）There was similar changes of bending, compressive, shearing strength and bending, compressive and shearing rigidity of the PDLLA rods between in vivo and in vitro. （2）Bending, compressive, shearing strength decreased 33%, 18 % and 43 % respectively within the first stage of the degradation, and after 6 weeks of degradation, they decreased slowly. （3）Elastic modulus, bending, compressive and shearing rigidity.decreased sharply during the 6 weeks of degradation, with a drop of 22%, 39% and 30% respectively, and after 8 weeks, they decreased slowly. Even after 12 weeks of degradation, the strength of the rods was still higher than that of sponge bone. Conclusion： During the degradation of the material, the strength and rigidity of PDLLA rods can meet the need of fracture fixation of cancellous bones.展开更多
Aim:This animal study aims to examine the efficacy and safety of poly-D,L-lactic acid(PDLLA)microspheres as subdermal fillers.Methods:Thirty 2-week-old male Sprague Dawley rats were used as test animals,and 0.5 mL fil...Aim:This animal study aims to examine the efficacy and safety of poly-D,L-lactic acid(PDLLA)microspheres as subdermal fillers.Methods:Thirty 2-week-old male Sprague Dawley rats were used as test animals,and 0.5 mL filler solutions were injected into the subdermal tissues on their backs.Groups of five rats were randomly selected and sacrificed for examination on the 2nd,4th,8th,12th,16th,and 20th weeks after injection.Clinical and histological examinations were performed via the hematoxyline-eosin and immunohistochemical(IHC)staining of injected sites after collecting the injected masses.The body weights of the rats were measured,and the presence of filler substance in other organs was determined.Results:Injected volumes were stable from the 2nd to the 20th week after injection,and no abnormalities were observed around the injection sites.The injected substance did not migrate to the surrounding tissues.In IHC staining experiments,myofibroblasts were observed from the 2nd week,and collagen was detected from the 4th week.Myofibroblast was observed in the spaces between and inside the microspheres in the 8th week after injection,whereas type I collagen was found between and inside the microspheres at 8th and 12th weeks,respectively.Conclusion:The animal experiments confirm the efficacy and safety of injectable PDLLA as a subdermal filler.展开更多
文摘Objective：To observe the changing of biomechanical features during the degradation course of poly-D,L-lactic acid （PDLLA） rods in vivo and in vitro and to evaluate its value as an internal fixation material. Methods ：PDLLA rods were emerged into PBS simultaneous body fluid with constant temperature of 37℃ and the rods were embedded into muscle tissue of 20 rabbits for degradation in vitro and in vivo . The rods were taken out in 2, 4, 6, 8 and 12 weeks. Biomechanical features of bending, shearing and axial compression strength, rigidity and elastic modulus were observed during the degradation course. Statistical method was used to test the changes of biomechanical parameters. Results： （1）There was similar changes of bending, compressive, shearing strength and bending, compressive and shearing rigidity of the PDLLA rods between in vivo and in vitro. （2）Bending, compressive, shearing strength decreased 33%, 18 % and 43 % respectively within the first stage of the degradation, and after 6 weeks of degradation, they decreased slowly. （3）Elastic modulus, bending, compressive and shearing rigidity.decreased sharply during the 6 weeks of degradation, with a drop of 22%, 39% and 30% respectively, and after 8 weeks, they decreased slowly. Even after 12 weeks of degradation, the strength of the rods was still higher than that of sponge bone. Conclusion： During the degradation of the material, the strength and rigidity of PDLLA rods can meet the need of fracture fixation of cancellous bones.
基金This work was supported by Regen Biotech,Inc.,Seoul,South Korea.
文摘Aim:This animal study aims to examine the efficacy and safety of poly-D,L-lactic acid(PDLLA)microspheres as subdermal fillers.Methods:Thirty 2-week-old male Sprague Dawley rats were used as test animals,and 0.5 mL filler solutions were injected into the subdermal tissues on their backs.Groups of five rats were randomly selected and sacrificed for examination on the 2nd,4th,8th,12th,16th,and 20th weeks after injection.Clinical and histological examinations were performed via the hematoxyline-eosin and immunohistochemical(IHC)staining of injected sites after collecting the injected masses.The body weights of the rats were measured,and the presence of filler substance in other organs was determined.Results:Injected volumes were stable from the 2nd to the 20th week after injection,and no abnormalities were observed around the injection sites.The injected substance did not migrate to the surrounding tissues.In IHC staining experiments,myofibroblasts were observed from the 2nd week,and collagen was detected from the 4th week.Myofibroblast was observed in the spaces between and inside the microspheres in the 8th week after injection,whereas type I collagen was found between and inside the microspheres at 8th and 12th weeks,respectively.Conclusion:The animal experiments confirm the efficacy and safety of injectable PDLLA as a subdermal filler.
