Abstract:

BACKGROUND: An ideal fracture fixation system should strong fix bone fracture at early time and prevent stress shelter effect-induced local osteoporosis. Degradable internal fixation material provides theoretical basis for preparing this fixation system.
OBJECTIVE: To investigate the result and effect of the changeable rigidity plate system composed of degradable poly-lactic-acid gasket and titanium alloy for the fixation of middle tibia fracture of rabbits.
METHODS: Totally 64 New Zealand rabbits were divided into the experimental and control groups randomly. The tibia shaft fracture models were prepared by wire saw. The experimental groups were fixed with changeable rigidity plate systems which were made of self-restraint macromoleculer poly-lactic-acid gasket and 4-hole Tc4 plate. The control group was fixed with 4-hole Tc4 plate only. The bone fracture healing was evaluated by general observation, X-ray film, histological and biomechanic examination at 2, 4, 8 and 12 weeks after operation.
RESULRS AND CONCLUSION: General observation and X-ray films showed that fracture contraposition and the bone healed well in both groups. The histological examination demonstrated that compared with the control group, osteotylus around the fracture was more thick and dense, marrow cavity cross earlier in the experimental group. The biomechanic examination found that there was no significant in maximum bending strength in two groups at 8 weeks, but the experimental group showed superior to the control group at 12 weeks. All these results prove that the complexity system with the changeable degrational gasket is a reliable method for the fixation of the tibia fracture, which is benefit for the heeling of the bone than single plate. This experiment provides an experimental foundation for its further using in clinic.