Experiment Study And Numerical Simulation Of Biodegradable AZ31 Magnesium Alloy Bone Plate Fixing Femoral Fracture

Currently stainless steel and titanium are frequently used as fracture fixation repair materials, but the elastic modulus of them is much larger than human bone. Applying magnesium alloys to repair fracture has the advantage that the effect of stress shielding in the later period of bone healing reduces and the patients can escape from the pain of the second surgery. Magnesium alloys AZ31 with good comprehensive performance is selected to design and produce bone plates and bone screws. Magnesium alloy degradation experiments are designed to study the degradation rule of magnesium alloy under different mechanical environments. Electrical measurement experiments and numerical simulations of using both magnesium alloy and titanium to fix femoral middle fracture were conducted to study the mechanical property difference of the two materials. At last, the numerical simulation of magnesium alloy ten holes LC-DCP plate was as the application of magnesium alloys. The main contents are as follows.(1)The research situation of medical magnesium alloys and bone biomechanics is introduced, and the necessity of magnesium alloy research is put forward, at the same time the research ideas and theoretical support are provided.(2)Degradation experiment of magnesium alloy screws is designed to study the degradation rule of magnesium alloy screws in different liquid pressure; Degradation experiment of broken fresh bones fixed by magnesium alloy bone plate and bone screws is designed to study the degradation rule of magnesium alloy in different axial load. The results showed that the mechanical environmental impact the rate of degradation of magnesium alloy.(3)Electrical measurement experiments of fixing femur middle fracture by titanium alloy and magnesium alloy are designed to study the mechanical properties of the two materials. Artificial bone and corpse bone were selected as objects of study, and differences in mechanical properties of the two materials were studied in various stages of bone healing.The results showed that with the gradual healing of the fracture, the stress of bone plate gradually decreased while the stress of femur gradually increased. Femoral side generally withstand compressive strain, the plate side is generally subjected to tensile strain, and magnesium alloy and titanium alloy materials have similar mechanical properties.(4)Numerical simulation of both magnesium alloy and titanium alloy materials contrasted with electrical measurement was conducted to analysis and compare the stress distribution rule of femur middle fracture system. The numerical simulation results werecompared with electrical measurement results, and the mechanical properties of the two materials during bone healing would be be summarized. The results show that the maximum stress of magnesium alloy group is larger than that of titanium group in femoral shaft section and callus section, and the maximum stress of magnesium alloy group is smaller than that of titanium group in bone plate section and bone screws section. The law of numerical simulation is similar with that of electrical measurement experiments.(5)In the case of femoral middle fracture, mechanical properties of magnesium alloy ten holes LC-DCP plate were studied during bone healing by numerical simulation. The maximum equivalent stress of bone plate and bone screws decreased while fracture gradually healed, and the maximum equivalent stress of bone screws is larger than that of bone plate.