RESUMEN
Objective To design a new type of external fixator for bone fracture and verify its rationality and feasibility. Methods The frame and screw of stainless steel achieved fracture fixation in vitro with a threaded locking structure.At the same time the increasing thickness of body frame, the inclined nail holes and the raised bottoms were designed to greatly enhance the strength and overall stability of body frame.FEM (finite element method),measuring the relative displacement and stress distribution after axial load,was used to verify the rationality of the design.An animal experiment with sheep was used to verify the feasibility of fracture treatment. Results Simulated result of FEM indicated that the biggest relative displacement between the separated bones was 0.04 mm,which was much less than the minimum value 1 mm required for fracture healing.The maximum stresses applied on the frame of the fixator,fixator screw,and bone were 35,26,and 6 MPa, respectively, which was much less than the allowable stress. In the animal experiment, fracture site was fixed firmly after operation and was well cured 3 months later.Conclusion The design of this new device is feasible and it can be used as a new method of fracture treatment.
RESUMEN
0.05).[Conclusion]1.It showes a higher stress dodge in the calcar femorale after using various kinds of prosthesis implantation.After using CFR/PSF of lower elastic modulus as handle,the stress dodge rate is lower in femur,but the interface stress is higher,and this is the main factor and reason for the prosthesis loosening.2.The stress force rule meets the design principle that the stress force decreases gradually in the bone interface from proximal to distal.The stress value in different combination of same prosthesis handle has no significant difference,that showes mechanical factor is not the main standard for selecting prosthesis combination.