Finite Element Analysis Of Contact Trajectory And Mechanical Properties Of Brachial Radial Joint After Artificial Radial Head Prosthesis Replacement

Objective:Finite element method is applied to mechanical analysis that the radial head prosthesis replacement between before and after analyzed the humeroradial joint contact with track changes, stress and contact area changes.Background: It is very complicated that elbow injury result in radial head fracture mechanism. For complex Mason Ⅱ, Ⅲ radial head fractures conduct radial head prosthesis replacement. After radial head prosthesis replacement, whether the humeri lateral condyle contacts with prosthesis are in good condition, whether there is a stress concentration, whether of contact trajectory are consistent before and after the replacement, whether elbow pain is related to the stress concentration after the replacement. In the meantime humeroradial joint contact in the process of elbow motion trajectory, and the contact area change and stress will not only help to understand the mechanism of radial head fractures occurred, but also for the design of the artificial radial head prosthesis provide valuable reference.Method: Chose healthy, young male volunteer’s right elbow joints as experiment object,through the clinical and X-ray eliminate joint disease or deformity. Using high-resolution 64 row dual-source spiral CT scan the right elbow joints, and save DICOM format. Based on the CT scan images of the right elbow joint, application MIMICS software to elbow in addition to the noise, a threshold analysis processing,such as secondary 3-d reconstruction elbows. At last, the obtained data import Hyper Mesh software. Apply the Hyper Mesh software meshing of 3 d model, material properties, establish contact equivalence processing. And establish a humeroradial joint at 0 °, 45 °, 90 °, 120 ° buckling Angle under finite element contact model. And the same time the model boundary restrictions and 50 n physiological load. We establish finite element model of the radial head prosthesis in the same modeling method.Meanwhile simulate replacement process. Through the finite element ANSYS software calculate under different elbow flexion angles between the stresses before and after the of the radial head prosthesis replacement. According to the humeroradial joint contact stress distribution on the surface of the humeroradial joint contact trajectory is deduced.Results: Using finite element modeling method and according to the theory of contact can set up the humeroradial joint finite element contact model and the model is real and effective. By analyzing the mechanical simulation of the flexion and extension of the elbow, what it solved the radial joints between the stress and the stress distribution.According to stress distribution in the joints between the contacts could to know path and contact area changes. In the process of elbow flexion, radial head articular surface and on the surface of the humerus lateral condyle joint contact area at 0 °, the stress distribution in the radial head posterolateral articular surface, located in the most of the side humerus lateral condyle articular surfaces. At 45 ° stress distribution on the surface of the radial head joint bilaterally, its smallest contact area and stress is the largest,11579.60 KPa, distributed in the humerus lateral condyle joint middle position below.At 90 ° and 120 ° of the stress distribution in the center of the radial head on the surface of the joint position, distributed in the humerus lateral condyle joint back below. In elbow from 0 ° to 120 ° of flexion, radial head joint surface rendering within forward from outside to the center of the trends. According to the theory of contact stress and relationship between, yellow to red gradient area is the contact area on the stress distribution. Contact area between humeroradial joint in the process of elbow flexion from large to small change again big trends. The humeroradial joint between stress values changed from small to big and smaller trends. Elbow flexion 45 °, the smallest contact area and stress is the largest, 11579.60 KPa. What the radial head prosthesis of the anatomy before and after radial head prosthesis replacement contact between change and mechanical properties is accordance within the scope of the 90 ° elbow flexion humeroradial joint. The humeroradial joint appear contact trajectory change and stress concentration in the 90 ° ~ 120 °. The outside humerus condyle on contact with anatomical model around the prosthesis sag caused stress concentration. It may be one of the reasons for the elbow pain after elbow joint replacement.Conclusion: The finite element contact model can better analyze and calculate the model contact area changes between joints and the change of stress. Mechanics analysis was carried out on the humeroradial joint which the radial head in elbow stress conduction and stability play an important role. When the radial head are fractures should be reconstruction of radial head, as far as possible to avoid complications after radial head resection. Through the calculation of this model, the results of the analysis should be avoided in elbow flexion 45 ° is large when the violence, or should be protected, in order to avoid causing joint damage or fracture. The radial head prosthesis replacement conforms to the biomechanical properties of the elbow, play an important role of elbow joint stability and function. But in the 90 ° ~ 120 ° when contact with track change and stress concentration, can be further guide the design of prosthesis.