Finite element analysis on stress distributions during novel semi-hip prosthesis assembly / 医用生物力学

ABSTRACT

Objective To simulate the stress generated by contact with the femur during the assembly of novel semi-hip prosthesis, and discuss the operating limits and adaptive prosthesis profile in clinic. Methods CT scans were conducted on the proximal end of the femur in a male volunteer of 60 years old as a physical model. By transferring the CT data to finite element modeling software, the physical model was simplified, meshed, materialized and assembled with the model of prosthesis to establish the three-dimensional finite element model. Surface to surface contact relationship between the femur and the prosthesis was also constructed by utilizing contact elements. Relative sliding distance and stress distribution were solved while simulating the process of assembling the prosthesis. Results Additional stress was generated on the sudden change area of the contact surface when the prosthesis was seated. The greatest contact pressure came from the changing section of the ridge of the prothesis, and the maximum assembly stress and sliding distance range increased nonlinearly along with the pushing distance. The increase rate of additional stress was enhanced significantly while Δz≥0.5 mm. Conclusions Compared with the prosthesis without ridge, the prosthesis with ridge can be easily seated and obtain mechanical stabilization. However, the relevant clinical operating limits should be obeyed to avoid generating excessive additional stress during the implantation of prosthesis, which may cause treatment failure due to the damage in bone cortex.