Research on key parameters of femoral prosthesis based on static and dynamic analysis

Objective: To assess the influence of stem length and cross section under static and dynamic loading on the stress and fatigue behavior of femoral prosthesis. Method: The round-shaped and drum-shaped femoral prosthesis models were analyzed under both static and dynamic (normal walking) loading conditions with finite element method. The stress on the metallic stem, cement, and adjacent bone as well as the micromotion at the cement-metal interface were analyzed. Safety factors for fatigue life of femoral prothesis were calculated based on the data obtained from the dynamic analysis. Result: Static analysis showed that the drum-shaped cross section could decrease the microdisplacement of stem and the corresponding stress was located on the corner of femoral neck and distal part of femoral prosthesis. The stress on round-shaped stem distributed evenly over most part of stem, and the maximum stress on stem fluctuated with stem length, with a minimum at stem length from 80 to 110mm, and drum-shaped stem with a height 8mm drum generated larger stresses at the distal part of stem than the drum-shaped stem with a height 10mm drum and the round stem. Conclusion:Dynamic and fatigue analysis showed that the drum-shaped stem with a height 10mm drum and a stem with length 90mm had the greatest safety factor, therefore had the longest fatigue life.