Dynamic Fatigue Behavior of Hip Joint under Patient Specific Loadings

Abstract

In the present work, a finite element model with standard Charnley’s implant of hip joint is considered for investigation under different patient-specific dynamic activities obtained in vivo. The application of forces occurred due to human movement, which ultimately generates dynamic stress over the prosthesis. Anatomical loading constraints are more clinically relevant than ISO standards. The performance of different materials for each suitable gait pattern is analyzed using commercial finite element code. A liner isotropic material Ti-6Al-4V and PMMA material is utilized for an implant and bone cement, respectively. However, cortical and cancellous bone are treated as non-isotropic in nature. Clinically obtained dynamic forces and torque are being used for the present investigation. Additionally, Goodman, Solderberg, Gerber and ASME elliptic fatigue theories were considered to obtain the fatigue life of the implant. The most strenuous activity in terms of stress and strain are, going downstairs followed by going upstairs, walking, standing up and sitting down, which have been found in good agreement with the safety factor for every activity. Additionally, the life expectancy of the implant was a minimum of 23 years under every dynamic motion. The present work exhibits the greater relevance in terms of the life expectancy of implant for the pre-surgical analysis before implanted in vivo.