Design and biomechanical study of a novel adjustable hemipelvic prosthesis

A pelvic endoprosthesis is commonly used in orthopedic surgeries to reconstruct the pelvis after internal hemipelvectomy. This study presents the detailed design of a novel type I+II+III adjustable hemipelvic prosthesis based on the geometrical features of massive human pelvises. Finite element analysis is conducted to estimate the biomechanical performance of the newly designed adjustable hemipelvic prosthesis. Detailed numerical models of the natural and reconstructed pelvises including related soft tissues are developed. Hip contact forces during normal walking, which is one of the most frequent dynamic activities in daily living, are imposed on the pelvis. Results show that the peak stress observed in the reconstructed pelvis model is still within a low and elastic range below the yielding strength of the cortical bone and Ti6Al4V. No significant difference of the stress transferring route, displacement distributions and principal stress vectors is observed between the reconstructed and natural pelvises. The results indicate that the load transferring function of the partially resected pelvis is able to be reliably recovered by the adjustable hemipelvic prosthesis. The principal stress vectors in both pelvis models predict that bone absorption may not apparently occur in the long run. Long-term biomechanical performance of this newly designed prosthesis may be stability.