Blinded prediction of custom-made pelvic implant failure using patient-specific finite element modeling

Additively manufactured, custom-made implants used for reconstruction are a promising treatment following tumor resection. However, failure rates due to mechanical factors remain high when used in the pelvis for even state-of-the-art prosthesis designs. In a collaborative effort between a clinical and an engineering research team, this study evaluated whether patient-specific biomechanical modeling could predict, in a blinded fashion, the mode and location of a clinically-observed mechanical failure. Multiple failure criteria were considered including the risk of bone fracture due to overloading or stress shielding and prosthesis fracture due to overloading or fatigue. The blinded predictions indicated that the risk of fatigue failure in the pubic screws were eight times higher than the most critical ilium screw and two times higher than the most critical cancellous screw. Simulation of stress-shielding during walking matched evidence of osteolysis in the ilium and pubis. Incorporating patient-specific modeling into the custom implant design process may lead to improved durability.