Enhancing femur’s osteogenic response using a composite nailing

The utilization of an optimized angle-ply composite intramedullary nailing (IN) is proposed to improve the mechanical stimulus to the osteogenic response (MSOR), after the fracture stabilization, of a human femur. An asymptotic homogenization technique is accomplished to convert the carbon fiber-reinforced polymer (CFRP) angle-ply IN in a homogeneous IN. A finite element (FE) model is proposed to simulate a femur bone’s loaded by muscular forces, in association with the homogeneous IN, on a gait loading protocol. The combination of the strain magnitude with the number of daily cycles triggers the modeling and remodeling processes. To properly evaluate the influence of the IN angle-ply, a mathematical function is used to calculate the MSOR on the femur’s periosteum. Also, the maximum strain failure criterion is considered to guarantee that there is no damage in the CFRP angle-ply IN, ensuring that IN is working in a structurally safe condition. The results show an increase of up to 35% in bone’s MSOR for the angle-ply IN [± 30] compared with the traditional stainless-steel (SS) IN, that has been currently used. The utilization of a CFRP angle-ply IN instead of the most usual SS IN follows a modern trend of substituting metallic IN by a composite IN, which can be fabricated in a customized way for each patient. The results showed that the utilization of an optimized composite nail, for the analyzed case, obtained an improvement of MSOR by around 35%, contributing to reducing the strain shielding imposed by the nailing positioned inside a human femur.