[Establishment and comparative analysis of femoral biomechanical equivalent model]

The human femur is in a relatively complex mechanical environment, subject to the combined effects of multiple factors such as mechanical loads from movement and weight-bearing, as well as changes in the body fluid environment in daily life. In in vitro testing cases of the femur (e.g., testing of distal femoral fractures), changes in load conditions usually significantly affect the mechanical properties of the overall structure. However, there is currently no systematic evaluation standard for in vitro mechanical performance testing of the femur. Therefore, this paper established four human femur models (model A~model D) constructed based on computed tomography (CT) under different load environments, as well as two artificially synthesized femur models (the finite-element model and the experimental model) under the same load environment. Among them, for the human femur models, model A was configured to apply hip joint contact forces together with all muscle forces to approximate the real in vivo mechanical environment, model B was applied with hip joint contact force and abductor muscle force, model C was only applied with hip joint contact force, and model D was subjected to an equivalent resultant force. For the artificially synthesized femur models, both the finite-element model and the experimental model were applied with the same equivalent resultant force as model D. Comparative analyses revealed that model D exhibited femoral head displacement and stress-strain distributions similar to Model A, indicating its suitability as an equivalent in vitro test model. Further comparison between the finite-element and experimental synthetic femur models yielded consistent mechanical responses, thereby validating the equivalent model. In summary, it is hoped that the findings of this study will provide a reference for establishing a systematic, tiered preclinical evaluation system for hip prostheses/implants in the future.