Differential Mechanical and Biological Contributions to Bone Mass Distribution—Insights from a Computational Model of the Human Femur

Bone density distribution in the human femur is significantly influenced by mechanical forces that drive bone remodeling in response to physical demands. This study aims to assess how effectively mechanical factors alone explain femoral bone mass distribution and to identify areas where additional, non-mechanical influences may be required. We used a computational bone remodeling model to compare outcomes under two initial conditions: a uniform density distribution and one derived from tomographic imaging. Both conditions experienced identical mechanical loading, with the remodeling process simulated via finite element methods. Results demonstrated that mechanical loading substantially contributes to shaping bone density, but certain structural aspects, notably incomplete cortical bone formation in simulations starting from uniform density, suggest the involvement of other factors. The model also highlighted specific regions susceptible to bone loss under disuse scenarios, such as prolonged inactivity or microgravity. Our findings emphasize the need to incorporate non-mechanical factors and realistic initial conditions into computational models to enhance their applicability for personalized medical analyses.