<p>Prior studies related to the finite element analysis (FEA) of human lower leg bones under static load have not considered bone marrow and fibula mentioning that the bone marrow does not contribute to the bone strength and the fibula has no role in load support. However, the response of these two needs to be explored under dynamic load. Here, we have carried out FEA of the lower leg bone models with and without bone marrow, and with and without fibula under different types of dynamic loads that a knee joint encounters while performing various activities. In the FEA, bone marrow is considered as a linear viscoelastic solid, whereas functionally graded orthotropic material properties are assigned to the bone material surrounding the bone marrow. FE results reflect that the bone models with marrow help in stress relaxation during and after a particular activity is over, whereas the cyclic stresses remain intact even after the activity is over in the models without bone marrow. Moreover, compared to a tibia model with bone marrow, a tibia–fibula model with bone marrow not only reduces the magnitude of stresses (up to 7%) but also relaxes the stresses faster (half duration) after an activity ends. Thus, we find that tibia and fibula are analogous to a paired system having two dampers in the form of bone marrow that contribute primarily in relaxing the cyclic nature of stresses developed while performing dynamic activities. Since, such an analysis has not been attempted in past, the present study is a novel attempt towards the FEA of human lower leg bones under dynamic loads for observing the effect of bone marrow and fibula.</p>