[Compensatory and stabilizing motions of the fibula]

There are two reasons why the fibula shows longitudinal motions. During dorsiflexion the push of the wedge-shaped trochlea tali causes an upward fibular motion; on the other hand, during weight bearing the contraction of the leg muscles effects a downward fibular motion. The specific level of the fibula results from these two correlating forces. While the upward fibular migration is a passive compensative movement, the downward fibular migration is an active stabilizing movement.