Dynamic fibular function: a new concept.

Fibular function has long been a point of controversy in the literature. Until recently the fibula's role during gait has been thought of as entirely static. A review of the literature reveals an important dynamic function for the fibula in maintaining ankle mortise stability during weight bearing. Roentgenographic and anatomical studies confirm the hypothesis of progressive distal fibular descent. A taut interosseous membrane and deepened mortise result when be flexors of the foot contract during stance phase. Congenital deformities of the ankle may stem from aberration in the dynamic role of the fibula. Stress fractures and problems resulting from impaired distal migration and synostosis formation are interpreted as disorders of the dynamic role of the fibula.