[Compensatory movements of the fibula necessitated by the wedge shape of the trochlea tali].

The lateral articular facet of the talus (Facies malleolaris lateralis) is slanting and irregularly shaped; therefore, the fibula shows compensative motions in transverse, sagittal, vertical and rotational directions when the ankle joint is moved. There are contradictory statements concerning the course of this compensative rotation, because the fibula shows individually different reactions. The fibula is not rotated during dorsiflexion in nearly 25% of legs; approximately one half of the remaining fibulae is rotated outward, the other half inward. The matter of fact is not surprising, when the shape of the lateral articular facet is inspected exactly: it resembles a flat saddle, the anterior part of which is screw-shaped. The fibula rotates outward during dorsiflexion, if the furrow of this screw-shaped area increases forward; it rotates inward, if the furrow diminishes forward; and it does not rotate at all, if the furrow is constant.