The unstable ankle mortise--functional ankle varus.
A new etiology of lateral ankle instability is described. The concept of triplane motion at the ankle joint differs with previous descriptions of ankle joint movement. Triplane movement about the ankle joint creates varus position during plantarflexion, and must be understood when evaluating ankle instability. Functional ankle varus can be assessed and treated appropriately with proper knowledge of its existence.
D000843:Ankle Joint / Q000503:physiopathology*; D001696:Biomechanical Phenomena; D006801:Humans; D007593:Joint Instability / Q000503:physiopathology*; D009119:Muscle Contraction; D013977:Tibia / Q000503:physiopathology