Acquired flatfoot secondary to tibialis posterior dysfunction: biomechanical aspects.

The biomechanical implications of the normally-functioning tibialis posterior muscle and tendon unit, pathomechanics of its dysfunction, and its diagnosis are presented. The interaction of the tibialis posterior tendon with the rearfoot ligamentous system is discussed. An anatomic consideration of the glenoidal ligaments of the talonavicular joint new to the English literature is presented. A plan for staging the disease of tibialis posterior dysfunction and classifying its etiology is considered to be a prerequisite for proper treatment.