Stress in the human ankle joint: a brief review.

The articular bones of the ankle joint are subjected to stress along their vertical axis by the resultant force Rt [13]. On this compressive stress is superimposed bending resulting from tensile forces exerted by the collateral ligaments. The loading by tensile forces is greatest in the lateral areas of the joint, especially at the fibular malleolus. The bony elements of the ankle joint are adapted to this specific mode of stress by the distribution of osseous material in the subchondral bone and by cancellous architecture. Results from photoelastic model tests correspond to the morphological findings if models are subjected to stress by both compressive forces and tensile forces. Zones with high fringe orders of isochromatics in the model correspond to areas with high density of the osseous tissue in equidensity pictures, and the trajectorial pattern in Plexiglas models mirrors the alignment of compressive and tensile cancellous trabeculae.