A special testing device was developed to simulate the different kinds of injuries and to determine the necessary or originating forces and moments. By means of this testing device it was possible to adjust the following parameters referring to the ankle joint in accordance with the possible positioning in the various kinds of high ski boots—dorsal flexion, pronation or supination, and load, dependent on the skier's weight.
Afterward, the injury mechanism was induced by means of a continuous outer or inner rotation of the fixed lower leg. Starting from the Genetic Classification of ankle joint injuries according to Lauge-Hansen, which describes their origin and pattern, the following problem arose: Is this Genetic Classification of fractures in the ankle joint area also wholly valid in the case of an “arthrodesian” effect in the high ski boot? In order to answer this question, tests were performed on human bone specimen. The load characteristics and the directions of the application of force were determined in preliminary tests in ordef to obtain well-aimed clinical patterns of injuries in fracture tests. For this purpose, photoelastic examinations were carried out by means of photoelastic bone coating and polarized light.
The results of our tests so far are: Torsion of the lower leg relative to the tarsus may occur in the high ski boot even if the boot is optimally fastened; considering the special situation of the high ski boot, the cases of simple eversion and inversion should be added to the classification based on Lauge-Hansen; injuries induced with fixed positions of pronation and supination have proved to be just like those of free movement.