[A new procedure for measuring displacement of the anterior ankle joint in the lateral projection]

Different methods are recommended for exploration of stress-radiographs of the ankle joint in lateral projection. After considering the geometric-mathematical propositions a new schedule is shown, which combines simple handling with tolerable error level and regards individual bone size. An index is derived from measurements of the tibia and the talus according to certain conditions. The limits for normal, borderline and pathological indices were statistically determined by measurement of 50 lateral stress-radiographs of uninjured ankle sprains. In comparison with the common measuring of an posterior tibio-talar distance better results were found with a higher score of discrimination for the new method. Additionally the new procedure allows exploration of radiographs which do not fulfill the demands to an exact lateral projection of the ankle sprain.