Stress radiography of the talocrural and subtalar joints.

The object of this investigation was to determine a possible subtalar component in a group of 33 patients with chronic ankle instability. A group of 10 subjects without ankle/foot symptoms acted as controls. A standardized radiographic assessment of talar and simultaneous subtalar tilt was made. A hinge device to stress the joints and a specific subtalar stress view (Brodén view) were used under fluoroscopic control. Radiographs were made with the feet: (1) in neutral position, (2) after inversion with moderate force until the point of fair restraint (step 1), and (3) after inverting with more force as far as the conditions would allow (step 2). An increase of talar tilt between step 1 and step 2 was only found in feet that were symptomatic. This suggests that this increase is only possible when lateral ligaments are damaged. Further research is necessary to determine whether this finding can serve as a parameter to discriminate between physiological and abnormal talar tilt. A wide range of subtalar motion was found in both symptomatic and asymptomatic feet. With the present method, practically all subtalar joints showed some loss of congruity and medial shift of the calcaneus in relation to the talus. This could not be correlated with ankle instability at the talocrural joint. The consequence of the use of different subtalar stress methods has so far received little attention and is discussed.