Stress radiography and stress examination of the talocrural and subtalar joint on helical computed tomography.

The main objective of this study was to compare subtalar inversion stress views using the Brodén view with inversion stress views on helical computed tomography (CT). One of the drawbacks of routine radiography is the imaging of three-dimensional structures in a two-dimensional plane. We investigated whether the use of helical CT would lead to a more objective and clearer measurable method to determine the amount of tilt in the subtalar joint. A group of 15 patients with unilateral chronic instability complaints and clinically suspected subtalar instability was examined. The contralateral asymptomatic foot was used as control. A variable amount of subtalar tilt (range, 4 degrees to 18 degrees) was demonstrated in all cases on stress radiographs, without finding significant difference between the symptomatic and asymptomatic feet. However, contrary to the findings at the talocrural level, subtalar tilt was found in none of the patients using helical CT. Thus, we now doubt that the tilt seen during stress examination using the Brodén view is the true amount of tilt. It may be that the lateral opening, seen on these radiographs, largely results from imaging two planes that have made a translatory and rotary movement relative to each other in an oblique direction. It is concluded that the Brodén stress examination might not be useful for screening patients with subtalar instability. Associated anomalies not visible on the radiographs were detected by helical CT. In four cases, narrowing of the articular cartilage and irregular and hypertrophic bone formation at the middle facet joint of the subtalar joints were found. It is likely that these changes cause disturbance of function of this joint and it is suggested that the subjective complaint of instability with "giving way" is not only caused by hypermobility, but can be caused by other disturbance of normal motion.