The effect of the syndesmotic screw on the extension capacity of the ankle joint

Summary

To investigate whether, when inserting a syndesmotic screw, the foot position effects the range of motion in dorsal extension, 16 osteoligamentous lower-leg preparations were studied. The specimens were placed in a test frame where a constant dorsal extension force could be applied to the foot. The dorsal extension capacity was recorded with a syndesmotic screw inserted by a standardized technique in various plantar flexion positions. The dorsal extension capacity decreased by an average of 0.1° for every degree of increase in plantar flexion when the screw was being inserted. There was a correlation between a large decrease in range of motion and a limited dorsal extension capacity to start with. No correlation could be found between a large decrease in range of motion and a large difference in width between the anterior and posterior edges of the talar trochlea. The results suggest that the foot should be in maximal dorsal extension when a syndesmotic screw is inserted in order to decrease the risk of stiffness.