Static and dynamic roentgenographic analysis of ankle stability in braced and nonbraced stable and functionally unstable ankles.

Patients suffering from functional ankle instability were selected based on a structured interview. Talar tilt was measured using supine ankle stress roentgenographs and standing talar tilt was measured using erect ankle stress roentgenographs. A digital roentgenocinematographic analysis of a 50 degrees ankle sprain simulation was performed to measure dynamic talar tilt and inversion distance between two video images (inversion speed). A significant decrease in pathologic supine talar tilt in unstable ankles was found in the braced compared with the nonbraced situation (talar tilt = 13.1 degrees versus 4.8 degrees with brace). The talar tilt with the brace after activity was still significantly lower than the initial value without the brace. The standing talar tilt of unstable ankles was shown to be significantly lower with the orthosis than without (standing talar tilt = 16.6 degrees versus 12.0 degrees with brace). Roentgenocinematographic evaluation of ankle sprain simulation showed that the mean dynamic talar tilt during simulated sprain decreased significantly in the braced ankles compared with the nonbraced ankles (dynamic talar tilt = 9.8 degrees versus 6.4 degrees braced). A significant decrease in the digital measurement of inversion distance (from 110.6 pixels to 92.4 pixels) was observed in the total sample of 39 ankles during the initial high-speed phase of the simulated sprain. The brace significantly slows down the inversion speed.