Radiographic comparison of plain films in second- and third-degree ankle sprains.

A literature search failed to demonstrate any investigations of the plain films of the ankle to determine whether there were any measurable differences in the ankle mortise, which would differentiate between a second and a third degree ankle sprain, thus obviating the need for stress views. In this study, the authors independently measured the distances between the talus and tibia at eight predetermined sites on the lateral and mortise views. This was done blindly so that neither author knew which cases were second- or third-degree ankle sprains. Only definite third-degree ankle sprains, as defined by a positive anterior drawer sign and/or a positive inversion stress test result on clinical evaluation, were included. The authors found there was severe interobserver variability. The authors thus feel that there is no clinically significant measurement on plain films of the ankle that can be used to differentiate accurately between second and third degree ankle sprains, and current reliance on clinical findings and subsequent stress x-ray films is appropriate and must remain the non-operative standard for evaluation of this problem.