Effect of the AirStirrup in Controlling Ankle Inversion Stress

Subtalar ankle inversion with and without AirStirrup application was evaluated using high speed cinematographic techniques and a specially designed platform that inverts the ankle 35 O. Eighteen subjects aged 19 to 35 and with no history of ankle injury participated in the study. Two trials were filmed for each subject. Although the same ankle was tested in each trial, AirStirrups were applied to both ankles in one trial and to neither in the other trial so subjects could not anticipate the inversion stress. Points marked on the knee (posterior), the Achilles tendon, and the distal calcaneous were digitized. These data were smoothed employing cubic splines and used to calculate the maximum angular displacement (inversion) at the subtalar joint in each of the conditions tested. A t-test revealed a significantly (p c 0.001) larger inversion angle for the ankle not braced with fhe AirStirrup. J Orthop Sports Phys Ther 1987;9(5):190-193.