Comparison of Methods Simulating the Ankle Sprain Mechanism:Inversion Drop Test and Landing on a Slanted Surface

The purposes of this study were to investigate the kinematics of two ankle brace testing protocols. They were drop landing on a slanted surface and the inversion drop test. Difference in kinematics and ground reaction forces of drop landing wearing an ankle brace on flat and lateral slant surfaces were also investigated. Eleven healthy subjects performed five trials in each of six dynamic movement conditions. They were an ankle inversion drop test on the inversion platform, drop landing from 0.45 m onto slant surface, and drop landing from 0.45 m onto flat surface with and without an ankle brace. A 7-camera motion analysis system was used to obtain the threedimensional kinematics. In addition, a force platform was used to measure the ground reaction forces (GRF) during drop landing. A 2 × 2 (brace × movement) repeated measures ANOVA was used to evaluate selected variables for inversion drop test and landing on slant surface (p < 0.05). In addition, the differences between landing on the flat and slant surfaces were examined using a 2 × 2 (brace × surface) repeated measures ANOVA. The results showed that the slant surface landing resulted in significantly earlier maximum inversion angle occurrence. Significantly higher maximum eversion and inversion velocities were also found in the slant surface landing compared to the inversion drop. In the comparison of landing on the slant surface and flat surfaces, the results showed that slant surface landing led to smaller 1^stand 2^ndpeak vertical and horizontal GRFs, greater maximum inversion and its range of motion (ROM), and smaller dorsiflexion ROM. The results suggest that the slant surface landing simulate ankle sprain mechanism better than the inversion drop test. Subjects adopted a softer landing strategy when landing onto the flat surface and a stiffer strategy when landing onto the slanted surface.