SIMULATION OF FUNCTIONAL ANKLE TESTING: WHAT A MUSCULOSKELETAL MODEL CAN REVEAL

Ankle injuries are among the most common injuries in sports. Kemler et al. have reported intermediate rates in Dutch children but rising substantially in adolescents (15-24 y). The aim of this study was to investigate the influence of the manually applied external loads on ankle movement during simulated physical examination. Computational simulations of the AnteriorDrawerTest (ADT), TalarTiltTest (TTT) and MedialSutalarGlide (MSG) Test were performed. A computational model was developed in AMS v.6.0.4. (AnyBody Technology A/S, Denmark). The model included 3D representations of tibia, fibula, talus and calcaneus, obtained from CT scans of a specimen. The tibia was fixed in space, with one translational DOF between tibia and fibula in the mediolateral direction. ISB recommendations were followed to construct the tibial and calcaneal reference frames, while the talar reference was aligned with the tibia's. Ankle ligaments were included into the model using anatomical atlases and pictorial essays (Golano et al., 2010). A contact model was defined for the representations of the articular surfaces between adjacent bones. The contact force between the articular surfaces was computed in respect to the penetration volume using the FDK solver within AMS. Anterior force was 80 N anteriorly for ADT simulation, inversion moment was 6 Nm for TTT, and MSG forces were 80 and 150 N at varied contact points. Three ankle integrity scenarios were compared: all ligaments intact (IN), no ATFL and no ATFL + CFL. Foot flexion (DP) was varied from −20–20°. Application point of the ADT and TTT simulations (left) and the selected application points for the MSG simulations (right). Tibia reference frame (blue), talus (green) and calcaneus (red). Displacements for MSG simulations was 0.1-2 mm laterally, coupled to inversion of 0.6-5.8° depending on force application location. For TTT, calcaneal inversion of talus and calcaneus ranged arount 5–10° and increased to over 40° with ruptured ATFL and CFL. Further results to be presented. The proposed model demonstrated biomechanical behavior consistent with clinical observations. These results provide suggestions for the application and interpretation of the physical examinations tests. Such models are useful for interpretation and potential adaptations of such tests for injured ankles of young athletes, whos joint composition is not fully matured.