It is well known that the research of co-linear and oblique crashes have progressed since NHTSA had reported that the large number of fatalities occurred in crashes involving poor structural engagement between the vehicle and its collision partner in 2009. Moreover, a new frontal crash dummy, THOR, is being developed for which a variety of new risk functions has been proposed. Especially, an ankle injury is being considered for a new injury assessment. In this study, the main purpose is to evaluate the ankle injury risk functions based on the accidental analysis and the human finite element (FE) simulation based on NHTSA co-linear and oblique research tests. First, the accident frequency of the ankle injury in US frontal crash accidents was compared with various ankle injury risk functions. Second, the ankle injury mechanism was investigated by conducting human FE simulations focusing on the ankle behavior in order to clarify the effect of the tibia compression on the ankle injury. It was found that the ankle injury risk functions without tibia compression effect estimated higher risk than the actual accident. On the other hand, it was identified that the talus and fibula damage could change drastically by the eversion and inversion of the ankle with/without tibia compression by human FE simulation. Therefore, the ankle injury risk function proposed has better correlation with the accidental data with can consider the rotational direction and the tibia axial compression.