The present paper is focused on the problems of clinical diagnostics of the functional disturbances in the locomotor apparatus as exemplified by the injuries to the ankle joint. The results of analysis of the entire range of up-to-date diagnostic tools for the purpose suggest the necessity of revision of obsolete methodological principles still adopted in forensic medicine as regards the problem being condidered. It is proposed based on the recent progress achieved by the specialists in traumatology, orthopedics, medico-social expertise, and the related areas that a forensic medical expert should not confine oneself to the consideration of the sole criterion, such as "the range of articular movements", for the estimation of the severity of harm to health in the patients presenting with a joint injury.