It is difficult to explain the difference between a dislocation of an ankle and a fracture.
It is important that the injury be considered a fracture no matter what. It is necessary to apply pressure along the bone margin and ask the victim if he/she feels pain in an upright position. A that point load a weight on the ankle, which causes pain. If the victim is able to take a few steps it is likely that the ankle is just sprained. If the ankle is fractured, the victim will not try to load any weight and will not will be able to take more than 4 steps.
What to do?
- Remove the shoes and check the injury.
- Check CSM (circulation, sensitivity, movement).
- Using RICE procedures. Every minute delay for such a procedure can add an hour to recovery.
Source: Mediserve‘s Pocket Guide to First Aid.