When a bone breaks or cracks, the injury is called a fracture. In the ankle, three different bones can be fractured:
The tibia — This is the larger of the two bones in the lower leg. The tibia's lower end flares out, forming a hard, bony knob, called the medial malleolus, which you can feel at the inside of your ankle.
The fibula — This is the thinner of the two bones of the lower leg. Its lower end forms a hard, bony knob, called the lateral malleolus, which you can feel at the outside of your ankle.
The talus — This is a wedge-shaped bone that is located deep inside the ankle, braced between the heel bone and the ends of the tibia and fibula. The talus supports the lower ends of the tibia and fibula, and it forms a solid base for the normal range of ankle movements.
Although there are many ways to fracture an ankle bone, the most common injuries involve a sharp twist of the ankle or a direct impact that fractures at least one of the bony knobs in the ankle.
Ankle fractures are common injuries among people of all ages, interests and lifestyles. People involved in a wide range of athletic activities, including ballet dancers, snowboarders, basketball players and skydivers, are at high risk of ankle fractures because of the physical demands placed on their ankles. Ankle fractures also occur during slips on icy pavement, falls from a high place, or direct impacts to the ankle during a car crash or motorcycle accident. High-impact ankle injuries are especially dangerous if the bone pokes through the skin and is exposed to the air. The open wound allows bacteria to contaminate the broken bone, and greatly increases the risk of infection.