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Broken Ankle

All About Ankle Fractures

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Updated June 02, 2014

ankle fracture

Ankle fracture shown with plates and screws to align and fix the bone.

Jonathan Cluett, M.D.

Ankle fractures are common injuries to the bones around the ankle joint. There are many types of ankle fractures, and treatments vary significantly depending on the location and severity of the injury. Understanding what to do about a broken ankle requires some information about how these injuries occur.

The ankle is a complex joint that forms where three bones come together. The bones of the lower leg, the tibia and the fibula, are above the joint, and the talus is below the joint. When a doctor talks about an ankle fracture, he or she is usually talking about a broken bone of the tibia or fibula.

The tibia, also called the shin bone, is the larger, weight-bearing bone of the lower leg. Of the weight transferred through the leg, about 90% is carried by the tibia. The fibula is the smaller bone on the outside of the leg. It only carries about 10% of your body weight.

Both the tibia and the fibula wrap around the talus to form the ankle joint. The bony prominences at the ankle are called the medial malleolus (the end of the tibia) and the lateral malleolus (the end of the fibula). The ends of these bones form a cup-shape that the talus bone sits within. The most important aspect of ankle fracture treatment is understanding how the talus moves in relation to the ends of the tibia and fibula. Fractures of the ankle are either stable (they movement of the talus is unchanged) or unstable (the talus does not move in a normal manner). This means that the joint is not held in a symmetric position--when the ankle fracture is unstable, more invasive treatment is needed.

The Broken Ankle

When a broken ankle occurs, the injury may be to the end of the tibia (the medial malleolus) or to the fibula (the lateral malleolus), or both. Determining how to proceed with treatment depends on where the injury has occurred. There are many types of ankle fractures, here are the most common:
  • Lateral Malleolus Fractures (fibula only):
    Fractures of the fibula alone are the most common type of ankle fracture. Most fibular fractures can be treated without surgery, but it is important to ensure the ankle joint remains stable. This means that even though there is a break in the bone, the ankle joint still functions normally. If the ankle joint is unstable, then surgery is likely to be recommended. One clue to look for to determine if the fibula fracture may require surgery, is the distance of the fracture to the end of the bone. Fibula fractures within 4 cm of the end of the bone are generally safe to treat nonsurgically, as long as there is no injury on the inner side of the ankle (see below).
  • Medial Malleolus Fractures (tibia only):
    Medial malleolus fractures are relatively uncommon. In general, a displaced (out of position) medial malleolus fracture is treated with surgery.
  • Bimalleolar Ankle Fractures (both tibia and fibula):
    Bimallelolar ankle fractures occur when there is injury to both the inner and the outer side of the ankle. These inuries always result in an unstable ankle joint, and in most active patients, surgery will be recommended. One important point is that sometimes an injury called a bimalleolar-equivalent fracture can occur--this means there is only a fracture of the fibula, but also a tear of the ligaments on the inner side of the ankle. This leads to instability of the ankle joint, just as if the inner side were fractured, and therefore requires surgery.
  • Posterior Malleolus Fracture (tibia only):
    Also a rare injury in isolation, fractures of the posterior malleolus are generally found in association with bimalleolar ankle fractures--in which case the injury is called a trimalleolar ankle fracture.

Symptoms of a Broken Ankle

Common symptoms of an ankle fracture include:
  • Pain to touch
  • Swelling
  • Bruising
  • Inability to walk on the leg
  • Deformity around the ankle
There are clinical criteria used to differentiate ankle fractures from ankle sprains. These guidelines, called the Ottawa criteria help to determine if x-rays should be done in people who have ankle pain.

 

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