While we tend to talk about the ankle as if it were a single joint, it is actually two joints. The portion that we usually mean when we refer to the ankle is called the true ankle joint. It is the coming together of three bones: the fibula of the shin on the outside of the ankle; the tibia, also of the shin, on the inside of the ankle and that talus bone underneath them. It is responsible for the up and down movement of the foot.
The subtalar joint is the second part of the ankle. It is the coming together of the talus above and the calcaneus (heel bone) below. This joint allows the ankle to move from side to side.
These joints, along with the ligaments that hold the bones together absorb all the stress your ankle receives as you walk, run or jump. They carry the weight of your body and help keep you balanced on uneven ground.
When any of these bones are broken, you are said to have an ankle fracture. The most common fracture is to the bony bump on the outside of the ankle, the lateral malleolus. The lateral malleolus is the bottom of the fibula, the smaller lower leg bone. The bump on the inside of your ankle, the medial malleolus, is less commonly fractured.
Ankle fractures can be either:
- Nondisplaced, where the bone cracks but the joint stays in place with your talus between the tibia and the fibula, or
- Displaced, where the broken bones are pulled out of their normal alignment in the joint (dislocated). Fortunately, most ankle fractures occur without a dislocation.
Symptoms of an Ankle Fracture
In comparison to a sprain, where you can usually walk on your ankles, ankle fractures tend to be very painful. Most people with a fractured ankle can't put weight on it. A fractured ankle or significant sprain causes immediate swelling and the ankle cannot be moved. The key difference is that sprains tend to heal in a week or two and the pain diminishes. A fracture will hurt until it is treated.
Causes and Risk Factors of Ankle Fractures
Ankle fractures most often happen when your foot lands an uneven step, floor or playing field, and tilts. If the ankle does not get straightened in time, it can be severely twisted out of position and the bones can fracture.
The peroneal muscles running along the outside of lower leg and across the ankle are responsible for supporting your ankle. If they are weak, your chances of fracturing or spraining an ankle go up.
Diagnosing an Ankle Fracture
Your doctor will generally ask how you hurt your ankle, how it has felt since the injury, and whether you have injured your the ankle before and ask about your physical and athletic goals to help decide the best course of treatment.
Doctors often can diagnose an ankle fracture by pressing around the ankle to see if there are any tender spots, bumps in the bones or swelling. Your doctor may move your ankle up, down, side-to-side and around in a circle to which positions are most painful.
X-rays usually are ordered first to see whether the anklebones have been fractured. X-rays can show cracks in the bones and bone chips on the bone surface. In growing children, sometimes the fracture occurs through the growth plate and is invisible on the X-ray. A magnetic resonance imaging scan (MRI) may be needed to see if there is damage to the cartilage or associated soft tissues, ligaments or tendons. A computed tomography (CT) scan may be needed to get a clear picture of your bones. These may show fractures missed by X-rays.
Treating Ankle Fractures
Treatment options include: