A posterior malleolus fracture is a break on the lower back side of the shin bone. Ankle surgery is often required to fix a posterior malleolus fracture, and recovery may take months.

There were 673,214 ankle fractures treated in emergency rooms in the United States between 2012 and 2016. However, only 1% of ankle fractures are isolated posterior malleolus fractures. These are breaks solely on the lower back side of the shin bone.

Most posterior malleolus fractures occur in addition to other fractures. An isolated posterior malleolus fracture is very rare.

This type of fracture is important to repair as it can cause ankle joint instability that can lead to:

  • partial dislocation of the ankle (subluxation)
  • complete dislocation of the ankle
  • traumatic arthritis

This article takes a closer look at posterior malleolus fractures, including potential causes, treatment options, and recovery.

Illustration showing the anatomy of the ankle and where a posterior malleolus fracture might occurShare on Pinterest
Anatomy of the ankle and where a posterior malleolus fracture might occur. Illustration by Jason Hoffman

The ankle joint is where three bones join: the fibula, tibia, and talus. When people talk about an ankle fracture, they can mean a break in any one or combination of these.

One place where a fracture can take place is the bulbous ends of these bones, which are known as malleoli. This includes the posterior malleolus, which is located on the lower back side of the tibia (otherwise known as the shin bone).

Because of its position, the posterior malleolus is unlikely to be broken on its own. However, if an isolated posterior malleolus break occurs, it’s hard to get it back in the proper position and stabilized for healing.

A trimalleolar fracture is a more common way for a posterior malleolus fracture to appear. This means that the medial and lateral malleolus are also injured. A serious ankle injury, ligaments and tissues may be injured when this occurs, too.

Some potential causes of an ankle fracture include:

  • twisting or rolling an ankle
  • tripping or falling
  • a car accident
  • a sports injury
  • overuse

You may have a posterior malleolus fracture if you have a swollen and painful ankle. The area is often bruised or painful to the touch. Cracking and grinding noises can also indicate that a fracture has occurred.

If your doctor suspects you have an ankle fracture, they may perform a physical exam and suggest an X-ray or CT scan to get a better idea of what bones are injured. An MRI may also be used to evaluate potential ligament or cartilage injury.

Surgery is often necessary to treat a posterior malleolus fracture.

There has been some debate over the years about when surgery on the posterior malleolus is necessary, but many doctors now agree that more should be weighed than just the size or location of the fracture. For example, the stability of the ankle will frequently be considered.

Doctors will typically make an incision on the back of the ankle for this surgery. From this point, they can use screws and plates to secure any fragments.

Many times only the initial surgery is required, and the screws and plates can be left inside the individual permanently. In rare cases, though, an individual may need to have a second surgery later to remove the screws and plates.

Recovery after surgery for a posterior malleolus fracture will look similar to rehabilitation from other types of ankle surgeries.

You can expect that your doctor will immobilize the ankle, and you’ll be asked to refrain from walking on it for about 6 weeks. Crutches, a knee scooter, or a wheelchair can help you to stay somewhat mobile during this time.

After this, physical therapy can help to restore mobility, and weight-bearing exercises may be recommended to help with healing.

It may be close to 6 months after surgery before your ankle is fully healed. However, it can take even longer depending on the amount of repair work necessary.

Recovery may take longer if you smoke or develop an infection. Certain conditions like diabetes can also extend how long healing takes. There may also be an increased risk of:

  • chronic ankle pain
  • traumatic arthritis
  • ankle joint instability
  • decreased range of motion

A posterior malleolus fracture means that there has been a break on the lower back side of the tibia or shin bone. This type of injury is rare in isolation, so it’s likely that if you have a posterior malleolus fracture, you have other fractured bones or torn ligaments in your ankle, too.

A posterior malleolus fracture usually requires surgery to heal properly, so it’s important to notify your doctor if you believe that you have a posterior malleolus fracture. They can use X-rays and CT scans to get a better understanding of the fracture.