Lateral Malleolus Fracture Symptoms and Treatment

A lateral malleolus fracture is a break in the bone on the outside of your ankle joint. The lateral malleolus is part of the fibula, the smaller of two bones of the lower leg that carries around 10% of your body weight.

Lateral malleolus fractures are the most common type of ankle fracture and one that can occur when you take a wrong step and twist or roll your ankle. Most are stable ankle fractures, meaning that the ankle joint remains aligned and able to move normally. These types of fractures don't require surgery.

This article describes the symptoms of a lateral malleolus fracture, including how it is diagnosed and treated.

What Are the Symptoms of a Lateral Malleolus Fracture?

A lateral malleolus fracture involves the large bump on the outer side of your ankle, called the lateral malleolus bone. The fracture is frequently caused by tripping, falling from a height, or twisting or rolling your ankle while walking or running. An impact during a car crash can also cause an ankle fracture.

Lateral malleolus fractures are characterized by the following signs and symptoms:

• Immediate severe pain
• Swelling of the ankle
• Bruising
• Tenderness to the touch
• Inability to bear weight on the injured ankle
• Ankle deformity
• Numbness and coolness in the injured foot

The pain and swelling can spread to other parts of the foot or up toward your knee.

In addition to the fracture itself, there may be pain and swelling on the inside of your ankle. This may be a sign of an injury called a bimalleolar equivalent fracture.

How Is a Lateral Malleolus Fracture Diagnosed?

A lateral malleolus fracture is usually not too serious, but your healthcare provider will likely want to order imaging tests to check for signs of an unstable fracture. A plain film X-ray is usually all that is needed to confirm the diagnosis.

If the injury is severe and/or there is a risk of a soft tissue injury, a computed tomography (CT) scan or magnetic resonance imaging (MRI) scan may be ordered. They both offer different benefits:

• CT scans are comprised of multiple X-ray images and provide a more detailed visualization of the injury, particularly if there is a compound fracture.
• MRIs are non-radioactive imaging studies that are better able to detect soft tissue injuries like torn ligaments or ruptured tendons.

The good news is that most isolated lateral malleolus fractures are stable. Even so, it is important to see a specialist (typically an orthopedist or orthopedic surgeon) who can characterize the fracture and ensure that the right treatment is delivered.

How Is a Lateral Malleolus Fracture Treated?

A lateral malleolus fracture will not heal on its own and will require some form of treatment even if the fracture is stable. 

For a stable lateral malleolus fracture, the treatment will mainly involve managing symptoms and giving your bones plenty of time to heal.

This typically includes:

• Rest and immobilization: You would need to avoid placing any weight on your ankle until ample healing has occurred. Usually, a week or two with crutches is recommended.
• Ice application: To ease pain and swelling, an ice pack or cold compress can placed on the ankle for 15 to 20 minutes several times a day.
• Elevation: Lying down with your ankle elevated above your heart not only reduces swelling but also eases throbbing pain.
• Medications: Over-the-counter nonsteroidal anti-inflammatory medications (NSAIDs) like Advil (ibuprofen) and Aleve (naproxen) can help control swelling and pain.
• Ankle supports: These may involve everything from high-top shoes and hiking boots to air casts, ankle braces, walking boots, and walking casts.

When Is Surgery Needed?

You likely won't need surgery for a stable lateral malleolus fracture. That's because non-surgical treatments have proven just as effective with a far lower risk of complications.

Surgery places you at risk of infection and other postoperative complications like chronic edema (caused by the buildup of fluid in the ankle). If metal implants are used to repair a broken bone, a second surgery may be needed to remove them.

This doesn't mean that all lateral malleolus fractures are treated with rest. If an unstable fracture is left untreated and doesn't heal correctly, it can lead to joint disfigurement, chronic pain, and ankle arthritis.

In cases like this, surgery may be needed.

If ORIF is needed, the fracture will usually heal within four to six weeks. The first couple of weeks would involve an ankle splint and elevation of the foot for around 90% of the day. After that, you can replace the splint with a removable boot. When X-rays show ample healing, you can start weight-bearing exercises under medical supervision.

Even so, surgery is relatively uncommon with lateral malleolus fractures, and some experts question whether ORIF should be the standard of care for all displaced ankle fractures.

Summary

Lateral malleolus fractures involve the bump of bone on the outside of your ankle. They can happen when you take an awkward step and roll or twist your ankle. Most are stable fractures in which the broken bone fragments remain aligned.

Surgery usually isn't required with an isolated lateral malleolus fracture. Instead, rest, ice application, elevation, anti-inflammatory drugs, and ankle support should be enough for the ankle to heal correctly. In severe cases, open reduction internal fixation (ORIF) surgery may be needed.