Lateral Malleolus Fracture: Anatomy, Diagnosis, and Treatment

Lateral Malleolus Fractures are the most common type of ankle fracture, accounting for approximately 55% of all ankle fractures. These fractures are often caused by traumatic events such as falls or trips, but can also result from overuse injuries or poor biomechanics.

In this article, we will discuss the anatomy of the ankle joint, the various types of Lateral Malleolus Fractures, as well as the conservative and surgical treatment options available for this condition.

Anatomy of the Ankle Joint

The ankle joint is comprised of three bones: the tibia, the fibula, and the talus. The tibia and fibula are long bones in the lower leg, with the tibia being the larger of the two.

The fibula runs parallel to the tibia, on the outside of the leg. The talus is a small bone that sits on top of the heel bone, and it forms the lower part of the ankle joint.

The lateral malleolus is a bony prominence on the fibula that sits on the outside of the ankle joint. It acts as a weight-bearing structure, absorbing approximately 10% of the weight in standing. Due to its position and role in weight-bearing, it is more commonly injured than the medial malleolus.

Lateral Malleolus Fracture Incidence Rates

A study of 9767 patients with ankle fractures over a period of 9 years found that lateral malleolus fractures are the most common type of ankle fracture, accounting for 55% of all ankle fractures. The incidence rate of this injury appears to be similar between genders, but studies have found that it is more prevalent in females as they age.

Lateral Malleolus Fracture Symptoms

Symptoms of a Lateral Malleolus Fracture include swelling and bruising over the lateral ankle, pain on weight-bearing, walking or hopping, pain when walking on uneven surfaces, and a protruding bone or malaligned foot in severe cases. However, it is important to note that some patients may not experience significant pain when walking due to low levels of body weight going through the lateral malleolus.

Types of Lateral Malleolus Fractures

There are several types of Lateral Malleolus Fractures that can occur, ranging from stable to unstable fractures. Here are some of the most common types of Lateral Malleolus Fractures:

Weber B Fracture

This type of fracture occurs at the ankle level of the lateral malleolus and may extend up the fibula. It can involve the ligaments attaching to the fibula and can be stable or unstable. Weber B fractures are generally stable fractures that can be managed conservatively with immobilisation and physical therapy.

Displaced Fracture

This is when a gap appears in the bone at the site of the fracture and these often require surgical repair

Epiphyseal Fracture

This is a type of fracture involving the growth plate and is common in children

Flake or Avulsion Fracture

This is where the ligament is pulled off the bone and in doing so it can pull some flakes or fragments of the bone off with it.

Lateral Malleolus Fracture with syndesmotic disruption

The syndesmosis attached the tibia and fibula together, this becomes torn or compromised with this type of fracture.


Lateral Malleolus Fractures can be caused by a variety of factors, including:

  • Poor biomechanics
  • Poor footwear
  • Ankle sprains
  • Falls
  • Trips (61%)
  • Repetitive overload through impact activities such as running
  • Trauma such as impact to the ankle joint

Diagnosis & Radiology

A consultation with a Physical Therapist, Podiatrist, or Sports Medicine Doctor is recommended if you have any of the symptoms of a Lateral Malleolus Fracture.

A clinical interview of your symptoms alongside a clinical examination can often be sufficient to achieve a diagnosis for your therapist. A clinical examination will often involve a hop test and tap test.

This is usually followed by imaging to rule out other conditions and to confirm the diagnosis. An x-ray is the primary imaging model, but if this returns, as usual, a referral for an MRI or Ct Scan may be required. A study of 123 patients with lateral and mortise x-ray views are 95% accurate in diagnosing ankle fractures as anteroposterior, lateral and mortise views.

Lateral Malleolus Fracture Conservative Treatment

A stable Lateral Malleolus Fracture is usually managed with 4-6 weeks in a walker boot. Historically a cast was used, but the walker boot allows for greater function and equivalent healing response.

During this period, Physical Therapy can begin to maintain the mobility of the surrounding tissues, such as the Calf, Peroneal, and Posterior Tibialis muscles. Upon removal of the boot, rehabilitation can last for 4-6 weeks. This involves strengthening and mobility exercises of the foot and ankle. Graded exposure to impact activities and return to play protocols if you wish to return to sport. Rehabilitation exercises are similar to that of a sprained ankle.

Taping and/or an ankle brace may be used when returning to activities that require a change of support, especially for those with unstable ankles. Surgery is not usually required for a stable fracture.

Lateral Malleolus Fracture Surgery

For unstable Lateral Malleolus Fractures or a malunion, surgery may be required. This is often an ORIF involving metalwork such as a plate stabilising the broken bone. You may require the use of a walker boot after surgery, and rehabilitation with a Physical Therapist can last for 6-12 weeks.

Post-operative complications include nerve damage if a nerve is cut during the procedure, but these surgeries are generally very successful overall.


In conclusion, Lateral Malleolus Fractures are a common type of ankle fracture that can be caused by a variety of factors. Early diagnosis and treatment can lead to a successful outcome, and conservative treatment is often sufficient for stable fractures.

For unstable fractures, surgery may be required, but with proper rehabilitation, most patients can expect a full recovery. If you suspect you have a Lateral Malleolus Fracture, seek medical attention promptly to avoid further damage and ensure the best possible outcome.

Wynne Lee, MD

Dr. Wynne Lee is a physician at Massachusetts General Hospital (MGH), where she provides primary care.

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