5 Types of Medial Malleolus Ankle Fractures

A broken ankle may need surgery

When you break the inner bone of your ankle, it is called a medial malleolus ankle fracture. The medial malleolus is an anatomical region of the tibia bone, which is the larger of the two lower leg bones. You can feel this area as the bump on the inner side of your ankle joint. It bears 90 percent of the weight bearing load, so this is a common fracture.

Medial malleolar fractures involve the articular surface of the ankle joint, which is where the bones meet in the joint. The break may occur by itself but it normally accompanies injuries to the outside of the ankle or a fibula fracture of the smaller of the two lower leg bones. A majority of ankle fractures are the result of rotational forces. You step wrong and twist your foot inward or outward to cause the break.

Identifying if fracture ankle surgery is necessary for medial malleolus ankle fractures is usually straightforward. Whether you will need surgery or just casting depends on the entire ankle injury.

The 5 Kinds Of Medial Malleolar Fractures

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Dr. Neal Blitz

It’s important to understand the anatomy of the ankle in order to understand how medial malleolar fractures impact ankle fractures.

  • The tibia bone and the fibula bone make up the ankle.
  • The tibia bone makes up the knee joint and the ankle joint.
  • The fibula originates just below the knee and extends to the outer part of the ankle. It also provides the outer support of the ankle joint.
  • A strong ligamentous membrane keeps the two leg bones bound together. It is supported by a strong ligamentous connection at the ankle level (called the ankle syndesmosis).

Medial malleolus fractures are classified by the actual orientation of the fracture line. The five kinds of fractures are:

  • Chip fractures
  • Transverse fractures
  • Oblique fractures
  • Vertical fractures
  • Comminuted fractures

Chip Fractures of the Medial Malleolus

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Dr. Neal Blitz

Chip fractures are the sign of ligament rupture on the inner side of the ankle. Rather than the force of the injury causing a bone break, the ligaments pull off directly where they attach to the bone. The ligament can pull off a small piece of bone as the ligament is ruptured.

This chip fracture is also known as an avulsion fracture. They are sometimes seen with simple ankle sprains. The presence of an avulsion fracture, however, may indicate a more severe injury.

When chip fractures occur and the ligament is fully ruptured, the ankle can splay open.

Transverse Fractures of the Medial Malleolus

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Dr. Neal Blitz

The transverse fracture occurs in the same direction as the ankle joint line and is generally a small bone fragment. While these fractures extend into the ankle joint, they do not extend into the weight bearing portion.

Oblique Fractures of the Medial Malleolus

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Dr. Neal Blitz

The oblique medial malleolar fracture generally occurs along with a rotational injury that starts on the outside of the ankle. It is associated with an oblique fibular fracture and often occur at the corner of the ankle joint.

The presence of an oblique medial malleolar fracture often suggests an unstable fracture and ankle surgery may be indicated. 

Vertical Fractures of the Medial Malleolus

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Dr. Neal Blitz

The vertical fracture usually occurs when the force is oriented more in the leg bone. These fractures can extend into the weight-bearing portion of the ankle joint.

Comminuted Fractures of the Medial Malleolus

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Dr. Neal Blitz

Comminuted fractures of the medial malleolus are generally high-energy injuries that break the bone into multiple pieces.

When Is Ankle Surgery Necessary?

Your doctor will consider the injury to all parts of your ankle when deciding whether to recommend surgery. This is because ankle fractures typically occur as rotational injuries and you are likely to also have a fibular fracture.

Not all medial malleolar fractures require surgery. The bone will heal with or without surgery and it typically takes six to eight weeks for a bone to heal. The purpose of any surgery is to stabilize the bone in its proper position while the bone is healing.

In general, medial malleolar fractures that require surgery are those which are displaced, angular, or gape open. If the fractured segment of the ankle is unstable it may also call for surgery.

An important consideration is that these fractures can result in arthritis developing because they extend into the ankle joint and cause a misalignment of the cartilage surface. Surgery is often done to lessen this risk.

How a Surgeon Will Fix Your Ankle

The surgical repair of the medial malleolus fracture is generally dictated by the orientation of the fracture pattern. Broken bones may be fixed with wires, screws, screws with a plate, or any combination of these.

  • Vertically oriented fractures lend themselves to plate and screw fixes.
  • Oblique fractures are commonly fixated with screws that hold the bones together.
  • Transverse fractures can be repaired with screws and/or wire fixation techniques.
  • Some fractures are repaired with arthroscopic-assisted ankle fracture surgery.

Be sure to discuss your questions and concerns about ankle surgery with your physician.

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View Article Sources
  • Ankle Fractures (Broken Ankle). American Academy of Orthopaedic Surgeons. https://orthoinfo.aaos.org/en/diseases--conditions/ankle-fractures-broken-ankle/.