5 Kinds of Medial Malleolar Fractures

Deciding When Ankle Surgery Is Needed or Not

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% 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.

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

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 severity of the ankle injury.

Chip Fractures

Ankle-Fracture-NYC-Medial-Malleolus-Avulsion-1.jpg
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.

An avulsion fracture may require a cast or walking boot. In rare cases, if the bone fragment and main bone are too far apart to fuse naturally, surgery may be needed to reunite them. Avulsed bone fragments can be put back into place with fixation screws.

Transverse Fractures

Ankle-Fracture-NYC-Medial-Malleolus-Transverse-1.jpg
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.

Surgery is sometimes needed to stabilize a traverse fracture using cannulated screws. These are screws that are inserted through the skin using a hollow, narrow tube called a cannula.

Oblique Fractures

Ankle-Fracture-NYC-Medial-Malleolus-Oblique-1-.jpg
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 occurs at the corner of the ankle joint.

The presence of an oblique medial malleolar fracture is generally indicative an unstable ankle. Surgery is often recommended rather than casting, utilizing screws as well as wire fixation. It is not uncommon for a ruptured Achilles tendon to accompany an oblique fracture, requiring additional surgery to repair the torn or severed tendon.

Vertical Fractures

Ankle-Fracture-NYC-Medial-Malleolus-Vertical-1
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.

Vertical fractures of the medial malleolus may require more than just screws to stabilize the ankle. Oftentimes, fixation is achieved using a narrow metal plate with screws situated on both sides of the fracture line.

Comminuted Fractures

Ankle-Fracture-NYC-Medial-Malleolus-Comminuted.jpg
Dr. Neal Blitz

Comminuted fractures of the medial malleolus are generally high-energy injuries that break the bone into multiple pieces. Comminuted medial malleolus fractures can be technically challenging injuries to treat given the limited surface area by which a surgeon can reconstruct the bone fragments.

Oftentimes, a specialized device called a peg hook plate is used to repair comminuted fractures, allowing the surgeon to position screws in a non-linear pattern. The peg hook plate also accommodates different sized screws, minimizing the risk of further bone fragmentation or the loss of smaller bone chips.

A Word From Verywell

Your doctor will consider all aspects of an ankle fracture when deciding whether to recommend surgery or not. Not all medial malleolar fractures require surgery. The bone will heal with or without surgery in around six to eight weeks.

The purpose of surgery is to stabilize the bone in its proper position while the bone is healing. This can prevent the misalignment of ankle joint cartilage, a condition that can lead to post-traumatic osteoarthritis.

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

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