Kinds of Medial Malleolus Fractures

Medial Malleolus ankle fractures refer to breaking the inner bone of the ankle. The medial malleolus is an anatomical region on the tibia bone, which is the larger of the ankle bones and bears ninety percent of the weight bearing load. Medial malleolar fractures involve the articular surface of the ankle joint. Fracturing the medial malleolus may occur by itself but usually accompanies injuries to the outside of the ankle (fibula fractures). A high majority of ankle fractures are the result of rotational forces that cause the ankle bones to break.

Identifying if fracture ankle surgery is necessary for medial malleolus ankle fractures is usually straightforward. However, the medial malleolus fracture needs to be taken into context of the entire ankle injury when considering surgery or casting.

It’s important to understand the ankle anatomy 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, and provides the outer support of the ankle joint. A strong ligamentous membrane keeps the two leg bones bound together, along with a strong ligamentous connection at the ankle level (called the ankle syndesmosis).

The 5 Kinds Of Medial Malleolar Fractures

The variants of medial malleolar ankle fractures. Dr. Neal Blitz

Medial Malleolus fractures are classified by on the actual orientation of the fracture line: 

  1. Chip Fractures
  2. Transverse Fractures
  3. Oblique Fractures
  4. Vertical Fractures
  5. Comminuted Fractures

Chip Fractures Of The Medial Malleolus

Ligaments ruptures that pull off bone may be part of an unstable ankle fracture. 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. Here the ligament pulls off a small piece of bone (fleck of bone) as the ligament is ruptured. This chip fracture is also known as an avulsion fracture. Sometimes avulsion fractures may be simple ankle sprains. The presence of an avulsion fracture, however, may indicate a more severe injury in the context of an ankle fracture. When chip fractures occur and the ligament is fully ruptured then ankle can splay open.

Transverse Fractures Of The Medial Malleolus

Transverse medial malleolar ankle fractures usually involve a small piece of bone. Dr. Neal Blitz

The transverse fracture line occurs on the same direction of the ankle joint line. These fractures are generally a small bone fragment. While these fractures extends into the ankle joint, however do not extend into the weightbearing portion of the ankle joint.

Oblique Fractures Of The Medial Malleolus

Oblique medial malleolar ankle fractures are the most common. Dr. Neal Blitz

The oblique medial malleolar fracture generally occurs along with a rotational injury that starts on the outside of the ankle, and is associated with an oblique fibular fracture. The presence of an oblique medial malleolar fracture often suggests an unstable fracture and ankle fracture surgery may be indicated. They generally occur at the corner of the ankle joint.

Vertical Fractures Of The Medial Malleolus

The vertical medial malleolus fracture can be fixed with screws or a plate with screws. Dr. Neal Blitz

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

Comminuted Fractures Of The Medial Malleolus

Comminuted fractures are when the medial malleolus is broken up into several small bone fragments. Dr. Neal Blitz

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

When To Have Medial Malleolar Ankle Fracture Surgery

The medial malleolar fracture needs to be evaluated in the context of the entire ankle when considering ankle fracture surgery. Because ankle fractures typically occur as rotational injuries and medial malleolar fracture commonly occurs in conjunction with fibular fractures. In general, medial malleolar fractures that are displaced, gaped open and/or angular generally require surgery. The presence of instability of the of the fracture segment and/or the ankle also call for surgery. An important consideration for medial malleolar fractures is that these fractures extend into the ankle joint, and mal-malignment of the cartilage surface may result in arthritis, and therefore is an indication for surgery as well.  In many situations, the surgeon may identify the fracture mechanism and surgery is necessary.

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, and/or screws with a plate. Vertically oriented fractures lend themselves to plate and screw fixation. 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.

Not all medial malleolar fractures require surgery. It’s important to recognize that the medial malleolus bone will heal with or without surgery and that the purpose of any surgery is to stabilize the bone in proper position while bone healing occurs. It takes 6-8 weeks for bone to heal.

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