Fibula radiography

Baseline views and visualization

Standard diagnostics for distal fibular injuries (forming the lateral malleolus) include anteroposterior and lateral radiographs, as well as a special ankle mortise view (mortice view).

• The ankle mortise view is performed as an anteroposterior radiograph with the foot internally rotated by approximately 10 degrees. This eliminates structural overlap: the fibula is projected in isolation from the talus (talus), allowing a clear assessment of the lateral joint space. Widening of this space is a reliable sign of instability.
• The lateral view (lateral view) is absolutely mandatory, as many oblique fractures of the distal fibula are not visualized on anteroposterior radiographs.

Diaphyseal and proximal fractures

Tibial shaft injuries are accompanied by fibular fractures in 30% of cases. Conversely, if the fibula remains intact during a tibial fracture, there is a high risk of varus deformity of the lower leg due to the pull of the long flexors.

Isolated fibular fractures are extremely rare and usually result from direct physical trauma.

Important clinical rule: upon detecting a proximal fibular fracture, the radiologist is obligated to order or perform radiography of the ankle joint. Such an injury is often part of a Maisonneuve fracture (Maisonneuve fracture) — a severe combined injury involving a medial malleolus fracture or a massive tear of the ankle ligamentous apparatus.

Danis-Weber classification

The Danis-Weber system is used to evaluate lateral malleolus fractures (distal fibula). It is based on the localization of the fracture line relative to the talar dome and the structures of the tibiofibular syndesmosis:

1. Type A: The fracture line runs below the level of the syndesmosis.
2. Type B: The fracture is localized precisely at the level of the syndesmosis.
3. Type C: The fracture is located above the level of the talus. This type is almost always accompanied by syndesmotic injury and instability, requiring surgical reduction.

Drawback of the classification: it is based solely on bony landmarks and poorly reflects concomitant soft-tissue tears.

Lauge-Hansen injury patterns

The appearance and shape of the fibular fracture on a radiograph allow the radiologist to accurately determine the mechanism of injury (foot position and force vector) and predict occult ligamentous tears according to the Lauge-Hansen classification:

• Supination-Adduction (SAD): Low transverse fracture of the lateral malleolus below the joint line (corresponds to Weber A).
• Supination-External Rotation (SER): Typical oblique or spiral fracture at the joint level (Weber B). The fracture line runs from the superior-posterior to the inferior-anterior edge.
• Pronation-Abduction (PAB): Oblique comminuted fibular fracture at the level of the joint line.
• Pronation-External Rotation (PER): High spiral fibular fracture located 6 cm or more above the ankle joint line.

Features in children and adolescents

The growth plates (physes) of the distal lower leg bones close synchronously: the process begins in the center, moves to the medial part, and finishes laterally. Asymmetric visualization of the growth plates on a radiograph is a reason to suspect epiphyseal injury.

Adolescents may present with specific transitional fractures (Transitional fractures) associated with skeletal immaturity:

• Triplane fracture (Triplane fracture): Fracture lines run simultaneously in three planes (axial, sagittal, coronal). If the fibula is also fractured, this indicates an extremely severe rotational mechanism of injury.
• Juvenile Tillaux fracture (Juvenile Tillaux fracture): Intra-articular fracture (Salter-Harris type III) with avulsion of the anterior tibiofibular ligament. Unlike the triplane fracture, the fracture line does not extend into the coronal plane.

Class and exam questions

What else to study on this topic

• MRI and CT in occult ankle injuries
• Lauge-Hansen fracture classification: stages and mechanisms
• Transitional fractures in adolescents: Tillaux and Triplane
• Salter-Harris distal tibial fractures
• The concept of the ankle joint as an osteoligamentous ring

Other topics in the "Musculoskeletal System" section

Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.