Distal tibiofibular syndesmosis injury

Last revised by Henry Knipe on 21 Jun 2023

Distal tibiofibular syndesmosis injuries are a relatively frequent ankle injury, although less common than a fracture or lateral ankle sprain. They are estimated to comprise ~10% (range 1-20%) of ankle injuries. 

The mechanism of injury is uncertain but thought to be the combination of forceful foot external rotation with concomitant leg internal rotation 2. Injuries can occur to one or more of the structures that make up the distal syndesmosis 1:

Distal syndesmotic injury can easily be inapparent and therefore missed on plain x-ray, especially if it is not accompanied by a nearby fracture or widening of the tibiofibular clear space 2,3. Numerous measurements have been proposed for indirectly demonstrating syndesmotic injury but these vary across studies with no formed consensus. Some studies have shown 3:

Aside from being readily available, ultrasonography has the added benefit of being a real-time dynamic modality, allowing the operator to perform maneuvers on the ankle during imaging. The contralateral, uninjured, ankle can be imaged for comparison.

It can demonstrate:

MRI has been shown to accurately detect injuries to the ligamentous structures of the distal tibiofibular syndesmosis 1-3. The anterior inferior tibiofibular ligament is the one most often involved in such injuries and the most convenient to identify 2. Direct signs of a ligamentous tear include 2,4:

  • abnormal course of the ligament

  • irregular contour of the ligament

  • inability to visualize the ligament

Indirect signs 4:

  • tibiofibular joint space fluid

  • prolapsed interspace fat

  • T2

    • acute ligamentous injury: hyperintense signal in the ligament with surrounding edema

    • chronic injury: thickened or disrupted ligament without edema

  • T1 C+

    • acute injury: injured ligaments enhance intensely

Surgical management options include an ORIF with syndesmotic screw(s) or a cord device, e.g. TightRope.

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