The syndesmotic ligament complex includes the anterior inferior tibiofibular ligament (AITFL), posterior inferior tibiofibular ligament (PITFL), transverse tibiofibular ligament, and interosseous ligament. Together they hold the distal tibia and fibula together to maintain the precise mortise width that grips the talus. Disruption widens the mortise, producing talus maltracking, increased joint stress, and early ankle arthritis if not corrected.
| Origin | Lateral tibial surface at the anterior and posterior tibial tubercles (Tillaux tubercle anteriorly) |
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| Insertion | Medial fibular surface at corresponding levels |
| Actions | Maintains the distal tibiofibular mortise width — critical for ankle mortise stability during loading |
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High ankle sprains (syndesmotic injuries) occur from external rotation forces and take two to three times longer to recover than lateral ankle sprains. The squeeze test (midcalf compression) and external rotation stress test reproduce pain in syndesmotic injuries. MRI shows fluid within the syndesmotic ligaments and interosseous membrane. Surgical stabilisation with a syndesmotic screw or suture button device is required for diastasis exceeding 2 mm.
Syndesmotic ligament disruption from external rotation producing diastasis and mortise widening, requiring prolonged rehabilitation or surgical stabilisation with screw or suture button.
