The anterior inferior tibiofibular ligament (AITFL) is the most commonly injured syndesmotic ligament, running obliquely from the anterior tibia to the anterior fibula. Its superficial distal bundle runs parallel and slightly inferior to the main ligament and is called the accessory AITFL or Bassett's ligament — this accessory bundle can impinge on the lateral talar dome in ankle dorsiflexion after sprain, producing anterolateral ankle impingement.
| Origin | Anterior distal tibia (Chaput's tubercle) |
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| Insertion | Anterior distal fibula (Wagstaffe's tubercle) |
| Actions | The most commonly injured syndesmotic ligament; resists external rotation of the fibula in the mortise; first to fail in high ankle sprain mechanism |
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Bassett's ligament (accessory AITFL) impingement on the lateral talar dome after inversion sprain produces anterolateral ankle pain on dorsiflexion. Arthroscopic resection of the impinging ligament stump relieves symptoms. The main AITFL is repaired or reconstructed in high ankle sprain surgery alongside the CFL and PTFL.
Bassett's ligament (accessory AITFL) impingement on the talar dome producing anterolateral pain on dorsiflexion managed with arthroscopic resection.