The posterior inferior tibiofibular ligament (PITFL) runs obliquely from the posterior tubercle of the distal tibia to the posterior fibula, forming the main posterior wall of the ankle syndesmosis. Its deep portion is the inferior transverse ligament (already documented separately), which projects inferiorly to form the posterior ankle labrum. Together with the AITFL and interosseous ligament it forms the syndesmotic complex.
Primary posterior restraint of the ankle syndesmosis; resists internal rotation of the fibula; the deepest component forms the posterior ankle labrum.
The PITFL is the strongest of the syndesmotic ligaments and the last to rupture in progressive external rotation ankle injuries. Its intact status in high ankle sprain may allow conservative management, while PITFL rupture indicates complete syndesmotic disruption requiring surgical fixation. MRI demonstrates PITFL tears as loss of the normal low-signal posterior fibular ligamentous band. Posterior ankle impingement can involve the PITFL at its tibial insertion.
PITFL tear as part of complete syndesmotic disruption in high-energy external rotation ankle fracture-dislocation, indicating the most severe grade of syndesmotic injury requiring stable fixation before mortise congruence can be restored.
Avulsion of the posterior tibial tubercle (Volkmann fragment) at the PITFL attachment in ankle fractures, producing an unstable posterior mortise that requires fixation to restore posterior column stability.
