A cadaveric study investigating the role of the anterior inferior tibio-fibular ligament and the posterior inferior tibio-fibular ligament in ankle fracture syndesmosis stability

Background: This cadaveric study aimed to investigate the role AITFL and PITFL have on preventing talar shift in ankle fractures, as well as investigating the role of AITFL reconstruction in preventing talar shift.

Methods: Twelve lower limb cadavers were used. Talar shift was measured following: Step 1- no ligaments cut; Step 2- entire deltoid ligament division; Step 3- group A (5 specimens) PITFL cut whilst group B (7 specimens) AITFL cut; Step 4- group A had AITFL divided whilst group B had PITFL cut. Reconstruction of the AITFL was performed using part of the superior extensor retinaculum as a local flap. Measurement of talar shift was then repeated.

Results: With no ligaments divided, mean talar shift was 0.8mm for group A and 0.7mm for group B. When the deltoid ligament was divided, mean talar shift for group A was 4.8mm compared to 4.7mm in group B (P=1.00). The mean shift in group A after PITFL division was 6.0mm, increasing the talar shift by an average of 1.2mm. In group B after AITFL division mean talar shift was 8.3mm (P=0.06), increasing talar shift by an average of 3.6mm. After division of the second tibiofibular ligament, mean talar shift in group A measured 10.0mm and in group B was 10.9mm (P=0.29). Three times more talar shift occurred after the AIFTL was divided compared to the PITFL (P=0.06).

Conclusion: Consequently, repairing the PITFL in isolation (for example by fixation of a posterior malleolus avulsion fracture) may not adequately prevent talar shift; we feel consideration should also be given to reconstruction of the AITFL to augment the syndesmosis fixation, which may provide a stronger restoration of ankle stability.

Level of Clinical Evidence: 5.