A cadaveric comparison of the anterior inferior tibiofibular ligament (AITFL) versus the posterior inferior tibiofibular ligament (PITFL) in preventing talar shift in syndesmotic ankle injuries

J. Littlechild, A. Mayne, F. Harrold, G. Chami

Introduction: How best to stabilise the distal tibio-fibular syndesmosis following injury remains controversial. This study aimed to ascertain whether stabilising only the AITFL is enough to prevent talar shift, and to test a simple, novel technique to reconstruct the AITFL.

Methods: Twelve cadaveric specimens were used. Talar shift was measured following: 1- no ligaments cut; 2- entire deltoid ligament division; 3- group 1 (5 specimens) PITFL cut whilst group 2 (7 specimens) AITFL cut; 4- group 1 had AITFL divided whilst group 2 had the PITFL cut. Groups were compared using the unpaired Student's t-test. 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 1 and 0.7mm for group 2. When the deltoid ligament was divided, mean talar shift for group 1 was 4.8mm compared to 4.7mm in group 2 (P=1.00). The mean shift in group 1 after PITFL division was 6.0mm, increasing the talar shift by an average of 1.2mm. In group 2 after AITFL division mean talar shift was 8.3mm (P=0.06), increasing talar shift by an average of 3.6 mm. After division of the second tibiofibular ligament, mean talar shift in group 1 measured 10.0mm and in group 2 was 10.9mm(P=0.29). Following sole reconstruction of the AITFL, mean talar shift was 3.7mm compared to 10.5mm prior to reconstruction.

Conclusion: These results demonstrate a trend that the AITFL confers greater ankle stability than the PITFL. Three times more talar shift occurred after the AIFTL was divided compared to the PITFL. Repairing just the PITFL (for example by fixation of the posterior malleolus avulsion fracture) may not adequately prevent talar shift while reconstruction of the AITFL potentially restores ankle stability.