Do lateral ankle ligaments contribute to syndesmotic stability: a finite element analysis study

Whether the lateral ankle ligaments contribute to syndesmotic stability is still controversial and has been the subject of frequent research recently. In our study, we tried to elucidate this situation using the finite element analysis method. Intact model and thirteen different injury models were created to simulate injuries of the lateral ankle ligaments (ATFL, CFL, PTFL), injuries of the syndesmotic ligaments (AITFL, IOL, PITFL) and their combined injuries. The models were compared in terms of LFT, PFT and EFR. It was observed that 0.537 mm LFT, 0.626 mm PFT and 1.25° EFR occurred in the intact model (M#1), 0.539 mm LFT, 0.761 mm PFT and 2.31° EFR occurred in the isolated ATFL injury (M#2), 0.547 mm LFT, 0.791 mm PFT and 2.50° EFR occurred in the isolated AITFL injury (M#8). The LFT, PFT and EFR amounts were higher in the both M#2 and M#8 compared to the M#1. LFT, PFT and EFR amounts in M#2 and M#8 were found to be extremely close. In terms of LFT and PFT, when we compare models with (LFT: 0.650 mm, PFT: 1.104) and without (LFT: 0.457 mm, PFT: 1.150) IOL injury, it is seen that the amount of LFT increases and the amount of PFT decreases with IOL injury. We also observed that injuries to the CFL, PTFL and PITFL did not cause significant changes in fibular translations and PFT and EFR values show an almost linear correlation. Our results suggest that ATFL injury plays a crucial role in syndesmotic stability.