SLR - November 2023 - Medapati
Title: Effects of Posterior Malleolar Fixation on Syndesmotic StabilityReference: Stake IK, Bryniarski AR, Brady AW, et al. Effect of Posterior Malleolar Fixation on Syndesmotic Stability. The American Journal of Sports Medicine. 2023;51(4): 997-1006.
Level of Evidence: Level V
Scientific Literature Review
Reviewed By: Venkatramesh Medapati
Residency Program: LIJ-FH
Podiatric Relevance: Fixation of posterior malleolar fractures in regard to syndesmotic instability has been discussed within the field and how it should be approached but no definitive approach has been defined. Multiple treatment options have been utilized for posterior malleolar fractures (PMFs) with syndesmotic instability consisting of anterior inferior tibiofibular ligament augmentation with suture tape, posterior malleolar screw fixation, and transsyndesmotic fixation with suture buttons. Due to the various options of treatment, the purpose of this article was to identify the most effective combination of fixation options consisting of transsyndesmotic suture buttons, posterior malleolar screws, and anterior inferior tibiofibular ligament (AITFL) augmentation using suture tape which is rather unique and would be helpful to understand which option is best in reestablishing the natural tibiofibular and ankle joint motion after sustaining a 25% or 50% PMFs. The authors hypothesized that there would be no difference in syndesmotic stability between the methods (posterior malleolar fixation with screws, transsyndesmotic fixation with suture buttons, and with the addition of anterior inferior tibiofibular ligament augmentation to both these methods)
Methods: The way the authors tested this was through a controlled laboratory study which consisted of using twenty lower leg cadaveric limbs. The 20 limbs were split into 2 groups which consisted of 10 limbs with a 25% PMFs and the other 10 limbs with a 50% PMFs. These specimens were subjected to biomechanical assessments using a six-degree freedom robotic arm in seven different conditions consisting of no syndesmosis injury, syndesmosis injury with PMF, transsyndesmotic SBs, transsyndesmotic SBs and AITFL augmentation, transsyndesmotic SBs and AITFL augmentation and posterior malleolar screws, posterior malleolar screws and AITFL augmentation, and posterior malleolar screws. Four biomechanical tests were carried out at both neutral and 30 degrees of plantarflexion, while a 5 camera motion capture system recorded the tibia, fibula, and talus position, in order to assess for internal rotation, external rotation, lateral and posterior drawer movements.
Results: Results of these tests showed that during internal rotation, posterior malleolar screw fixations with all of the repairs was most effective in restoring the syndesmotic stability but during external rotation, posterior malleolar screws with AITFL augmentation was the most effective. In regard to posterior and lateral drawer tests, the intact and injured situations showed only minor differences. When comparing both the groups (25% and 50% of posterior malleolar fractures), the treatment effectiveness did not differ greatly.
Conclusions: Based on this study, it was depicted that posterior malleolar screw fixation with AITFL repair yielded higher stability of the syndesmosis compared with the transsyndesmotic suture buttons. This was because the AITFL augmentation which gave more stability during external rotation when compared to transsyndesmotic screws alone. Authors concluded that their hypothesis was incorrect and that the posterior malleolar fixation with AITFL augmentation did make a difference with the syndesmotic stability. It’s important to keep in mind of how each fixation methods can help with syndesmotic stability and when posterior malleolar screw fixation with AITFL augmentation could be used.