Background: Inaccuracy of ankle syndesmotic repair via reduction and trans-syndesmotic fixation can occur during ankle fracture repair. The goal of this study was to determine whether reduction and fixation of the posterior malleolar fracture (PM) fragment in rotational ankle fractures reduces the need for independent syndesmotic screw fixation.
Methods: A retrospective study was conducted using a consecutive series of patients treated operatively for a rotationally unstable ankle fracture with a PM fragment between 2011-2017. All ankle fractures underwent open reduction and internal fixation and divided into two groups: PM fixed or not fixed. An intraoperative stress evaluation of the ankle following bony fixation was performed in all cases to evaluate syndesmotic instability. Patient and fracture characteristics, and intraoperative instability and trans-syndesmotic fixation were compared between both groups.
Results: Eighty-five unstable ankle fractures that had a PM fragment were identified. Forty-three fractures underwent PM fixation and 42 did not. There were no differences between the PM fixation groups with regard to age, gender, body mass index or fracture pattern (p>0.183 for all). On average, PM fragments in the fixed group were larger than those not fixed (p<0.001). There were significantly lower odds of needing syndesmotic fixation if the PM fragment was reduced and fixed (p<0.001). Only 2 out of 43 ankles with a fixed PM fragment underwent syndesmotic fixation compared with 34 out of 42 non-fixed PM fragments.
Conclusion: Posterior malleolar fixation imparts syndesmotic stability and may obviate the need for trans-syndesmotic fixation for restoring dynamic ankle mortise congruence.Level of Evidence: III.
Keywords: ankle fractures; operative treatment; posterior malleolus.
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