Suture button versus syndesmosis screw fixation in pronation-external rotation ankle fractures: A minimum 6-year follow-up of a randomised controlled trial.

Objective: Randomised controlled trials (RCT) with short-term follow-ups have shown that, in treatment of syndesmosis injuries, a suture button device (SB) resulted in better radiographic and functional outcome compared to syndesmosis screw fixation (SS). However, only one RCT has reported long-term results; thus, the syndesmosis malreduction rates for both implants might increase during longer follow-up. The primary objective of this RCT was to evaluate the maintenance of syndesmosis reduction with the SS compared to the SB fixation in patients during a minimum follow-up of 6-years. The secondary objectives were to assess the post-traumatic osteoarthritis (OA) grade and the functional outcome.

Patients And Methods: At Oulu University Hospital, between January 2010 and December 2011, we enrolled 43 patients with Lauge-Hansen pronation-external rotation type 4/Weber C, ankle fractures with unstable syndesmosis. Patients were randomised to treatment with either a single 3.5-mm tricortical SS (22 patients) or an SB (21 patients). The mean follow-up was 7.1 years (range, 6.2-7.9). Syndesmosis reduction and OA grade was assessed with standing cone-beam computed tomography (CBCT) of both ankles. Malreduction was defined as >2 mm side-to-side difference in the mean width of the syndesmosis. OA was graded according to the Morrey & Wiedeman classification. The Olerud-Molander Ankle Outcome Score (OMAS) and a quality of life questionnaire (RAND 36-Item Health Survey) were used to evaluate functional outcome.

Results: Two syndesmoses in the SS group and one in the SB group were malreduced (P = 0.58). Moderate OA after a mean of 7 years post-injury was common. In the SS and SB groups, 9 of 16 and 11 of 13 patients, respectively, had one or more grades serious OA in the injured ankle than in the uninjured ankle (P = 0.11). The mean OMAS was 88 in the SS group and 78 in the SB group (difference between means 7.1, 95% CI: -7.0-21.1, P = 0.32). The RAND-36 results did not differ between groups.

Conclusion: The SS and SB maintained syndesmosis reduction equally well during follow-up. Our study findings also suggest that both methods result in moderate OA rates and the functional outcome is comparable between these two syndesmosis fixation methods.