The Effect of Suture-Button Fixation on Simulated Syndesmotic Malreduction: A Cadaveric Study

Background: The accuracy of reduction of distal tibiofibular syndesmosis disruptions has been associated with the clinical outcome. Suture-button fixation of the syndesmosis is a dynamic alternative mode of fixation. We hypothesized that with deliberate clamp-induced malreduction, suture-button fixation of the syndesmosis would allow a more anatomic post-fixation position compared with screw fixation. Methods: Forty-eight syndesmotic fixations were performed on twelve through-knee cadaveric specimens. The syndesmosis was destabilized and off-axis clamping was used to produce both anterior and posterior malreduction patterns. In twelve scenarios (six anterior and six posterior malreductions), syndesmotic screw fixation was used, followed by computed tomography. With tenacula holding the malreduction, the syndesmosis screws were exchanged for a suture-button construct and the specimens underwent a subsequent computed tomography scan. In the other twelve scenarios, the suture-button fixation was achieved first, followed by screw fixation. Standardized measurements of anterior-posterior and medial-lateral fibular displacement were performed by two observers blinded to the method of fixation. Results: With anterior off-axis clamping, the mean sagittal malreduction was 2.7 +/- 2.0 mm with screw fixation and 1.0 +/- 1.0 mm with suture-button fixation (p = 0.02). With posterior off-axis clamping, the sagittal malreduction was 7.2 +/- 2.3 mm with screw fixation and 0.5 +/- 1.4 mm with suture-button fixation (p < 0.01). No differences were observed between fixation types in the coronal plane (p = 0.20 for anterior malreductions and p = 0.06 for posterior malreductions). Conclusions: With deliberate malreduction in a cadaver model, suture-button fixation of the syndesmosis results in less post-fixation displacement compared with screw fixation. The suture button's ability to allow for natural correction of deliberate malreduction was greatest with posterior off-axis clamping.