Varying Distance Between Suture Buttons Does Not Improve Stability of the Transected Syndesmosis and Deltoid Ligament in a Motion-Tracking Cadaveric Model

Background: A growing body of evidence favors the use of dynamic fixation techniques such as suture button fixation over rigid screw fixation for syndesmotic injuries. However, specific dynamic fixation techniques have been poorly evaluated. Purpose: To compare single suture button (SEB) fixation to double fixation with suture buttons placed 1 cm apart (DSEB 1) and double fixation with suture buttons placed 3 cm apart (DSEB 3). Study Design: Controlled laboratory study. Methods: A total of 24 lower leg specimens from 12 cadavers were tested using a custom biaxial apparatus. Internal rotation, external rotation, and anterior and posterior translation of the tibia and fibula were examined using motion-tracking systems after transection of deltoid and syndesmotic ligaments to compare 3 syndesmotic repair techniques: (1) an SEB placed 1 cm above the joint line, (2) 2 suture buttons placed 2 and 3 cm above the joint line, and (3) 2 suture buttons placed 1 and 4 cm above the joint line. Results: All 3 button constructs improved the stability of the syndesmosis by reducing aberrant motion after transection. There was no clear superiority of SEB, DSEB 1, or DSEB 3. DSEB 3 and DSEB 1 showed equal median laxity for tibial internal rotation (2.7°; DSEB 1, 2.0° to 3.2°; DSEB 3, 2.3° to 2.8°), tibial external rotation (–0.2°; DSEB 1, –0.4° to 0.4°; DSEB 3, –0.4° to 0.3°), and fibular external rotation (–0.3°; DSEB 1, –0.7° to 0.3°; DSEB 3, –0.7° to 0.7°). Conclusion: We found that utilization of a second suture button does not contribute additional stability to the syndesmosis after transection of the major syndesmotic ligaments. Moreover, we found that wider spread of 2 buttons (1 cm vs 3 cm apart) also did not confer additional stability. Future research should build upon these findings to further investigate the optimal configuration of suture button constructs. Clinical Relevance: Our study provides a framework for clinicians to reconsider syndesmotic suture button repair techniques based on our finding that there appears to be no enhanced syndesmotic stability with additional buttons.