Three-Dimensional Comparison of Fibular Motion After Syndesmosis Fixation Using Combined Suture-Button and Internal Brace Constructs

Purpose The purpose of this study was to evaluate the ability of an internal brace to add sagittal plane translational and transverse plane rotational constraint to suture-button constructs with syndesmosis injuries. Methods 11 Fresh frozen cadaver ankles were stressed in external rotation using a custom-made ankle rig. Each ankle had simultaneous recording of ultrasound video, 6 DOF kinematics of fibula and tibia, and torque as the ankle was stressed by an examiner. The ankles were tested in 6 different states:

1. Native uninjured
2. Injured with IOL and AITFL sectioned
3. 1x Suture-button
4. 2x Suture-buttons, divergent
5. 1x Internal Brace with 2x Suture-buttons, divergent
6. 1x Internal Brace with 1x Suture-buttons Results Only the internal brace + 2x suture-buttons and internal brace + 1x suture-button constructs were found to be significantly different than the injured state (P=.0003, P=.002) with mean external rotation of the fibula. Conclusion Overall, the most important finding of this study was the addition of an internal brace to suture-button constructs provided a mechanism to increase external rotational constraint of the fibula. This study provides a mechanistic understanding of how the combined suture-button and internal brace construct provides an anatomically similar reconstruction of constraints found in the native ankle. However, none of the constructs examined in this study were able to fully restore physiologic motion.