To compare the biomechanical characteristics of suture-button fixation versus ligament reconstruction using semitendinosus tendon autograft in treatment of syndesmotic injury in cadaver biomechanical study. Eight matched pairs of human cadaveric lower-extremities were measured intact, then following simulated syndesmosis injury by cutting the anterior tibiofibular ligament (AITFL), the distal 15 cm of the interosseous membrane (IO), and the deltoid ligament. Thereafter, the syndesmotic injury was treated by suture-button fixation or ligament reconstruction. The semitendinosus tendon was harvested as a graft. Biomechanical testing was performed after the surgical fixation. The foot underwent rotation from neutral position to an external rotation at a rate of 5°/s to 12.5 Nm. The three-dimensional syndesmotic diastasis readings, final rotation torque, and rotational angle were recorded. No difference was found in fibular displacements between two groups. Moreover, no significant difference was found in final rotation torque (11.95 ± 1.03 VS 11.66 ± 1.18 Nm, P = 0.62) and rotation angle (43.61° ± 14.77° VS 40.93° ± 10.94°, P = 0.56) in the suture-button group and ligament reconstruction group. The stability of the suture-button fixation was equivalent to ligament reconstruction using semitendinosus tendon autograft in treatment of syndesmotic injury as determined with biomechanical testing. However, this study does not prove that one is advantageous over the other.