Suture-Endobutton fixation is proposed as a minimally invasive, flexible fixation of ankle tibio-fibular diastasis, which would not require routine removal. This study tested the Suture-Endobutton construct in a cadaver syndesmosis injury model and compared this against A.O. syndesmosis screw fixation. Sixteen embalmed cadaver legs were used. Phase one consisted of placing the leg in a jig, generating an external rotation torque and measuring diastasis with increasing intraosseous membrane division. Phase two then compared the Suture-Endobutton construct vs. single four-cortex 4.5 mm A.O. screw fixation. Diastasis increased significantly with increasing intraosseous membrane division (p<0.001). No significant differences were seen in the mean rate of failure between the Suture-Endobutton and A.O. screw fixation. However, the Suture-Endobutton did give a significantly more consistent performance; the distribution of standard deviations for A.O. screw fixation was 0.64 mm higher than that for the Endobutton (95% C.I. 0.46 to 0.84). These results show that Suture-Endobutton fixation at least equals the performance of screw fixation and encourages clinical trials in ankle injuries with a syndesmosis diastasis.