Syndesmosis nonunion with the Agility total ankle system has been associated with adverse radiographic findings such as radiolucency and migration. We analyzed radiographs and biomechanical data to determine whether the addition of a fibular plate was associated with improved findings related to syndesmosis union compared with results when two syndesmosis screws alone were used. Radiographs for 40 consecutive ankles with the Agility total ankle system with two syndesmosis screws were compared with radiographs for the subsequent 40 consecutive total ankle replacements with an added fibular plate. When all ankles were considered, syndesmosis nonconsolidation at 6–10 weeks was associated significantly with nonunion at 5–7 months. Syndesmosis nonconsolidation at 6–10 weeks in ankles with screws alone was significantly higher than in ankles with plates. The radiolucency rate at 5–7 months also was significantly higher in ankles with screws alone than in ankles with plates. In the biomechanical evaluation using full tibia and fibula sawbones, maximum compression force within the syndesmosis was measured using the ISCAN sensor (TekScan). The addition of the fibular plate allowed significantly higher compression than the use of screws alone.