In C1 fractures, there is fracture of the fibula above the level of the syndesmosis. It is usually a simple fracture. This is associated with
a rupture of the interosseus ligament between the distal tibia and fibula (syndesmosis), and the interosseous membrane up to the level of the fracture.
The medial side fails first in tension, either through the deltoid ligament (C1.1) or through a transverse avulsion fracture of the medial malleolus (C1.2). Very rarely, there may also be a fracture of the Volkmann's triangle (C1.3).
These are unstable injuries and the integrity of the syndesmosis must be restored.