The bone that is broken is the fibula, the smaller of the two bones in the lower leg. It is situated on the outside of the lower leg. The fibular fracture is located closer to the knee (proximal) end of the bone, rather than down by the ankle.

A Maisonneuve fracture is often accompanied by a severe ankle sprain called a syndesmosis injury. The ligament and connective tissue (interosseus membrane) holding the tibia and fibula together are torn.

Maisonneuve fractures and syndesmosis injuries occur most often in athletes. The foot is planted on the ground and the lower leg rotates around it. The force of the injury is translated through the interosseus membrane, travels up the leg, and exits through the top of the bone. The result is a proximal fibular fracture.

With a Maisonneuve fracture, there can even be a fracture of the tibia (the other lower leg bone) at the bottom near the ankle. It's important to rule out a Maisonneuve fracture with traumatic ankle injuries. An X-ray is needed to do this.