The ankle joint itself (talocrural joint) is the articulation between the trochlear surface of the talus (top) and the distal ends of the tibia and fibula. The fibula may support 15-20 per cent of the bodyweight, with the fibula moving downwards and laterally during the stance phase of running to deepen the ankle mortise and enhance stability. This fibular motion creates tension in the interosseous membrane and tibiofibular ligament to provide some shock attenuation. Loss of this mechanism through tibiofibular disruption greatly affects the ankle joint, with a 1-2 mm lateral shift of the fibula increasing joint forces by as much as 40 per cent.