[1] The injury is caused by a combined abduction external rotation from an eversion force.
A fractured fibula in addition to detaching the medial malleolus will tear the tibiofibular syndesmosis.
This damages the ligaments on the inside of the ankle and fractures the fibula at the point of contact (usually just above the tibiofibular syndesmosis).
The vertical line they form represents the fibula of the person's right leg.
[4] English physician Percivall Pott experienced this injury in 1765 and described his clinical findings in a paper published in 1769.