Final answer:
Superimposition of half of the fibular head by the tibia is evidence of a syndesmotic ankle sprain or 'high ankle sprain.'
Step-by-step explanation:
Superimposition of half of the fibular head by the tibia is evidence of a syndesmotic ankle sprain or 'high ankle sprain.' Above the ankle, the distal ends of the tibia and fibula are connected by a strong syndesmosis formed by ligaments and the interosseous membrane at the distal tibiofibular joint. Injuries that cause a lateral twisting of the leg can result in stretching or tearing of these ligaments, leading to the half of the fibular head being superimposed on the tibia.