Which projection demonstrates the distal tibia superimposed over the distal fibula?

Which projection demonstrates the distal tibia superimposed over the distal fibula?

• A. AP ankle
• B. Mortise
• C. Medial oblique
• D. Lateral ankle

Answer: (D)

In a true lateral ankle projection, the distal tibia and distal fibula lie in the same plane from the side, so their distal ends overlap. This specific superimposition happens because the leg is viewed in profile and the bones stack over one another, making the distal ends appear as one overlapped edge on the image. This overlapping is a useful check that the ankle is positioned correctly for a lateral view and helps assess alignment or potential dislocation. Other projections don’t emphasize this same superimposition as clearly. An AP ankle or the Mortise view is oriented to open joint spaces and assess the mortise—these views intentionally separate or tilt the bones a bit, so the exact distal tibia-over-distal-fibula overlap isn’t the defining feature. The medial oblique alters the relationship of the malleoli and reduces the consistent overlap seen on a true lateral.

In a true lateral ankle projection, the distal tibia and distal fibula lie in the same plane from the side, so their distal ends overlap. This specific superimposition happens because the leg is viewed in profile and the bones stack over one another, making the distal ends appear as one overlapped edge on the image. This overlapping is a useful check that the ankle is positioned correctly for a lateral view and helps assess alignment or potential dislocation.

Other projections don’t emphasize this same superimposition as clearly. An AP ankle or the Mortise view is oriented to open joint spaces and assess the mortise—these views intentionally separate or tilt the bones a bit, so the exact distal tibia-over-distal-fibula overlap isn’t the defining feature. The medial oblique alters the relationship of the malleoli and reduces the consistent overlap seen on a true lateral.