Which statement is true for the AP mortise radiograph regarding rotation?

Which statement is true for the AP mortise radiograph regarding rotation?

• A. 0 degrees
• B. 15-20 degrees
• C. 30-40 degrees
• D. 45 degrees

Answer: (B)

In an AP mortise view, a small amount of internal rotation is used to open the ankle mortise and reduce overlap between the distal tibia and fibula. This helps you see the true joint space and assess the syndesmosis and alignment of the talus. About 15-20 degrees of internal rotation is the sweet spot: it clears the overlap without distorting the anatomy. Rotating 0 degrees leaves the tibia and fibula overlapped, making the mortise difficult to evaluate and hiding subtle injuries. Rotations far beyond the optimal range, like 30-40 or 45 degrees, distort the view, misrepresent the joint relationships, and can obscure or mimic pathology.

In an AP mortise view, a small amount of internal rotation is used to open the ankle mortise and reduce overlap between the distal tibia and fibula. This helps you see the true joint space and assess the syndesmosis and alignment of the talus. About 15-20 degrees of internal rotation is the sweet spot: it clears the overlap without distorting the anatomy.

Rotating 0 degrees leaves the tibia and fibula overlapped, making the mortise difficult to evaluate and hiding subtle injuries. Rotations far beyond the optimal range, like 30-40 or 45 degrees, distort the view, misrepresent the joint relationships, and can obscure or mimic pathology.