What degree of obliquity is required for the AP oblique, medial rotation, of the ankle?

• A. 20°
• B. 30°
• C. 45°
• D. 60°

Answer: (C)

For the AP oblique, medial rotation, of the ankle, a 45° degree obliquity is required to properly visualize the ankle joint and its structures. When performing this projection, the patient’s foot needs to be rotated medially to enhance the visibility of the mortise joint space, which is crucial for assessing potential fractures or abnormalities in the ankle region.

The 45° rotation is ideal because it aligns the imaging plane with the anatomy of the ankle, allowing for a clear view of the talus, the joint space between the tibia and fibula, as well as the surrounding bones. This degree of obliquity optimizes the differentiation between the bony structures, providing important diagnostic information.

Other angles, such as 20° or 30°, would not provide adequate visualization of the mortise joint, leading to suboptimal imaging quality and possibly overlooking significant pathology. While a 60° rotation could provide some visualization, it goes beyond the recommended angle for this specific view, potentially obscuring the anatomy instead of clarifying it. Thus, 45° is the standard and correct degree of obliquity for this projection.