In an AP oblique projection of the ankle, how is the ankle positioned?

In an AP oblique projection of the ankle, how is the ankle positioned?

• A. Placed with the leg rotated laterally 45 degrees
• B. Positioned so that the plantar portion of the foot is touching the image receptor
• C. Flexed at 90 degrees and the leg rotated medially 45 degrees
• D. Flexed 45 degrees to the image receptor with the foot rotated medially 30 degrees

Answer: (C)

In an AP oblique ankle, the goal is to show the ankle mortise clearly by positioning the leg so the distal tibia, fibula, and talus aren’t overly superimposed. This is best accomplished when the knee is flexed to a right angle and the entire leg is rotated medially about 45 degrees. That medial rotation opens the mortise joint just enough to visualize its relationships, while keeping the ankle and foot in a stable, reproducible orientation on the image receptor. Rotating the leg laterally would produce a different oblique (external) view and not optimally open the mortise. Placing the plantar surface against the receptor would imply a specific foot position that doesn’t define the oblique ankle projection. A 30-degree medial rotation or other knee angles would yield a different oblique alignment, not the standard mortise visualization that a 45-degree medial rotation with the knee at 90 degrees provides.

In an AP oblique ankle, the goal is to show the ankle mortise clearly by positioning the leg so the distal tibia, fibula, and talus aren’t overly superimposed. This is best accomplished when the knee is flexed to a right angle and the entire leg is rotated medially about 45 degrees. That medial rotation opens the mortise joint just enough to visualize its relationships, while keeping the ankle and foot in a stable, reproducible orientation on the image receptor.

Rotating the leg laterally would produce a different oblique (external) view and not optimally open the mortise. Placing the plantar surface against the receptor would imply a specific foot position that doesn’t define the oblique ankle projection. A 30-degree medial rotation or other knee angles would yield a different oblique alignment, not the standard mortise visualization that a 45-degree medial rotation with the knee at 90 degrees provides.