AP and Oblique Toes Radiographic Evaluation and Positioning Errors

Vocabulary practice cards covering radiographic evaluation criteria, image appearances, and corrective actions for positioning errors in AP and Oblique toe radiography.

AP Toes Evaluation Criteria

The standard criteria requiring the CR to be $10\text{-degrees}$ posteriorly angled to the base of the $3^{\text{rd}}$ metatarsal, open IP & MTP joints, and equal concavity & soft tissue on both sides of the digit.

Medial/Lateral Rotation (AP Toes)

A positioning error appearing as unequal concavity and soft tissue on one side of the digit (larger concavity/soft tissue on one side indicates rotation towards the opposite side, e.g., more soft tissue on the medial side indicates lateral rotation); fixed by rotating the digit in the opposite direction until parallel with the IR.

Incorrect CR Angulation (AP Toes)

A positioning error appearing as narrowed/foreshortened IP & MTP joints and shortened toes; corrected by angling $10-15\text{ degrees}$ towards the heel.

Incorrect Centering (AP Toes)

A positioning error that appears as clipped distal phalanges and distorted joint space; fixed by centering to the correct MTP joint of interest.

Flexion (AP Toes)

A patient positioning error appearing as shortened phalanges and closed IP joints; fixed by extending the toes until flat against the IR.

Motion (AP Toes)

An artifact appearing as blurred cortical edges (outer edges of bones); fixed by using a shorter exposure time and providing increased patient support.

Oblique Toes Evaluation Criteria

The standard criteria requiring a $30-45\text{ degree}$ foot rotation, more concavity on one side of the digit, CR perpendicular to the joint of interest, and open MTP and IP joints.

Underrotation (Oblique Toes)

A positioning error appearing as an AP x-ray with equal concavity and soft tissue on both sides; fixed by increasing rotation $45\text{-degrees}$.

Overrotation (Oblique Toes)

A positioning error appearing as a lateral x-ray with superimposed metatarsal heads and phalanges; corrected by decreasing rotation.

Rotation Direction Error (Oblique Toes)

A positioning error resulting in the digit of interest being superimposed by adjacent toes; fixed by rotating medially for digits $1-3$ and rotating laterally for digits $4$ and $5$.

Lack of Parallelism (Oblique Toes)

A positioning error appearing as narrowed/closed IP joints; fixed by ensuring toes are parallel to the IR, using a sponge or other support if needed.

Incorrect Centering (Oblique Toes)

A positioning error appearing as a distorted joint of interest with adjacent toes dominating the field of view; corrected by properly centering to the MTP joint of interest.