Which statement correctly describes the STJ axis orientation in the sagittal plane?

Which statement correctly describes the STJ axis orientation in the sagittal plane?

• A. 16 degrees medial in the sagittal plane.
• B. 16 degrees lateral in the sagittal plane.
• C. 30 degrees medial in the sagittal plane.
• D. 10 degrees medial in the sagittal plane.

Answer: (A)

The subtalar joint axis is oblique and does not lie in a single plane. In the sagittal view, its projection tilts toward the midline by about 16 degrees. That medial tilt means movements about this axis couple plantarflexion with inversion and adduction, and dorsiflexion with eversion and abduction, rather than being a pure sagittal motion. This approximate 16-degree medial orientation in the sagittal plane is the reason the correct statement is that the axis is 16 degrees medial in the sagittal plane.

The subtalar joint axis is oblique and does not lie in a single plane. In the sagittal view, its projection tilts toward the midline by about 16 degrees. That medial tilt means movements about this axis couple plantarflexion with inversion and adduction, and dorsiflexion with eversion and abduction, rather than being a pure sagittal motion. This approximate 16-degree medial orientation in the sagittal plane is the reason the correct statement is that the axis is 16 degrees medial in the sagittal plane.