Which statement about the ankle joint axis orientation is true?

Which statement about the ankle joint axis orientation is true?

• A. It is approximately 0 degrees in the transverse plane.
• B. It is approximately 20-30 degrees in the frontal plane.
• C. It is approximately 8 degrees in the transverse plane.
• D. It is approximately 60 degrees.

Answer: (C)

The key idea is that the ankle (tibiotalar) joint axis is not a pure hinge in one plane; it runs obliquely through multiple planes. In the transverse (horizontal) plane, this axis has a small tilt, about 8 degrees. That tiny transverse obliquity lets dorsiflexion and plantarflexion occur with a bit of rotation about the vertical axis, contributing to the ankle’s natural tri-planar motion.

So, the true orientation is a modest 8-degree tilt in the transverse plane. A zero tilt would imply a purely pure sagittal hinge with no coupled rotation, which doesn’t match how the ankle actually moves. A much larger tilt in the frontal plane or an orientation as large as 60 degrees doesn’t reflect the anatomical axis of the ankle.