In the frontal plane, what is the approximate axis orientation of the ankle joint?

In the frontal plane, what is the approximate axis orientation of the ankle joint?

• A. 20-30 degrees in frontal plane
• B. 0-5 degrees
• C. 40-50 degrees
• D. 60-70 degrees

Answer: (A)

The ankle joint’s rotation axis is not aligned with a single cardinal plane; it sits oblique in the frontal plane, about 20–30 degrees. This tilt comes from how the tibia, fibula, and talus fit together—the mortise shape and the orientation of the ankle surfaces cause the axis to incline rather than run straight in the frontal plane. As a result, dorsiflexion and plantarflexion occur mainly in the sagittal plane, with a small frontal (inversion/eversion-like) component due to that obliquity. The other options are either too small or too large to reflect the typical frontal-plane orientation of the ankle axis.

The ankle joint’s rotation axis is not aligned with a single cardinal plane; it sits oblique in the frontal plane, about 20–30 degrees. This tilt comes from how the tibia, fibula, and talus fit together—the mortise shape and the orientation of the ankle surfaces cause the axis to incline rather than run straight in the frontal plane. As a result, dorsiflexion and plantarflexion occur mainly in the sagittal plane, with a small frontal (inversion/eversion-like) component due to that obliquity. The other options are either too small or too large to reflect the typical frontal-plane orientation of the ankle axis.