Distal fibular malrotation and lateral ankle contact characteristics

Area of Science:

• Orthopedic biomechanics
• Anatomy and physiology
• Surgical outcomes

Background:

• Malreduction of the syndesmotic joint negatively impacts functional outcomes.
• The precise degree of malrotation causing clinically relevant pressure changes remains unquantified.

Purpose of the Study:

• To investigate the association between small degrees of external and internal malrotation and significant changes in tibiofibular and talofibular joint contact pressure.

Main Methods:

• A controlled biomechanical study using twelve cadaveric ankles.
• Distal fibula osteotomy with a rotatable plate.
• Contact pressure and area measurement at varying degrees of malrotation (0°, 5°, 10° external/internal) across ankle motion.

Main Results:

• External rotation (5°, 10°) significantly decreased talofibular contact pressure in plantarflexion.
• Internal rotation (10°) significantly increased tibiofibular contact pressure in plantarflexion.
• Contact area varied significantly with rotation and plantarflexion, with external rotation decreasing and internal rotation increasing it.

Conclusions:

• Any external rotation of the distal fibula significantly reduces talofibular joint contact pressure during plantarflexion.
• Mild internal rotation (5°) caused minimal pressure changes, but 10° internal rotation significantly increased pressure in both tibiofibular and talofibular joints.
• These findings support clinical observations linking subtle fibular malrotation to altered lateral ankle mechanics.