A comprehensive study of pressure distribution in the ankle joint with inversion and eversion

Area of Science:

• Biomechanics
• Orthopedics
• Human Anatomy

Background:

• Understanding ankle joint load transfer is crucial for diagnosing pathologies.
• Articular cartilage contact patterns deviate from the norm in pathologic conditions.
• Direct measurement of ankle joint contact is essential for biomechanical analysis.

Purpose of the Study:

• Investigate the force transfer characteristics across the three facets of the ankle joint.
• Quantify changes in contact area and pressure under varying loads and positions.
• Determine the effects of inversion, eversion, dorsiflexion, and plantarflexion on ankle joint biomechanics.

Main Methods:

• Utilized five fresh-frozen human cadaver lower extremities.
• Tested specimens in 12 positions under three axial loads (490, 686, 980 N).
• Employed Fuji film as a pressure transducer, analyzing prints with a computerized video digitizer.

Main Results:

• Inversion/eversion in neutral or dorsiflexion decreased contact area and increased average high pressure.
• Plantarflexion resulted in lower contact area and higher average pressure compared to dorsiflexion/neutral flexion.
• Increased axial loading led to greater contact area but not significantly higher pressure.
• Medial facet contact area increased with inversion, lateral facet with eversion, particularly in dorsiflexion.
• Contact centroid shifted from anterior to posterior on the talus with movement from dorsiflexion to plantarflexion.

Conclusions:

• Ankle joint position significantly influences contact area and pressure distribution.
• Load magnitude affects contact area more than peak pressure.
• Findings provide baseline biomechanical data for understanding ankle joint function and pathology.