Intra-articular load distribution in the human ankle joint during motion

Area of Science:

• Biomechanics
• Orthopedic research
• Medical device development

Background:

• Understanding ankle biomechanics is crucial for effective injury treatment.
• Previous studies lacked reliable methods for measuring intra-articular ankle forces under dynamic conditions.
• The validity of static force distribution data for dynamic ankle movements remained unconfirmed.

Purpose of the Study:

• To characterize a novel electro-mechanical thin-membrane force transducer for intra-articular ankle use.
• To validate the use of static loading methodologies for studying ankle force distribution.
• To investigate ankle joint forces during static and dynamic dorsiflexion and plantarflexion.

Main Methods:

• Developed and tested a novel thin-membrane force transducer for intra-articular application.
• Assessed sensor performance in terms of linearity, reproducibility, and sensitivity to moisture and shear forces.
• Implanted sensors in cadaveric ankles, applying axial loads and cycling through physiological ranges of motion under static and dynamic conditions.

Main Results:

• The force transducer demonstrated reproducible linear responses and was insensitive to moisture and shear forces.
• Medial and lateral malleolar-talar forces increased with dorsiflexion.
• No significant difference was found between forces measured under static versus dynamic conditions, validating static methodologies.

Conclusions:

• The developed force transducer is suitable for intra-articular ankle measurements.
• Static loading accurately reflects dynamic ankle force distribution, supporting its use in future research.
• Dorsiflexion generates forces causing distal fibula rotation and lateral translation, providing new insights into ankle biomechanics.