Hysteresis measurements in intact human tendon

Area of Science:

• Biomechanics
• Musculoskeletal research
• Tendon physiology

Background:

• Mechanical hysteresis in tendons is traditionally measured using in vitro tensile testing.
• In vitro methods have limitations in accurately representing in vivo tendon function due to displacement measurement and clamping issues.
• There is a need to measure tendon hysteresis under in vivo conditions to better understand intact tendon behavior.

Purpose of the Study:

• To quantify mechanical hysteresis in the human tibialis anterior (TA) tendon under in vivo conditions.
• To develop and validate a methodology for in vivo assessment of tendon hysteresis.
• To compare in vivo hysteresis measurements with established in vitro data.

Main Methods:

• Measurements were conducted on the tibialis anterior (TA) tendon in six male participants.
• The foot was immobilized on a dynamometer footplate.
• Tendon displacement during muscle stimulation and relaxation was recorded using ultrasonography.
• Moment data at various voltage levels (0-100% maximum) were combined with displacement data to create load-displacement curves.

Main Results:

• A hysteresis loop was generated from the load-displacement curves during contraction and relaxation.
• The measured area of the hysteresis loop was 19%.
• This in vivo result is consistent with in vitro tensile test findings for low-stress tendons.

Conclusions:

• The developed in vivo methodology allows for accurate assessment of tendon hysteresis.
• The human tibialis anterior tendon exhibits mechanical hysteresis consistent with its function in force transmission and joint control.
• This approach enables future longitudinal studies and in vivo assessments of tendon health and potential for overheating.