Myotonometry for the evaluation of Achilles tendon mechanical properties: a reliability and construct validity study

Area of Science:

• Biomechanics
• Musculoskeletal research
• Medical device technology

Background:

• Assessing Achilles tendon stiffness is crucial for understanding lower limb biomechanics and injury mechanisms.
• Objective measurement tools are needed to complement traditional clinical assessments.

Purpose of the Study:

• To evaluate the intra-rater and inter-rater reliability of the MyotonPRO device.
• To assess the construct validity of the MyotonPRO for measuring Achilles tendon stiffness.

Main Methods:

• A reliability and construct validity study was conducted with 40 healthy participants.
• The MyotonPRO was used by two raters on two separate occasions, assessing the Achilles tendon in relaxed, 0° plantarflexion, and standing positions.
• Measurements were taken during isometric contractions (0-3 kg), with reliability analyzed using intraclass correlation coefficients (ICC).

Main Results:

• Very high intra-rater reliability (ICC_2,k 0.87-0.98) and high to very high inter-rater reliability (ICC_2,k 0.76-0.86) were observed.
• High to very high inter-session reliability (ICC_2,k 0.70-0.89) was also found.
• Moderate reliability was noted for specific conditions, such as 0.5 kg contraction (ICC_2,k 0.54-0.59) and the standing position (ICC_2,k 0.56).

Conclusions:

• The MyotonPRO is a reliable and valid instrument for evaluating Achilles tendon stiffness across different contraction levels and positions.
• The device shows promise for clinical implementation in assessing tendon tissue mechanical properties.