November 2018

Assessing the elastic properties of skeletal muscle and tendon using shearwave ultrasound elastography and MyotonPRO

Authors: Y. N. Feng, Y. P. Li, C. L. Liu & Z. J. Zhang

Affiliations: Luoyang Orthopedic Hospital of Henan Province, Orthopedic Hospital of Henan Province, Luoyang, China

Journal: Nature - Scientific Reports - November 2018, Volume 8, Article no. 17064 (DOI: 10.1038/s41598-018-34719-7)

Background: The purposes of this study were to compare Young’s modulus values determined by shear wave ultrasound elastography (SWUE) with stiffness index obtained using a hand-held MyotonPRO device on the resting stiffness of gastrocnemius muscle belly and Achilles tendon; and to examine the test-retest reliability of those stiffness measurement using hand-held MyotonPRO.

Objective: There is a need to develop easily accessible and cost-effective clinical tools to assess the health of tissue mechanical properties. Thus, we undertook a study to better understand how well digital palpation device (MyotonPRO) measurements associated with SWUE measurements.

Access to a SWUE may be limited at large hospital and research institute. Procuring a SWUE is not always feasible in most clinics due to it is expensive and maintenance cost. A portable device equipped with the stiffness of muscle and tendon measurement function has a comparatively lower cost that is applicable for most small-scale clinics and research laboratory. More recently, a new hand-held device, called MyotonPRO, provides a reliable, accurate and sensitive way for the objective and non-invasive digital palpation of superficial skeletal muscles. It enables measurement not only of muscles, but also tendons. Thus, MyotonPRO may become a basic evaluation technique in muscle and tendon assessment as a portable and convenient diagnostic and monitoring device in medical practice.

Method: Twenty healthy volunteers participated in the study. The measurement values of muscle and tendon was determined in dominant legs. Each marker point was assessed using MyotonPRO and SWUE, respectively. Intra-operator reliability of MyotonPRO was established in 10 of the subjects. The correlation coefficients between the values of muscle and tendon stiffness indices determined by MyotonPRO and SWUE were calculated.

Results: Significant correlations were found for muscle and tendon stiffness and Young’s modulus ranged from 0.463 to 0.544 (all P < 0.05). The intra-operator reliability ranged from good to excellent (ICC(3,1) = 0.787~0.928).

Our findings were that both the gastrocnemius muscle belly and Achilles tendon stiffness indices determined with MyotonPRO were strong associated with Young’s modulus determined with SWUE.

In summary, the present study demonstrates that the gastrocnemius muscle belly and Achilles tendon stiffness measured by MyotonPRO is related to the Young’s modulus of those muscle and tendon quantified by SWUE. The MyotonPRO shows good intra-operator repeatability. Therefore, the present study shows that MyotonPRO can be used to assess mechanical properties of the gastrocnemius muscle belly and Achilles tendon with a resting condition.