The Agreement and Correlation Between Shear-Wave Elastography, Myotonometry, and Passive Joint Stiffness Measurements: A Brief Review

This brief review article was conducted to summarize the findings regarding correlation and agreement between different methods to assess muscle stiffness (shear wave elastography (SWE), myotonometry, and passive joint stiffness measurements). Muscle stiffness, an important biomechanical characteristic, influences joint flexibility, postural stability, injury risk, and athletic performance. SWE provides insights into tissue elasticity by measuring the propagation speed of shear waves, while myotonometry assesses stiffness through induced muscle oscillations. Passive joint stiffness measurements offer a holistic perspective, capturing the resistance of the entire joint to movement. However, distinguishing the contributions of muscular and non-muscular tissues remains a challenge in this method. The article highlights the variability in the correlation between these methodologies, influenced by factors such as muscle length, age, and examiner technique. While some studies report good agreement between SWE and myotonometry, others note discrepancies, underscoring the need for careful method selection based on the research or clinical context. This review highlights the complexity of assessing muscle stiffness and the necessity of a nuanced approach in interpreting data from different measurement techniques, aiming to guide researchers and clinicians in their choice of method for a precise and accurate evaluation of muscle stiffness.