Objective Assessment of Regional Stiffness in Vastus Lateralis with Different Measurement Methods: A Reliability Study

Abstract

The objective of this study was to evaluate the reliability of four methods of assessing vastus lateralis (VL) stiffness, and to describe the influence of structural characteristics on them. The stiffness of the dominant lower-limb’s VL was evaluated in 53 healthy participants (28.4 ± 9.1 years) with shear wave elastography (SWE), strain elastography (SE), myotonometry and tensiomyography (TMG). The SWE, SE and myotonometry were performed at 50%, and TMG was assessed at 30%, of the length from the upper pole of the patella to the greater trochanter. The thickness of the VL, adipose tissue and superficial connective tissue was also measured with ultrasound. Three repeated measurements were acquired to assess reliability, using intraclass correlation coefficients (ICC). Pearson’s correlation coefficients were calculated to determine the relationships between methodologic assessments and between structural characteristics and stiffness assessments of the VL. Myotonometry (ICC = 0.93; 95%-CI = 0.89,0.96) and TMG (ICC = 0.89; 95%-CI = 0.82,0.94) showed excellent inter-day reliability whereas with SWE (ICC = 0.62; 95%-CI = 0.41,0.77) and SE (ICC = 0.71; 95%-CI = 0.57,0.81) reliability was moderate. Significant correlations were found between myotonometry and VL thickness (r = 0.361; p = 0.008), adipose tissue thickness (r = −0.459; p = 0.001) and superficial connective tissue thickness (r = 0.340; p = 0.013). Myotonometry and TMG showed the best reliability values, although myotonometry stiffness values were influenced by the structural variables of the supra-adjacent tissue.

Assessing the Effects of Aging on Muscle Stiffness Using Shear Wave Elastography and Myotonometer

“…The SWE measures the stiffness using the Young’s modulus and the compressive stiffness of a solid material, such as a soft tissue, when force is applied to the area and is represented as kilopascal (kPa), while the MyotonPRO measures the resistance to an external force that deforms the initial shape and is represented as Newton per meter (N/m). As the previous research mentioned, even though the term stiffness is commonly used to define the viscoelastic characteristics when assessing tissues, the two methods assess different types of stiffness [ 49 ].…”

Scapular Dynamic Muscular Stiffness Assessed through Myotonometry: A Narrative Review

“…Muscular stiffness, described as passive or dynamic [ 1 , 2 , 3 ], is a mechanical property that traduce the resistance offered to an action that leads to muscle tissue deformation [ 1 , 3 ]. More specifically, this muscular property derived from muscle structure and intrinsic material properties [ 4 ], namely from tendon [ 5 ], myofibrillar cross-bridges [ 5 ] (particularly titin filaments [ 6 , 7 ]) and muscular connective tissue [ 6 ].…”

“…More specifically, this muscular property derived from muscle structure and intrinsic material properties [ 4 ], namely from tendon [ 5 ], myofibrillar cross-bridges [ 5 ] (particularly titin filaments [ 6 , 7 ]) and muscular connective tissue [ 6 ]. The passive stiffness, commonly assessed with elastography methods [ 2 , 3 ], mainly represents the tissue adaptation [ 3 ] in it basal/passive status [ 8 ] and the baseline level of the stiffness [ 5 ]. The dynamic stiffness, assessed through myotonometry [ 9 ], is based on the free oscillation theory and results from the natural oscillation of the tissues, in response to a brief mechanical tap on the skin [ 10 ].…”

“…Muscle mechanical behavior has been studied for a long time [ 2 , 18 ]. In particular, muscular stiffness has been assessed by different non-invasive and reliable methods [ 1 , 2 , 3 , 4 , 18 , 31 ]: elastography [magnetic resonance (MR) [ 2 ], ultrasound shear wave [ 2 , 3 ] or strain [ 3 ]]; tensiomyography [ 3 ]; myotonometry [ 3 ]. …”

“…Among the different methods, the ultrasound elastography [shear wave or strain [ 3 , 18 ], which only perform a qualitative assessment based in a color scale [ 2 , 3 , 32 ]] and the MR elastography [ 2 , 31 , 33 ] have the advantage of combining the assessment of passive stiffness [ 1 , 2 , 3 ] with operator visualization of the structures of interest [ 18 , 33 ]. However, these methods are associated with high costs and requires specialized operator’s knowledge [ 3 , 18 ] and more assessment time [ 34 ].…”