Systematic Review of Instrumented Measures of Skeletal Muscle Mechanical Properties: Evidence for the Application of Shear Wave Elastography with Children

Shear modulus of lower limb muscles in school-aged children with mild hypotonia

The objective of this study is to compare shear modulus of lower limb muscles between children with hypotonia versus typical development (TD) or developmental disorders associated with altered tone. Nineteen children with mild hypotonia (mean age 9.4 ± 2.3y, 13 male) completed assessment of resting shear modulus of rectus femoris, biceps femoris (BF), tibialis anterior (TA) and gastrocnemius lateralis (GL) at short and long lengths using shear wave elastography. Data was compared with previous data from TD children and a scoping review for children with developmental disorders. Data were collated according to Net-Longitudinal Tension Angle (Net-LTA), which is the muscle length expressed as the net proximal and distal joint angles. Effects of Net-LTA (e.g., short, neutral, long) were examined according to sex, age and body mass index (BMI). In children with hypotonia, shear modulus was: higher at longer versus shorter lengths for four muscles (p < 0.01); correlated with age for BF-short (r = 0.60, p < 0.03) and GL-short (r = -0.54, p < 0.03), with BMI for BF-short (r = 0.71, p < 0.05); and not different between sexes (p > 0.05). The shear modulus values for lower limb muscles for children with mild hypotonia were lower than those for children with Duchenne Muscular Dystrophy (TA-neutral), or Cerebral Palsy (GL-neutral), but not TD children (all four muscles). In conclusion, shear modulus increases with longer muscle length (i.e. higher Net-LTA) in mildly hypotonic children. Children with mild hypotonia have lower shear modulus than children with cerebral palsy and Duchenne muscular dystrophy.

Participation measures that evaluate attendance and involvement for young people aged 15 to 25 years with cerebral palsy: a systematic review

PURPOSE

To identify participation-focused measures used for young people with cerebral palsy (CP), evaluate their psychometric evidence, and map item content to the International Classification of Functioning, Disability, and Health (ICF), and family of Participation-Related Constructs (fPRC) frameworks.

METHODS

Four databases (PubMed, Embase, Web of Science, CINAHL) were searched for papers that involved young people with CP aged 15 to 25 years and reported original data from a participation measure. Each measure was examined for validity, reliability, responsiveness (using the COSMIN checklist), clinical utility, the inclusion of accessible design features, self- and/or proxy-report from people with communication support needs, and item content according to ICF and fPRC.

RESULTS

Of 895 papers, 80 were included for review. From these, 26 measures were identified. Seven measures (27 papers/resources) were participation-focused, capable of producing a score for participation Attendance and/or Involvement. Of these, all measured Attendance (n = 7) but fewer than half measured Involvement (n = 3). Few included studies (37%) reported including some self-report of people with communication support needs.

CONCLUSIONS

Participation measures for young people with CP are evolving but require more: (i) emphasis on measurement of involvement; (ii) investigation of psychometric properties; and (iii) adaptation to enable self-report by young people with communication support needs.

Anisotropy and reproducibility of ultrasound shear wave elastography in patella tendons with and without tendinopathy

PURPOSE

Ultrasound shear wave elastography (SWE) is a tool that can be utilized to assess biomechanical properties of tendons. Anisotropy, an ultrasound imaging artifact has been commonly cited as a potential source of error in the accuracy and reproducibility of SWE. The aim of the study was to assess reproducibility in performing SWE of patella tendons and differences in SWE and anisotropy between normal patella tendons and patellar tendinopathy.

METHODS

After obtaining the Institutional Review Board approval and written informed consent, we prospectively measured the shear wave velocity (SWV) of patella tendons with and without tendinopathy in 25 volunteers. SWVs were measured in three anatomic planes: longitudinal, perpendicular transverse, and tilted transverse with the probe tilted 15-30° from the perpendicular transverse plane by three operators with varied levels of experience. Anisotropy coefficient (A) was calculated by formula of A = (SWVLongitudinal - SWVTransverse) / SWVTransverse.

RESULTS

Differences in SWV and anisotropy coefficient between normal tendons and tendons with tendinopathy were significant (p < 0.05). The intra- and inter-observer reproducibility in performing SWE were moderate to good (intraclass correlation coefficient: 0.81-0.95). The mean difference of 95% Bland-Altman limits of agreement for measuring tendon SWV ranged -0.08 to 0.41 (upper 0.08 to 1.14, lower -1.22 to -0.22) between senior and junior operators.

CONCLUSION

The results of this study suggest that SWE and anisotropy coefficient are feasible tools to differentiate patellar tendinopathy from normal patella tendons. The reproducibility of performing SWE of patella tendons is moderate to good.

Effects of two-week machine massage on muscle properties in adolescent wrestlers

Objective: This study aimed to investigate the effect of a two-week machine massage on the physical properties of the erector spinae and serum biochemical indexes of adolescent athletes after training. Methods: Sixteen male adolescent wrestlers were recruited (age: 15 ± 1 year; height: 166 ± 7 cm; weight: 56 ± 7 kg) and randomly assigned to machine massage (MA, 8) and control (CO, 8) groups. Participants in the MA group received machine massage for 20 min after each wrestling training from Monday to Saturday (except on Thursday) for two weeks, while the participants in the CO group recovered naturally. Over the course of two weeks, all the participants underwent similar wrestling training program under the guidance of a professional coach. Before and after the intervention, serum urea and creatine kinase (CK) levels were measured in a fasting state. A Myoton Pro digital muscle evaluation system was used to measure the physical properties of the erector spinae, including the oscillation frequency, logarithmic decrement of a muscle's natural oscillation, and dynamic stiffness. Results: After two weeks of machine massage treatment, the dynamic stiffness of the erector spinae in the MA group decreased by 12.90% and that in the CO group increased by 2.34%, indicating a significant difference between the two groups (p = 0.04, ƞ ² = 0.286). The decrease in the logarithmic decrement of a muscle's natural oscillation value in the MA was significantly greater than that in the CO (p = 0.003, ƞ ² = 0.286). Moreover, the serum CK values decreased by 33.84% in the MA group and by 1.49% in the CO group, despite a trend of change between the groups (p = 0.062, ƞ2 = 0.084). No significant difference was found in the improvement in serum urea levels between the two groups after two weeks of treatment. Conclusion: Results of the present study indicated that a two-week machine massage had a positive effect on the improvement of the physical properties of the erector spinae of wrestlers during training.

Variability of Biceps Muscle Stiffness Measured Using Shear Wave Elastography at Different Anatomical Locations With Different Ultrasound Machines

Shear wave elastography is an emerging diagnostic tool used to assess for changes in the stiffness of muscle. Each region of the muscle may have a different stiffness; therefore, the anatomical region should be carefully selected. Machine vendors each have unique methods for calculating the returned stiffness values and, consequently, a high level of agreement in measurement between machines (quantified using the intraclass correlation coefficient [ICC] and Bland-Altman analysis) will allow research findings to be translated to the clinic. This study assessed three locations within the biceps muscle (50% and 75% of the distance between the acromioclavicular joint and antecubital fossa, and superior to distal myotendinous junction [MTJ]) of 32 healthy volunteers with two different machines, the Canon Aplio i600 and SuperSonic Imagine Aixplorer (SSI), to compare the reported shear wave velocities and the variability by coefficient of variation (CV) and ICC. There was no difference in the CV between machines, but a significant difference in the CV at muscle regions, with the 75% location having a 40.2% reduction in CV. The 75% location had the highest ICC values with good posterior mean ICCs of 0.84 on the Canon and 0.83 on the SSI. The 50% and MTJ locations had poor ICC values. The 75% location provided the lowest CV and highest ICC and should be used for future stiffness assessments.

A biophysically guided constitutive law of the musculotendon-complex: modelling and numerical implementation in Abaqus

BACKGROUND AND OBJECTIVE

Many biomedical, clinical, and industrial applications may benefit from musculoskeletal simulations. Three-dimensional macroscopic muscle models (3D models) can more accurately represent muscle architecture than their 1D (line-segment) counterparts. Nevertheless, 3D models remain underutilised in academic, clinical, and commercial environments. Among the reasons for this is a lack of modelling and simulation standardisation, verification, and validation. Here, we strive towards a solution by providing an open-access, characterised, constitutive relation (CR) for 3D musculotendon models.

METHODS

The musculotendon complex is modelled following the state-of-the-art active stress approach and is treated as hyperelastic, transversely isotropic, and nearly incompressible. Furthermore, force-length and -velocity relationships are incorporated, and muscle activation is derived from motor-unit information. The CR was implemented within the commercial finite-element software package Abaqus as a user-subroutine. A masticatory system model with left and right masseters was used to demonstrate active and passive movement.

RESULTS

The CR was characterised by various experimental data sets and was able to capture a wide variety of passive and active behaviours. Furthermore, the masticatory simulations revealed that joint movement was sensitive to the muscle's in-fibre passive response.

CONCLUSIONS

This user-material provides a "plug and play" template for 3D neuro-musculoskeletal finite element modelling. We hope that this reduces modelling effort, fosters exchange, and contributes to the standardisation of such models.

Using Shear-Wave Elastography to Assess Exercise-Induced Muscle Damage: A Review

Shear-wave elastography is a method that is increasingly used to assess muscle stiffness in clinical practice and human health research. Recently, shear-wave elastography has been suggested and used to assess exercise-induced muscle damage. This review aimed to summarize the current knowledge of the utility of shear-wave elastography for assessment of muscle damage. In general, the literature supports the shear-wave elastography as a promising method for assessment of muscle damage. Increases in shear modulus are reported immediately and up to several days after eccentric exercise, while studies using shear-wave elastography during and after endurance events are showing mixed results. Moreover, it seems that shear modulus increases are related to the decline in voluntary strength loss. We recommend that shear modulus is measured at multiple muscles within a muscle group and preferably at longer muscle lengths. While further studies are needed to confirm this, the disruption of calcium homeostasis seems to be the primary candidate for the underlying mechanism explaining the increases in shear modulus observed after eccentric exercise. It remains to be investigated how well the changes in shear modulus correlate with directly assessed amount of muscle damage (biopsy).

Full Characterization of in vivo Muscle as an Elastic, Incompressible, Transversely Isotropic Material Using Ultrasonic Rotational 3D Shear Wave Elasticity Imaging

Using a 3D rotational shear wave elasticity imaging (SWEI) setup, 3D shear wave data were acquired in the vastus lateralis of a healthy volunteer. The innate tilt between the transducer face and the muscle fibers results in the excitation of multiple shear wave modes, allowing for more complete characterization of muscle as an elastic, incompressible, transversely isotropic (ITI) material. The ability to measure both the shear vertical (SV) and shear horizontal (SH) wave speed allows for measurement of three independent parameters needed for full ITI material characterization: the longitudinal shear modulus μL , the transverse shear modulus μT , and the tensile anisotropy χE . Herein we develop and validate methodology to estimate these parameters and measure them in vivo, with μL = 5.77±1.00 kPa, μT = 1.93±0.41 kPa (giving shear anisotropy χμ = 2.11±0.92 ), and χE = 4.67±1.40 in a relaxed vastus lateralis muscle. We also demonstrate that 3D SWEI can be used to more accurately characterize muscle mechanical properties as compared to 2D SWEI.

Muscle Ultrasonographic Elastography in Children: Review of the Current Knowledge and Application

Ultrasonographic elastography is a relatively new imaging modality for the qualitative and quantitative assessments of tissue elasticity. While it has steadily gained use in adult clinical practice, including for liver diseases, breast cancer, thyroid pathologies, and muscle and tendon diseases, data on its paediatric application is still limited. Moreover, diagnosis of muscular diseases in children remains challenging. The gold standard methods, namely biopsy, electroneurography, and electromyography, are often limited owing to their invasive characteristics, possible contraindications, complications, and need for good cooperation, that is, a patient’s ability to perform certain tasks during the examination while withstanding discomfort, which is a significant problem especially in younger or uncooperative children. Genetic testing, which has broad diagnostic possibilities, often entails a high cost, which limits its application. Thus, a non-invasive, objective, repeatable, and accessible tool is needed to aid in both the diagnosis and monitoring of muscle pathologies. We believe that elastography may prove to be such a method. The aim of this review was to present the current knowledge on the use of muscle elastography in the paediatric population and information on the limitations of elastography in relation to examination protocols and factors for consideration in everyday practice and future studies.

Stiffness of the Masseter Muscle in Children-Establishing the Reference Values in the Pediatric Population Using Shear-Wave Elastography

In children, the quality and muscle function are altered in many pathologic conditions, including temporomandibular disorders. Although several methods have been used to evaluate muscle tonus, none became a golden standard. Moreover, the masseter muscle characteristics in children have not been investigated to date. This study aimed to measure the stiffness of the masseter muscle using shear-wave elastography in healthy children. We enrolled 30 healthy children (mean age 10.87 ± 3.38 years). The stiffness of masseter muscles was measured with shear wave elastography. Stiffness for the total sample was 6.37 ± 0.77 kPa. A comparison of the measurements did not show significant differences between the right and the left masseter muscles (left—6.47 ± 0.78 kPa; right—6.24 ± 0.76 kPa; p = 0.3546). A significant difference was seen between boys and girls (boys—5.94 ± 0.50 kPa; girls—6.63 ± 0.80; p = 0.0006). Shear-wave elastography is a promising diagnostic tool. It may help to detect changes in the stiffness of the masseter muscle and draw attention to pathological processes within the jaw muscles. Directions for further research shall include determining stiffness values in pathological conditions and the impact of biological and functional factors on the stiffness of the masseter muscle.

Measuring skeletal muscle morphology and architecture with imaging modalities in children with cerebral palsy: a scoping review

AIM

To investigate the use of ultrasound and magnetic resonance imaging (MRI) methodologies to assess muscle morphology and architecture in children with cerebral palsy (CP).

METHOD

A scoping review was conducted with systematic searches of Medline, Embase, Scopus, Web of Science, PubMed, and PsycInfo for all original articles published up to January 2019 utilizing ultrasound and/or MRI to determine morphological and architectural properties of lower limb skeletal muscle in children with CP.

RESULTS

Eighty papers used ultrasound (n=44), three-dimensional ultrasound (n=16), or MRI (n=20) to measure at least one muscle parameter in children and adolescents with CP. Most research investigated single muscles, predominantly the medial gastrocnemius muscle, included children classified in Gross Motor Function Classification System levels I (n=62) and II (n=65), and assessed fascicle length (n=35) and/or muscle volume (n=35). Only 21 papers reported reliability of imaging techniques. Forty-six papers assessed measures of Impairment (n=39), Activity (n=24), and Participation (n=3).

INTERPRETATION

Current research study design, variation in methodology, and preferences towards investigation of isolated muscles may oversimplify the complexities of CP muscle but provide a foundation for the understanding of the changes in muscle parameters in children with CP.

WHAT THIS PAPER ADDS

Current evidence is biased towards the medial gastrocnemius muscle and more functionally able children with cerebral palsy (CP). Variations in imaging techniques and joint positioning limit comparisons between studies. Clinimetric testing of parameters of CP muscle is not always considered. Assessment of parameter(s) of muscle with measures of participation is sparse.

A profile of reference data for shear modulus for lower limb muscles in typically developing children

BACKGROUND

Shear wave elastography can measure shear wave speed in muscles, which is used to estimate shear modulus. Normative values and standardized methodology are needed for children. Study aims were to: estimate shear modulus behavior of lower limb muscles of typically developing children; and establish a profile of reference data and recommendations for clinical assessment.

METHODS

Forty-one typically developing children (mean 9.7 y, SD 1.9 y) completed assessment of resting shear modulus of rectus femoris, biceps femoris, gastrocnemius lateralis and tibialis anterior at short and long lengths using shear wave elastography. Effects of muscle length, age, sex and BMI were examined. Then, our data and data from a scoping review for typical individuals were collated according to Net-Longitudinal Tension Angle (net proximal and distal joint angles).

FINDINGS

Shear modulus was: higher at long versus short muscle lengths for all four muscles (P < 0.001); correlated with increasing age for tibialis anterior at short (r = 0.39) and long lengths (r = 0.42) (both P = 0.01); but not related to sex or BMI. Shear modulus: tended to increase with increasing Net-Longitudinal Tension Angle for 18 lower limb muscles; and was higher for children than adults for some muscles (e.g. tibialis anterior and gastrocnemius lateralis, both P < 0.001).

INTERPRETATION

In typically developing children, shear modulus of lower limb muscles increases with increasing Net-Longitudinal Tension Angle. Recommendations enable comparison of values across different test positions and populations. Some relation between shear modulus and age was identified, but more research is needed.