Interrater reproducibility of the Myoton and durometer devices to quantify sclerotic chronic graft-versus-host disease.

Chronic graft-versus-host disease (cGVHD) is a severe complication in long-term survivors of allogeneic hematopoietic stem cell transplantation. This disease is challenging to manage clinically due to a lack of validated tools to quantitatively measure skin sclerosis. The current gold standard for measuring skin sclerosis is the NIH Skin Score which has only moderate agreement among clinicians and experts. To more accurately assess skin sclerosis in cGVHD, the Myoton and durometer devices can be used to directly measure biomechanical parameters of the skin. However, the reproducibility of these devices is not known in patients with cGVHD. To determine this reproducibility, three observers independently measured 10 anatomic sites in each of seven patients with sclerotic cGVHD using the Myoton and durometer. Clinical reproducibility was measured by mean pairwise differences (U-statistic) and intraclass correlation coefficients (ICCs) with 95% confidence intervals (CIs). Mean pairwise differences, expressed in true physical units, were used to report typical errors for each anatomic site and device. Mean pairwise differences were less than 11% of the average overall values for all five Myoton parameters and durometer hardness. These were lower for Myoton creep (4.1%), relaxation time (4.7%), and frequency (5.1%) than decrement (9.0%), stiffness (10.4%), and durometer hardness (9.0%). Myoton parameters creep, relaxation time, and frequency showed promise for capturing skin biomechanics more accurately than Myoton stiffness, decrement, or durometer hardness. Mean pairwise differences trended highest in the shin and volar forearm and lowest in the dorsal forearm. The interobserver ICC for overall (averaged across all measured body sites of a patient) creep (0.94; 95% CI 0.87-1.00), relaxation time (0.96; 95% CI 0.90-1.00), and frequency (0.95; 95% CI 0.88-1.00), trended higher than that for decrement (0.43; 95% CI 0.00-0.88), stiffness (0.92; 95% CI 0.81-1.00), and durometer hardness (0.82; 95% CI 0.61-1.00). Similar trends were observed in healthy participants. These findings can help clinicians design better studies to assess therapeutic response to new cGVHD treatments and support the interpretation of future measurements.

Short-time recovery skeletal muscle from dexamethasone-induced atrophy and weakness in old female rats.

BACKGROUND: Several pathological conditions (atrophy, dystrophy, spasticity, inflammation) can change muscle biomechanical parameters. Our previous works have shown that dexamethasone treatment changes skeletal muscle tone, stiffness, elasticity. Exercise training may oppose the side effects observed during dexamethasone treatment. The purpose of this study was to examine the changes in biomechanical parameters (tone, stiffness, elasticity) of skeletal muscle occurring during dexamethasone treatment and subsequent short-time recovery from glucocorticoid-induced muscle atrophy and weakness, as well as the effect of mild therapeutic exercise. METHODS: 17 old female rats, aged 22 months were used in this study. The hand-held and non-invasive device (MyotonPRO, Myoton Ltd., Tallinn, Estonia) was used to study changes in biomechanical properties of muscle. Additionally, body and muscle mass, hind limb grip strength were assessed. FINDINGS: Results showed that dexamethasone treatment alters muscle tone, stiffness and elasticity. During 20-day recovery period all measured parameters gradually improved towards the average baseline, however, remaining significantly lower than these values. The body and muscle mass, hind limb grip strength of the rats decreased considerably in the groups that received glucocorticoids. After 20 days of recovery, hind limb grip strength of the animals was slightly lower than the baseline value and mild therapeutic exercise had a slight but not significant effect on hind limb grip strength. Biomechanical parameters improved during the recovery period, but only dynamic stiffness and decrement retuned to baseline value. INTERPRETATION: The study results show that monitoring muscle biomechanical parameters allows to assess the recovery of atrophied muscle from steroid myopathy.

Optimal biomechanical parameters for measuring sclerotic chronic graft-versus-host disease.

Skin biomechanical parameters (dynamic stiffness, frequency, relaxation time, creep, and decrement) measured using a myotonometer (MyotonPRO) could inform management of sclerotic disease. To determine which biomechanical parameter(s) can accurately differentiate sclerotic chronic graft-versus-host disease (cGVHD) patients from post-hematopoietic cell transplant (post-HCT) controls, 15 sclerotic cGVHD patients and 11 post-HCT controls were measured with the myotonometer on 18 anatomic sites. Logistic regression and two machine learning algorithms, LASSO regression and random forest, were developed to classify subjects. In univariable analysis, frequency had the highest overfit-corrected area under the receiver operating characteristic curve (AUC 0.91). Backward stepwise selection and random forest machine learning identified frequency and relaxation time as the optimal parameters for differentiating sclerotic cGVHD patients from post-HCT controls. LASSO regression selected the combination of frequency and relaxation time (overfit-corrected AUC 0.87). Discriminatory ability was maintained when only the sites accessible while the patient is supine (12 sites) were used. We report the distribution of values for these highly discriminative biomechanical parameters, which could inform assessment of disease severity in future quantitative biomechanical studies of sclerotic cGVHD.

Development of Garments with Elastic Straps and Pressure Applicator (GESPA) and "GVcorrect" App to Follow the Changes in Lower-Extremity Alignment (Genu Valgum)-A Pilot Study.

BACKGROUND: There are non-invasive methods of correcting genu valgum (GV), but to date, there is no method to evaluate mechanotherapeutic intervention that does not restrict child's natural movements while the process is on-going so that timely decisions could be made on effectiveness of intervention. The aim of study was to develop and assess the comfortability of garments with elastic straps and pressure applicator (GESPA) and the reliability and user-friendliness of "GVcorrect" app, which aims to catch the elastic straps' pressure level (mN). METHODS: 6 children (5-7 y) with intermalleolar distance ≥5 cm wore GESPA daily for 3 months. Anthropometrical and goniometrical measurements were done according to standard technique; tone and biomechanical parameters of skeletal muscles determined with MyotonPRO; feedback about GESPA and "GVcorrect" collected via questionnaire. RESULTS: Based on feedback from children and parents, new, more comfortable and user-friendly GESPA were designed; several updates were made to "GVcorrect" app; new goals were set for the next phase of the study. CONCLUSIONS: GESPA and the "GVcorrect" app serve their purpose, but there are still a number of important limitations that need to be removed before the product can be marketed. The study continues with product development until a medical device certificate is obtained.

Correction: Non-invasive measurement of sclerosis in cutaneous cGVHD patients with the handheld device Myoton: a cross-sectional study.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Reproducibility of the durometer and myoton devices for skin stiffness measurement in healthy subjects.

BACKGROUND: Clinical assessment of skin stiffness is unreliable in many applications. The durometer, an industrial device to measure hardness, has previously been applied in scleroderma. The Myoton is a noninvasive handheld device for assessing soft tissue biomechanical parameters. MATERIALS AND METHODS: We evaluated the reproducibility of both devices in six healthy subjects in the volar forearm, dorsal forearm, upper arm, shin, and calf bilaterally. The intraclass correlation coefficient (ICC) was used as a measure of reproducibility among three observers. RESULTS: The interobserver intraclass correlation coefficient (ICC) of overall stiffness for the Myoton was 0.74 [95% confidence interval (CI) 0.45-1.00] and 0.71 [0.39-1.00] for the durometer. Coefficient of variation (CV) for the Myoton was 6.4% [range 1.3-12.1] and 7.6% [range 4.4-13.8] for the durometer. Myoton and durometer values had a Pearson correlation of 0.69. The intraobserver Myoton ICC was 0.89 [0.74-1.00] and CV 3.1% [range 1.6-5.0]. The 95% confidence minimal detectable change by the Myoton for a single observer is 32.4 N/m, which is 7.6% of the average subject's overall stiffness. CONCLUSION: The Myoton demonstrated high reproducibility, particularly in the overall stiffness parameter, and merits further investigation to assess disease progression and treatment efficacy.

Glucocorticoid-Induced Changes in Rat Skeletal Muscle Biomechanical and Viscoelastic Properties: Aspects of Aging.

OBJECTIVES: The purpose of this study was to estimate the state of tension (tone) and the biomechanical and viscoelastic properties of skeletal muscle in aging rats during the administration of different doses of dexamethasone and to find the relationships among the state of muscle atrophy, muscle strength, and the abovementioned muscle properties. METHODS: Muscle state of tension, biomechanical (elasticity, dynamic stiffness) and viscoelastic (mechanical stress relaxation time, Deborah number) properties (using MyotonPRO, Myoton Ltd, Tallinn, Estonia), lean body mass (BM), and hind limb grip strength were measured before and after the administration of a 10-day treatment with dexamethasone 100 µg/100 g BM (young and old group) and 50 µg/100 g BM (old group). RESULTS: Muscle elasticity (logarithmic decrement) was lower in old animals (1.86 ± 0.03) in comparison with young adult rats (1.38 ± 0.04) (P < .01). After the 10-day treatment with dexamethasone 100 µg/100 g BM, young adult rats had 10% lower muscle elasticity (P < .01). The same dose of dexamethasone in old rats increased tone (frequency of natural oscillation) from 29.13 ± 0.51 Hz to 38.50 ± 0.95 Hz (P < .001). There were dose-dependent differences in dynamic stiffness and tone of muscle; changes in elasticity were independent of the dose in old animals. In old rats, the muscle's viscoelastic properties decreased after dexamethasone administration. Significant correlation was found between changes in muscle logarithmic decrement and stiffness (rs = 0.90; P < .05) in old animals. CONCLUSIONS: Biomechanical and viscoelastic properties of skeletal muscle indicate changes in the main function of muscle during glucocorticoid-induced muscle atrophy and are in agreement with changes in hind limb strength. The myometric measurements indicate the direction and magnitude of change in muscle tissue after different doses of dexamethasone administration easily and quickly.

Assessment of skeletal muscle fatigue of road maintenance workers based on heart rate monitoring and myotonometry.

OBJECTIVE: This research work is dedicated to occupational health problems caused by ergonomic risks. The research object was road building industry, where workers have to work very intensively, have long work hours, are working in forced/constrained work postures and overstrain during the work specific parts of their bodies. The aim of this study was to evaluate the work heaviness degree and to estimate the muscle fatigue of workers after one week work cycle. The study group consisted of 10 road construction and maintenance workers and 10 pavers aged between 20 and 60 years. METHODS: Physical load were analyzed by measuring heart rate (HR), work postures (OWAS) and perceived exertion (RPE). Assessments of the muscles strain and functional state (tone) were carried out using myotonometric (MYO) measurements. The reliability of the statistical processing of heart rate monitoring and myotonometry data was determined using correlating analysis. RESULTS: This study showed that that road construction and repairing works should be considered as a hard work according to average metabolic energy consumption 8.1 +/- 1.5 kcal/min; paving, in its turn, was a moderately hard work according to 7.2 +/- 1.1 kcal/min. Several muscle tone levels were identified allowing subdivision of workers into three conditional categories basing on muscle tone and fatigue: I--absolute muscle relaxation and ability to relax; II--a state of equilibrium, when muscles are able to adapt to the work load and are partly able to relax; and III--muscle fatigue and increased tone. It was also found out that the increase of muscle tone and fatigue mainly depend on workers physical preparedness and length of service, and less on their age. CONCLUSION: We have concluded that a complex ergonomic analysis consisting of heart rate monitoring, assessment of compulsive working postures and myotonometry is appropriate to assess the work heaviness degree and can provide prognosis of occupational pathology or work-related musculoskeletal disorders for the workers under different workload conditions. These results can also be used when deciding on necessary rest time and its periodicity.

Obstructive sleep apnea and ageing Myotonometry demonstrates changes in the soft palate and tongue while awake.

Upper airway dilator muscles are important in the pathogenesis of obstructive sleep apnea syndrome (OSAS). The present study compares changes of tissue properties between the soft palate and tongue in different age groups of apnea patients and healthy subjects. Materials and methods: OSAS patients diagnosed by polysomnography (15 patients - aged 30-70 years; 10 patients - aged 18-29 years) and healthy volunteers (10 subjects - aged 30-70 years; 10 patients - aged 18-29 years) participated in the study. Computerized endopharyngeal myotonometry was used to measure the biomechanical properties - stiffness and elasticity of the soft palate [M. Veldi, V. Vasar, A. Vain, T. Hion, M. Kull, Computerized endopharyngeal myotonometry (CEM): a new method to evaluate the tissue tone of the soft palate in patients with obstructive sleep apnea syndrome, J. Sleep Res. 9 (2000) 279-284; M. Veldi, V. Vasar, T. Hion, M. Kull, A. Vain, Ageing, soft-palate tone and sleep-related breathing disorders, Clin. Physiol. 21 (2001) 358-364] and lingual tissues [M. Veldi, V. Vasar, T. Hion, A. Vain, M. Kull, Myotonometry demonstrates changes of lingual musculature in obstructive sleep apnea, Eur. Arch. Otorhinolaryngol. 259 (2002) 108-112; M. Veldi, V. Vasar, T. Hion, A. Vain, M. Kull, Myotonometry demonstrates changes of soft palate and genioglossal muscle in obstructive sleep apnea, Sleep Med. 4 (Suppl. 1) (2003) S49] during wakefulness. Results: We did not find any statistical differences in tissue properties between the soft palate and the tongue tissues, either stiffness or elasticity, in young non-snorers and young patients of apnea (P > 0.05). The stiffness of the soft palate of middle-aged apnea patients was increased compared with the tongue (P < 0.001). The elasticity of tongue of middle-aged patients of apnea was decreased compared with the soft palate (P < 0.001). Conclusions: The biomechanical properties of the soft palate and the tongue undergo different changes in the case of snoring and upper airway obstruction and ageing.

Myotonometry demonstrates changes of lingual musculature in obstructive sleep apnoea.

Upper airway dilator muscles are important in the pathogenesis of obstructive sleep apnoea (OSA). Previously, soft palate and tongue muscles of patients with OSA have been studied from a histological point of view. Electromyographic studies revealed increased activity of upper airway dilator muscles. We used computerized endopharyngeal myotonometry (CEM) to measure the biomechanical properties of lingual musculature, mainly the genioglossal muscle, to characterize changes of tongue muscles in patients with OSAS. The method records and analyzes the response of the tongue sublingually after a brief mechanical impact. It enabled us to evaluate the most important parameters of tissue tone--stiffness, which is expressed as a frequency, and elasticity, as a logarithmic decrement of the damped oscillation. The results of CEM indicated that patients with OSAS show an increased stiffness (14.1 +/- 0.7 Hz) of the tongue in comparison with non-snoring subjects (11.5 +/- 0.2 Hz). The elasticity of the tongue is decreased, which is numerically expressed as an increased decrement (4.0 +/- 0.2) in patients with OSA in comparison with non-snorers (2.2 +/- 0.2). Changes in the biomechanical characteristics of lingual musculature during wakefulness could result from pathophysiological processes caused by obstructive sleep apnoea.