The MyotonPRO: A reliable tool for quantifying the viscoelastic properties of a trigger point on the infraspinatus in non-traumatic chronic shoulder pain

Exploratory Study of Biomechanical Properties and Pain Sensitivity at Back-Shu Points

OBJECTIVES

Hypersensitive acupoints in specific body areas are associated with corresponding internal or visceral disorders. Back-shu points are clinically significant for the diagnosis of visceral organ disease, according to the biomechanical characteristics of the acupoints. In this study, we assessed the biomechanical characteristics and pain sensitivities of five back-shu points linked to five visceral organs in healthy participants.

METHODS

The study included 48 volunteer participants. A myotonometry was used to assess muscle tone and muscle stiffness at five back-shu points associated with visceral organs. Pressure was monitored using a microcontroller and a force sensor. Pain sensitivity was assessed in response to deep pressure pain produced by a constant force.

RESULTS

Substantial differences in muscle tone and stiffness were observed at the five back-shu points; muscle tone was highest at BL15, whereas muscle tone and muscle stiffness were lowest at BL23. Moreover, pain sensitivity was significantly different among the acupoints; pain sensitivity was highest at BL23. There was a significant negative correlation between muscle tone and pain sensitivity.

CONCLUSIONS

We found significant differences in muscle tone, muscle stiffness, and pain sensitivity among five back-shu points associated with visceral organs, which may be attributable to anatomical variations at each point. Our findings suggest that differences at back-shu points should be considered to ensure the accurate diagnosis of visceral disease.

Evaluating the Reliability of MyotonPro in Assessing Muscle Properties: A Systematic Review of Diagnostic Test Accuracy

Background and Objectives: Muscle properties are critical for performance and injury risk, with changes occurring due to physical exertion, aging, and neurological conditions. The MyotonPro device offers a non-invasive method to comprehensively assess muscle biomechanical properties. This systematic review evaluates the reliability of MyotonPro across various muscles for diagnostic purposes. Materials and Methods: Following PRISMA guidelines, a comprehensive literature search was conducted in Medline (PubMed), Ovid (Med), Epistemonikos, Embase, Cochrane Library, Clinical trials.gov, and the WHO International Clinical Trials platform. Studies assessing the reliability of MyotonPro across different muscles were included. A methodological quality assessment was performed using established tools, and reviewers independently conducted data extraction. Statistical analysis involved summarizing intra-rater and inter-rater reliability measures across muscles. Results: A total of 48 studies assessing 31 muscles were included in the systematic review. The intra-rater and inter-rater reliability were consistently high for parameters such as frequency and stiffness in muscles of the lower and upper extremities, as well as other muscle groups. Despite methodological heterogeneity and limited data on specific parameters, MyotonPro demonstrated promising reliability for diagnostic purposes across diverse patient populations. Conclusions: The findings suggest the potential of MyotonPro in clinical assessments for accurate diagnosis, treatment planning, and monitoring of muscle properties. Further research is needed to address limitations and enhance the applicability of MyotonPro in clinical practice. Reliable muscle assessments are crucial for optimizing treatment outcomes and improving patient care in various healthcare settings.

Myofascial trigger point (MTrP) size and elasticity properties can be used to differentiate characteristics of MTrPs in lower back skeletal muscle

Myofascial trigger points (MTrPs) are localized contraction knots that develop after muscle overuse or an acute trauma. Significant work has been done to understand, diagnose, and treat MTrPs in order to improve patients suffering from their effects. However, effective non-invasive diagnostic tools are still a missing gap in both understanding and treating MTrPs. Effective treatments for patients suffering from MTrP mediated pain require a means to measure MTrP properties quantitatively and diagnostically both prior to and during intervention. Further, quantitative measurements of MTrPs are often limited by the availability of equipment and training. Here we develop ultrasound (US) based diagnostic metrics that can be used to distinguish the biophysical properties of MTrPs, and show how those metrics can be used by clinicians during patient diagnosis and treatment. We highlight the advantages and limitations of previous US-based approaches that utilize elasticity theory. To overcome these previous limitations, we use a hierarchical approach to distinguish MTrP properties by patients' reported pain and clinician measured palpation. We show how US-based measurements can characterize MTrPs with this approach. We demonstrate that MTrPs tend to be smaller, stiffer, and deeper in the muscle tissue for patients with pain compared to patients without pain. We provide evidence that more than one MTrP within a single US-image field increases the stiffness of neighboring MTrPs. Finally, we highlight a combination of metrics (depth, thickness, and stiffness) that can be used by clinicians to evaluate individual MTrPs in combination with standard clinical assessments.

Biomechanical assessment of gastrocnemii and Achilles tendon using MyotonPRO: in vivo measurements, and preliminary in situ measurements using formalin-fixed tissues

PURPOSE

This study aims to evaluate the reliability and validity of using MyotonPRO to quantify the mechanical properties of the muscle-tendon unit through in vivo measurements and preliminary in situ measurements using formalin-fixed tissues.

MATERIALS AND METHODS

The mechanical properties of gastrocnemii and the Achilles tendon of 12 healthy adults (six males and six females, 34.9 ± 5.8 years) were examined for in vivo test twice within a day and once post-24 hours using MyotonPRO, while nine human cadavers (formalin-fixed, 3 males and 6 females, 89.9 ± 5.1 years) were assessed for preliminary in situ test with identical time schedule to evaluate the within-day and inter-day reliability and validity.

RESULTS

In vivo tests had very high within-day (ICC: 0.96-0.99) and inter-day reliability (ICC: 0.83-0.96), while in situ tests (formalin-fixed tissues) showed high within-day (ICC: 0.87-0.99) and inter-day reliability (ICC: 0.76-0.98) for the results of tone and stiffness. There was no significant difference in the stiffness of the free part of the Achilles tendon between in vivo and in situ conditions. The stiffness of the lateral gastrocnemius (r = 0.55, p = 0.018), proximal part of the Achilles tendon (r = 0.56, p = 0.015), and free part of the Achilles tendon (r = 0.47, p = 0.048) before removing the skin was significantly correlated with that after removing the skin condition.

CONCLUSIONS

The findings of the current study suggest that MyotonPRO is reliable and valid for evaluating tendon stiffness both in vivo and in situ (formalin-fixed tissues).

Sensory and emotional responses to deep pressure stimulation at myofascial trigger points: a pilot study

Objective

Although manual pressure, such as that used during a massage, is often associated with pain, it can simultaneously be perceived as pleasant when applied to certain body areas. We hypothesized that stimulation of myofascial trigger points (TPs) leads to simultaneous pain and pleasure. TPs are hyperirritable points located in the taut band of the skeletal muscle.

Method

In this study, we measured the muscle tone, muscle stiffness, and pressure pain threshold of TPs and control points in the left brachioradialis muscle of 48 healthy participants. We also applied deep compression to the two points and collected subjective data on pain, pleasantness, unpleasantness, and relief.

Result

Greater muscle stiffness was observed in the TPs versus control points (t = 6.55, p < 0.001), and the pain threshold was significantly lower in the TPs (t = -6.21, p < 0.001). Unpleasantness ratings after deep compression were significantly lower in the TPs compared with control points (t = -2.68, p < 0.05). Participants experienced greater relief at the TPs compared with control points (t = 2.01, p < 0.05), although the perceived pain did not differ between the two types of points.

Conclusion

We compared the properties of TPs and control points, and found that deep compression at TPs was associated with higher muscle tone and stiffness, lower unpleasantness ratings, and higher relief ratings compared with the control points. These findings suggest that, at least for some TPs, pain and pleasantness are simultaneously elicited by deep pressure stimulation.

The Utility of Myotonometry in Musculoskeletal Rehabilitation and Human Performance Programming

Myotonometry is a relatively novel method used to quantify the biomechanical and viscoelastic properties (stiffness, compliance, tone, elasticity, creep, and mechanical relaxation) of palpable musculotendinous structures with portable mechanical devices called myotonometers. Myotonometers obtain these measures by recording the magnitude of radial tissue deformation that occurs in response to the amount of force that is perpendicularly applied to the tissue through a device's probe. Myotonometric parameters such as stiffness and compliance have repeatedly demonstrated strong correlations with force production and muscle activation. Paradoxically, individual muscle stiffness measures have been associated with both superior athletic performance and a higher incidence of injury. This indicates optimal stiffness levels may promote athletic performance, whereas too much or too little may lead to an increased risk of injury. Authors of numerous studies suggested that myotonometry may assist practitioners in the development of performance and rehabilitation programs that improve athletic performance, mitigate injury risk, guide therapeutic interventions, and optimize return-to-activity decision-making. Thus, the purpose of our narrative review was to summarize the potential utility of myotonometry as a clinical tool that assists musculoskeletal clinicians with the diagnosis, rehabilitation, and prevention of athletic injuries.

Myofascial Trigger Points therapy decreases myotonometric tone and stiffness of trapezius muscle, benefits headaches and muscle pain in migraine

BACKGROUND

Migraine is a primary headache disorder. Studies have shown that 93% of people with migraine have an increased number of active Ischemic Compression Myofascial Trigger Points (IC-MTrPs) therapy.

OBJECTIVE

To examine the effects of the IC-MTrPs therapy on: (1) mechanical properties of the upper trapezius muscle (UTM), (2) shoulder girdle and neck (SGN) muscles pain and (3) headaches characteristics in episodic migraine patients without aura.

METHODS

Thirty-one adult, female, migraine patients without aura underwent seven IC-MTrPs therapy sessions and were tested during maximally five measurement sessions (pre- and post-1'st, post-4'th, post-7'th therapy and 1-month follow-up). Myotonometric measurements of the UTM's tone, stiffness and elasticity, subjective SGN muscles pain, as well as headache's level, frequency and duration were analyzed.

RESULTS

Myotonometric tone and stiffness of the UTM significantly decreased in post-1'st, post-4'th therapy and in 1-month follow-up measurements versus pre-1'st therapy testing session. The scores for the SGN muscles' pain significantly decreased: (i) in post-4'th and post-7'th therapy versus post-1'st therapy session, and (ii) in post-7'th versus post-4'th therapy measurements. Headache's level, frequency and duration significantly decreased in post-7'th therapy versus pre-1'st therapy measurement session.

CONCLUSION

IC-MTrPs therapy resulted in a decrease of upper trapezius muscle tone and stiffness, with simultaneous alleviation of shoulder girdle and neck muscle pain and the headaches characteristics in episodic migraine patients without aura.

Quantification of the forearm muscles mechanical properties using Myotonometer: Intra- and Inter-Examiner reliability and its relation with hand grip strength

The primary objective of this study was to investigate the reliability of the myotonometer in the mechanical properties of the forearm muscles [m. extensor carpi radialis brevis (ECRB), and m. flexor carpi ulnaris (FCU)] in healthy individuals. The secondary objective was to investigate the relationship between the handgrip strength and mechanical properties of these forearm muscles. The mechanical properties (muscle tone, stiffness, and elasticity) of the ECRB and FCU were measured using the MyotonPRO device. Examiner 1 performed two sets of measurements with a time interval of 30 min to determine intra-examiner reliability. Examiner 2 performed measurements during the interval between the two sets of examiner 1. The intra- and inter-examiner reliabilities were excellent (ICC˃0.82) for muscle tone, stiffness, and elasticity of the FCU. Both intra- and inter-examiner reliability in the evaluation of ECRB muscle tone, elasticity, and stiffness was moderate to excellent (ICCs = 0.56-0.98). The muscle tone and stiffness properties of the FCU were positively correlated with the handgrip strength (p <.05). The study findings indicate that the MyotonPRO device is a reliable tool to quantify ECRB, and FCU muscles mechanical properties in healthy individuals.

Effect of osteopathic techniques on human resting muscle tone in healthy subjects using myotonometry: a factorial randomized trial

Musculoskeletal disorders (MSDs) are highly prevalent, burdensome, and putatively associated with an altered human resting muscle tone (HRMT). Osteopathic manipulative treatment (OMT) is commonly and effectively applied to treat MSDs and reputedly influences the HRMT. Arguably, OMT may modulate alterations in HRMT underlying MSDs. However, there is sparse evidence even for the effect of OMT on HRMT in healthy subjects. A 3 × 3 factorial randomised trial was performed to investigate the effect of myofascial release (MRT), muscle energy (MET), and soft tissue techniques (STT) on the HRMT of the corrugator supercilii (CS), superficial masseter (SM), and upper trapezius muscles (UT) in healthy subjects in Hamburg, Germany. Participants were randomised into three groups (1:1:1 allocation ratio) receiving treatment, according to different muscle-technique pairings, over the course of three sessions with one-week washout periods. We assessed the effect of osteopathic techniques on muscle tone (F), biomechanical (S, D), and viscoelastic properties (R, C) from baseline to follow-up (primary objective) and tested if specific muscle-technique pairs modulate the effect pre- to post-intervention (secondary objective) using the MyotonPRO (at rest). Ancillary, we investigate if these putative effects may differ between the sexes. Data were analysed using descriptive (mean, standard deviation, and quantiles) and inductive statistics (Bayesian ANOVA). 59 healthy participants were randomised into three groups and two subjects dropped out from one group (n = 20; n = 20; n = 19-2). The CS produced frequent measurement errors and was excluded from analysis. OMT significantly changed F (-0.163 [0.060]; p = 0.008), S (-3.060 [1.563]; p = 0.048), R (0.594 [0.141]; p < 0.001), and C (0.038 [0.017]; p = 0.028) but not D (0.011 [0.017]; p = 0.527). The effect was not significantly modulated by muscle-technique pairings (p > 0.05). Subgroup analysis revealed a significant sex-specific difference for F from baseline to follow-up. No adverse events were reported. OMT modified the HRMT in healthy subjects which may inform future research on MSDs. In detail, MRT, MET, and STT reduced the muscle tone (F), decreased biomechanical (S not D), and increased viscoelastic properties (R and C) of the SM and UT (CS was not measurable). However, the effect on HRMT was not modulated by muscle-technique interaction and showed sex-specific differences only for F.Trial registration German Clinical Trial Register (DRKS00020393).

Immediate Effect of Dry Needling on the Viscoelastic Properties of a Trigger Point on the Infraspinatus Muscle Measured with MyotonPRO

Purpose: This article investigates the immediate effects of a dry needling (DN) puncture on the viscoelastic properties (tone, stiffness, elasticity) of a trigger point (TP) in the infraspinatus muscle in non-traumatic chronic shoulder pain. Method: Forty-eight individuals with non-traumatic chronic shoulder pain were recruited. The presence of a TP in the infraspinatus muscle was confirmed by a standardized palpatory exam. The viscoelastic properties were measured with a MyotonPRO device at baseline (T1), immediately after DN (T2), and 30 minutes later (T3). A DN puncture was applied to the TP to obtain a local twitch response while performing the technique. Results: Analyses of variance showed significant decreases in tone ( p < 0.001) and stiffness ( p = 0.003) across time after the DN technique. Post hoc tests revealed a significant reduction in tone and stiffness from T1 to T2 ( p ≤ 0.004) and no significant changes from T2 to T3 ( p ≥ 0.10). At T3, only stiffness remained significantly lower compared to T1 ( p = 0.013). Conclusions: This study brings new insights on the immediate mechanical effect of DN on tone and stiffness of TPs. Whether these effects are associated with symptom improvement and long-term effects still needs to be verified.

Radial shock-wave therapy for frozen shoulder patients with type 2 diabetes mellitus: a pilot trial comparing two different energy levels

BACKGROUND

Extracorporeal shock-wave therapy (ESWT) is highly recommended for the management of orthopedic shoulder pathologies. Yet, the clinical relevance of the dose difference effect of radial ESWT approaches in the management of frozen shoulder patients with type 2 diabetes mellitus remains uncertain.

AIM

The aim was to examine the short-term effects of medium-and high-energy levels of radial ESWT (rESWT) in the treatment of frozen shoulder patients with type 2 diabetes mellitus.

DESIGN

Prospective clinical pilot study.

SETTING

This study was conducted in an outpatient clinic.

POPULATION

Thirty-nine patients who had frozen shoulder untreated for at least 3 months, diagnosed with type 2 diabetes mellitus for ≥3 years were included.

METHODS

The patients were randomly allocated to receive either high-energy rESWT (hrESWT), or medium-energy rESWT (mrESWT) or placebo at 8 Hz twice a week for six weeks. The primary outcome measure was pain, evaluated by the Visual Analog Scale (VAS) Score. Secondary outcome measures were function evaluated by the Shoulder Pain and Disability Index (SPADI) Score, and shoulder active range of motion (AROM). The mechanical properties of the deltoid and trapezius muscles were assessed using the MyotonPRO (Myoton AS, Tallinn, Estonia).

RESULTS

The mrESWT resulted in statistically significant reductions in night pain at 6 weeks (η<inf>p</inf>²=0.27, P=0.003). Significantly improved function (SPADI scores: -35.42±21.29 vs.-29.59±22.60; η<inf>p</inf>²=0.39, P˂0.001) was found in both hrESWT and mrESWT group by 6 weeks. Significantly higher mean shoulder AROM values were recorded for external rotation (η<inf>p</inf>²=0.53, P<0.001), and internal rotation (η<inf>p</inf>²=0.21, P=0.020), in the hrESWT group at the 6^th week. A significantly improved resting tone (η<inf>p</inf>²=0.58) and stiffness of deltoid muscle (η<inf>p</inf>²=0.62) were found in the mrESWT group (P<0.001). The trapezius muscle resting tone reduced with hrESWT (η<inf>p</inf>²=0.17, P=0.033).

CONCLUSIONS

Regardless of the energy levels, rESWT appears to be an effective therapeutic intervention for frozen shoulder patients with type 2 diabetes mellitus in the short-term results.

CLINICAL REHABILITATION IMPACT

Our results suggest that this rESWT can be a useful strategy for the rehabilitation of frozen shoulder patients with type 2 diabetes mellitus. This is the first study on dose difference effectiveness in terms of the clinical significance of rESWT which is key to transfer research evidence into practice.

Comparison of Surgeon Muscular Properties between Standard Operating Microscope and Digitally Assisted Vitreoretinal Surgery Systems

PURPOSE

To quantitatively analyze surgical ergonomics between standard operating microscope (SOM) and digitally assisted vitreoretinal surgery (DAVS) systems.

METHODS

The surgeon conducted procedures on 110 patients; 52 patients underwent a combined phacoemulsification and pars plana vitrectomy (Phaco-PPV group, 24 using SOM and 28 using DAVS), and 58 patients underwent phacoemulsification (Phaco group, 30 using SOM and 28 using DAVS). The surgeon's muscle tone and stiffness in the sternocleidomastoid (SCM) and the two positions of the upper trapezius (UT), which are 2 cm intervals along the UT muscle fibers, UT1 and UT2, were measured at preoperative, intraoperative, and postoperative time points.

RESULTS

In the Phaco-PPV group using the SOM, intraoperative muscle tone and stiffness were higher than pre- and postoperative values in the SCM (P<0.001, respectively), UT1 (P<0.001, respectively), and UT2 (P<0.001 and P<0.01, respectively). In the Phaco group using the SOM, intraoperative muscle tone and stiffness were higher than pre- and postoperative values in the SCM (P<0.001, respectively) and UT1 (P<0.001 and P<0.01, respectively). By contrast, when the surgeon used the DAVS, there were no differences in muscle properties at any measurement site or during any time point in the Phaco-PPV and Phaco groups (P>0.05).

CONCLUSIONS

This study provides quantitative measurement of retina surgeon ergonomics, suggesting that compared with a SOM, the DAVS can reduce intraoperative muscle fatigue.

Effects of dry needling on mechanical and contractile properties of the upper trapezius with latent myofascial trigger points: A randomized controlled trial

BACKGROUND

Latent trigger point (LTrP) can cause motor dysfunction and disturb normal patterns of motor recruitment.

OBJECTIVE

To analyze the effects of DN in the upper trapezius (UT) LTrP on pain and the mechanical and contractile properties of the muscle.

DESIGN

A randomized, double-blinded, parallel-group-trial.

METHODS

Fifty healthy volunteers with LTrPs in the UT were randomly divided into a DN-group (n = 26) and a Sham-DN-group (n = 24) and received one session of DN or placebo treatment. Mechanical and contractile properties of the muscle and pressure pain perception (PPP) were evaluated before treatment and in a 30min, 24 h and 72 h follow-up after treatment.

RESULTS

In the mechanical properties, the DN-group showed lower values than the Sham-DN-group for dynamic stiffness at 72 h (p = 0.04). The DN-group showed lower values for dynamic stiffness at 72 h from baseline (278.74 ± 38.40 to 261.54 ± 33.64 N/m; p = 0.01) and for tone at 72 h from 30min (16.62 ± 1.27 to 15.88 ± 1.31 Hz; p = 0.01). In the contractile properties, the DN-group showed higher values for maximal radial displacement (Dm) of the muscle belly at 72 h from baseline (5.38 ± 1.67 to 6.13 ± 1.70 mm; p = 0.04), higher values for contraction time at 30min (28.53 ± 8.80 s; p = 0.03) and lower ones at 72 h (24.74 ± 4.36 s; p = 0.04) from baseline (26.97 ± 6.63 s). The DN-group showed a decrease of PPP from baseline to 72 h after treatment (5.16 ± 1.33 to 4.02 ± 0.97 mm; p < 0.01).

CONCLUSION

The application of DN in healthy volunteers over LTrPs in the UT decreased dynamic stiffness, tone and contraction time and increased Dm at 72 h after treatment. Additionally, the PPP showed a decrease at 72 h after needling. CLINICALTRIALS.GOV: NCT04466813.

Neurophysiological and psychophysical effects of dry versus sham needling of the infraspinatus muscle in patients with chronic shoulder pain: a randomized feasibility study

BACKGROUND

Dry needling (DN) is increasingly used for treating myofascial trigger points (MTrPs) and has shown significant effects on pain and function. This study aimed to assess feasibility of conducting a randomized sham-controlled trial and to collect preliminary data on the effects of infraspinatus DN on corticospinal excitability and mechanical pain sensitivity.

METHOD

This randomized feasibility study included adults with chronic non-traumatic shoulder pain and a infraspinatus MTrP. Participants were randomized to receive real DN or sham DN in the infraspinatus MTrP. Feasibility outcomes included data pertaining to recruitment, retention of participants, completeness and safety of assessment procedures. Neurophysiological and psychophysical outcomes included corticospinal excitability and mechanical pain sensitivity measured by active motor threshold (aMT) and pressure pain threshold (PPT), respectively. They were assessed at baseline, immediately after and 24 h post-intervention.

RESULTS

Twenty-one participants were recruited over a 6-month period. Nineteen participants completed the treatment and follow-up assessment. Motor evoked potential responses were discernible in all but 1 participant. Only 1 minor adverse event related to transcranial magnetic stimulation (mild headache) affected the measurements. No DN adverse effects were recorded in both groups. An overall completeness rate of 81% was reached, with 70% completeness in the DN group and 91% in the sham group. Data analysis revealed that real DN increased corticospinal excitability (reduced aMT) 24 h post-intervention (Mdn = - 5.96% MSO, IQR = 5.17, p = 0.04) and that sham DN triggered similar responses immediately after the intervention (Mdn = - 1.93% MSO, IQR = 1.11, p = 0.03). Increased mechanical pain sensitivity (reduced PPT) was significant only in the sham group, both immediately (Mdn = - 0.44 kg/cm2, IQR = 0.49, p = 0.01) and 24 h post-intervention (Mdn = - 0.52 kg/cm2, IQR = 1.02, p = 0.02). Changes in corticospinal excitability was positively correlated with changes in mechanical pain sensitivity in the DN group, both immediately (r = 0.77, p = 0.02) and 24 h post-intervention (r = 0.75, p = 0.05).

CONCLUSION

The present study demonstrates the feasibility of quantifying the neurophysiological and psychophysical effects of DN, and provides recommendations and guidelines for future studies. Moreover, it provides preliminary evidence that DN may increase corticospinal excitability of the infraspinatus muscle in patients with chronic shoulder pain and that the relationship of neurophysiological and psychophysical effects is promising to better understand its mechanisms of action.

TRIAL REGISTRATION

NCT04316793 ; retrospectively registered November 3, 2020.

Immediate decrease of muscle biomechanical stiffness following dry needling in asymptomatic participants

BACKGROUND

Biomechanical muscle stiffness has been linked to musculoskeletal disorders. Assessing changes in muscle stiffness following DN may help elucidate a physiologic mechanism of DN. This study characterizes the effects of dry needling (DN) to the infraspinatus, erector spinae, and gastrocnemius muscles on biomechanical muscle stiffness.

METHOD

60 healthy participants were randomized into infraspinatus, erector spinae, or gastrocnemius groups. One session of DN was applied to the muscle in standardized location. Stiffness was assessed using a MyotonPRO at baseline, immediately post DN, and 24 h later. The presence of a localized twitch response (LTR) during DN was used to subgroup participants.

RESULTS

A statistically significant decrease in stiffness was observed in the gastrocnemius, the LTR gastrocnemius, and the LTR erector spinae group immediately following DN treatment. However, stiffness increased after 24 h. No significant change was found in the infraspinatus group.

CONCLUSIONS

DN may cause an immediate, yet transitory change in local muscle stiffness. It is unknown whether these effects are present in a symptomatic population or related to improvements in clinical outcomes. Future studies are necessary to determine if a decrease in biomechanical stiffness is related to improvement in symptomatic individuals.

Intra- and inter-evaluator reliability of the MyotonPRO for the assessment of the viscoelastic properties of caesarean section scar and unscarred skin

BACKGROUND

The clinical evaluation of viscoelastic properties of the Caesarean section (C-section) scar, such as stiffness and elasticity, is usually carried out using subjective scales and palpation techniques. There is currently no reliable and valid tool that objectively quantifies these properties. The MyotonPRO could fill this gap.

MATERIALS AND METHODS

Nineteen healthy women aged between 21 and 40 years with C-section scars participated in this reliability study. Two points, one on the scar and one on unscarred skin, were measured four times successively with the MyotonPRO by three independent evaluators on the same day. The intra-class correlation (ICC) coefficients were estimated using a two-factor ANOVA to determine the inter- and intra-rater reliability. The capacity of the MyotonPRO to discriminate the viscoelastic properties of the C-Section scar against unscarred skin was assessed using the Wilcoxon signed rank test.

RESULTS

The intra- and inter-rater reliability of the viscoelastic property measurements was good to excellent (ICC 0.99-1.00 and 0.87-0.98, respectively). There was no significant difference between C-section scar and unscarred skin in terms of elasticity (P = .737). Significant differences between C-section scars and unscarred skin tissue were observed for tone (P < .001), stiffness (P < .001), creep (P < .001), and mechanical stress relaxation time (P < .001).

CONCLUSION

The MyotonPRO is a reliable tool for an objective measurement of the viscoelastic properties of the C-section scar and unscarred skin. The MyotonPRO can discriminate the viscoelastic properties of the C-section scar against the unscarred skin, for tone, stiffness, creep and relaxation times, but not for elasticity.