Interexaminer reliability of the palpation of trigger points in the trunk and lower limb muscles

High Medial Longitudinal Arch of the Foot and Latent Trigger Points in Lower Limb Muscles

Background: The objective was to evaluate the prevalence of latent trigger points (LTrPs) in lower limb muscles in participants with a high medial longitudinal arch (MLA) of the foot compared to controls. Methods: Participants with a navicular drop test of 4-9 mm were included in the control group; the high MLA group included navicular drop test values of ≤4 mm. The presence of LTrPs was assessed by palpation techniques. The muscles evaluated were medial gastrocnemius (LTrP1), lateral gastrocnemius (LTrP2), soleus (LTrP1), peroneus longus, peroneus brevis, tibialis anterior, extensor digitorum longus, flexor digitorum longus, rectus femoris, vastus medialis (LTrP1 and LTrP2), and the vastus lateralis of the quadriceps (LTrP1 and LTrP2). Results: Thirty-seven participants with high MLA and thirty-seven controls were included in the study. Twenty-nine (78.4%) participants in the high MLA group had at least 1 LTrP, compared to twenty-three (62.2%) in the control group. No statistical difference (p < 0.05) was found in the total number of LTrPs between groups (4.46 ± 3.78 vs. 3.24 ± 3.85). There were more participants (p < 0.05) with LTrPs in the tibialis anterior, extensor digitorum longus, and vastus lateralis (LTrP1 and LTrP2) in the high MLA group than in the control group. Conclusion: Although no differences were found in the number of total LTrPs between groups, the prevalence was statistically significantly higher in the tibialis anterior, extensor digitorum longus, and vastus lateralis of the participants with high MLA of the foot.

Identification of Myofascial Trigger Point Using the Combination of Texture Analysis in B-Mode Ultrasound with Machine Learning Classifiers

Myofascial pain syndrome is a chronic pain disorder characterized by myofascial trigger points (MTrPs). Quantitative ultrasound (US) techniques can be used to discriminate MTrPs from healthy muscle. In this study, 90 B-mode US images of upper trapezius muscles were collected from 63 participants (left and/or right side(s)). Four texture feature approaches (individually and a combination of them) were employed that focused on identifying spots, and edges were used to explore the discrimination between the three groups: active MTrPs (n = 30), latent MTrPs (n = 30), and healthy muscle (n = 30). Machine learning (ML) and one-way analysis of variance were used to investigate the discrimination ability of the different approaches. Statistically significant results were seen in almost all examined features for each texture feature approach, but, in contrast, ML techniques struggled to produce robust discrimination. The ML techniques showed that two texture features (i.e., correlation and mean) within the combination of texture features were most important in classifying the three groups. This discrepancy between traditional statistical analysis and ML techniques prompts the need for further investigation of texture-based approaches in US for the discrimination of MTrPs.

Myofascial Trigger Point Identification in B-Mode Ultrasound: Texture Analysis Versus a Convolutional Neural Network Approach

OBJECTIVE

Myofascial pain syndrome (MPS) is one of the most common causes of chronic pain and affects a large portion of patients seen in specialty pain centers as well as primary care clinics. Diagnosis of MPS relies heavily on a clinician's ability to identify the presence of a myofascial trigger point (MTrP). Ultrasound can help, but requires the user to be experienced in ultrasound. Thus, this study investigates the use of texture features and deep learning strategies for the automatic identification of muscle with MTrPs (i.e., active and latent MTrPs) from normal (i.e., no MTrP) muscle.

METHODS

Participants (n = 201) were recruited from Toronto Rehabilitation Institute, and ultrasound videos of their trapezius muscles were acquired. This new data set consists of 1344 images (248 active, 120 latent, 976 normal) collected from these videos. For texture analysis, several features were investigated with varying parameters (i.e., region of interest size, feature type and pixel pair relationships). Convolutional neural networks (CNN) were also applied to observe the performance of deep learning approaches. Performance was evaluated based on the classification accuracy, micro F1-score, sensitivity, specificity, positive predictive value and negative predictive value.

RESULTS

The best CNN approach was able to differentiate between muscles with and without MTrPs better than the best texture feature approach, with F1-scores of 0.7299 and 0.7135, respectively.

CONCLUSION

The results of this study reveal the challenges associated with MTrP identification and the potential and shortcomings of CNN and radiomics approaches in detail.

Associations Between Gluteus Medius Trigger Points With Hip Passive Range of Movement and Muscle Strength in Adults With Chronic Nonspecific Low Back Pain: A Cross-Sectional Study

OBJECTIVE

The purpose of this study was to investigate whether there is a relationship between gluteus medius trigger points with hip passive range of motion and hip muscle strength in people with chronic nonspecific low back pain (LBP).

METHODS

This was a cross-sectional, blinded study that took place in 2 rural communities in New Zealand. Assessments were carried out in physiotherapy clinics in these towns. A total of 42 participants over 18 years old experiencing chronic nonspecific LBP were recruited. After meeting inclusion criteria, participants completed the following 3 questionnaires: Numerical Pain Rating Scale, Oswestry Disability Index, and Tampa Scale of Kinesiophobia. The primary researcher (a physiotherapist) assessed each participant's bilateral hip passive range of movement (using an inclinometer) and muscle strength (using a dynamometer). Following this, a blinded trigger point assessor examined the gluteus medius muscles for the presence of active and latent trigger points.

RESULTS

General linear modeling using univariate analysis revealed that there was a positive association between hip strength and trigger point status (P =.03 left internal rotation, P =.04 right internal rotation, and P =.02 right abduction). Participants with no trigger points showed higher strength values (eg, right internal rotation standard error: 0.64), and those with trigger points showed lower strength. Overall, muscles exhibiting latent trigger points were the weakest (eg, right internal rotation standard error: 0.67).

CONCLUSION

The presence of active or latent gluteus medius trigger points was associated with hip weakness in adults with chronic nonspecific LBP. There was no association between gluteus medius trigger points and hip passive range of movement.

A macroscopic anatomical study of the appropriate palpation zone of the gluteus medius muscle

[Purpose] Few previous studies have delimitated the palpation zone of the gluteus medius muscle with a focus on its fiber bundles. The purpose of this study was to clarify the morphological characteristics of the gluteus medius muscle using an anatomical approach, and to define its proper palpation zone. [Participants and Methods] In this study, we evaluated thirteen halves of the pelvic region in seven formalin-fixed cadavers. We identified the borders between the iliotibial band and gluteus medius muscle, and between the gluteus medius and gluteus maximus muscles, on the iliac crest. Furthermore, we quantified the border points of the gluteus medius’ fiber bundles and observed its anatomical and morphological characteristics. [Results] We identified two fiber bundles in the gluteus medius muscle, an anterior and a posterior fiber bundle, and detected that a portion of the posterior fibers was located subcutaneously. [Conclusion] We propose that the region where the posterior fibers of the gluteus medius muscle are located subcutaneously is an appropriate zone for the palpation of this muscle.

Trigger Point Injections

Myofascial pain and myofascial pain syndromes are among some of the most common acute and chronic pain conditions. Many interventional procedures can be performed in both an acute and chronic pain setting to address myofascial pain syndromes. Trigger point injections can be performed with or without imaging guidance such as fluoroscopy and ultrasound; however, the use of imaging in years past has been recommended to improve patient outcome and safety. Injections can be performed using no injectate (dry needling), or can involve the administration of local anesthetics, botulinum toxin, or corticosteroids.

The Effect of Dry Needling on Pain, Range of Motion of Ankle Joint, and Ultrasonographic Changes of Plantar Fascia in Patients With Plantar Fasciitis

CONTEXT

Plantar fasciitis (PF) is a common and devastating disease. Despite different treatments, there is no clear evidence for the effect of these treatments on PF. One of the therapy methods used in physiotherapy is dry needling (DN). So the purpose of this study is to investigate the effect of DN on the pain and range of motion of the ankle joint and plantar fascia thickness in subjects with PF who are suffering from the trigger points of the gastrocnemius and soleus muscles.

METHODS

In this study, 20 volunteer females with PF were randomly assigned into DN treatment and control groups. Measurements were range of motion in dorsiflexion and plantar flexion, plantar fascia thickness, and visual analog scale measured before, immediately, and 1 month after the end of the intervention in both groups.

RESULTS

There were significant differences in the plantar fascia thickness and visual analog scale between the 2 groups. Plantar fascia thickness (P = .016) and visual analog scale (P = .03) significantly decreased in the treatment group. However, there was no significant difference in plantar flexion (P = .582) and dorsiflexion range of motion (P = .173) between groups.

CONCLUSION

The result of this study showed that DN can reduce pain and plantar fascia thickness in women with PF who are suffering from trigger points of the gastrocnemius and soleus muscles.

LEVEL OF EVIDENCE

Level 1, randomized controlled trial.

Reliability and validity of manual palpation for the assessment of patients with low back pain: a systematic and critical review

BACKGROUND

Static or motion manual palpation of the low back is commonly used to assess pain location and reproduction in low back pain (LBP) patients. The purpose of this study is to review the reliability and validity of manual palpation used for the assessment of LBP in adults.

METHOD

We systematically searched five databases from 2000 to 2019. We critically appraised internal validity of studies using QAREL and QUADAS-2 instruments. We stratified results using best-evidence synthesis. Validity studies were classified according to Sackett and Haynes.

RESULTS

We identified 2023 eligible articles, of which 14 were low risk of bias. Evidence suggests that reliability of soft tissue structures palpation is inconsistent, and reliability of bony structures and joint mobility palpation is poor. We found preliminary evidence that gluteal muscle palpation for tenderness may be valid in differentiating LBP patients with and without radiculopathy.

CONCLUSION

Reliability of manual palpation tests in the assessment of LBP patients varies greatly. This is problematic because these tests are commonly used by manual therapists and clinicians. Little is known about the validity of these tests; therefore, their clinical utility is uncertain. High quality validity studies are needed to inform the clinical use of manual palpation tests.

Re-Examining Myofascial Pain Syndrome: Toward Biomarker Development and Mechanism-Based Diagnostic Criteria

PURPOSE OF REVIEW

We discuss the need for a mechanism-based diagnostic framework with a focus on the development of objective measures (e.g., biomarkers) that can potentially be added to the diagnostic criteria of the syndrome. Potential biomarkers are discussed in relation to current knowledge on the pathophysiology of myofascial pain syndrome (MPS), including alterations in redox status, inflammation, and the myofascial trigger point (MTrP) biochemical milieu, as well as imaging and neurophysiological outcomes. Finally, we discuss the long-term goal of conducting a Delphi survey, to assess the influence of putative MPS biomarkers on clinician opinion, in order to ultimately develop new criteria for the diagnosis of MPS.

RECENT FINDINGS

Myofascial pain syndrome (MPS) is a prevalent healthcare condition associated with muscle weakness, impaired mood, and reduced quality of life. MPS is characterized by the presence of myofascial trigger points (MTrPs): stiff and discrete nodules located within taut bands of skeletal muscle that are painful upon palpation. However, physical examination of MTrPs often yields inconsistent results, and there is no gold standard by which to diagnose MPS. The current MPS diagnostic paradigm has an inherent subjectivity and the absence of correlation with the underlying pathophysiology. Recent advancements in ultrasound imaging, systemic biomarkers, MTrP-specific biomarkers, and the assessment of dysfunction in the somatosensorial system may all contribute to improved diagnostic effectiveness of MPS.

Reliability of trigger points evaluation in the lower leg muscles

BACKGROUND

Myofascial trigger point diagnosis is a clinical palpatory skill dependent on the patient's subjective response. The inter- and intra-rater reliability of trigger point physical evaluation in the lower leg muscles has rarely been reported. Previous reliability studies suffered from the Kappa paradox.

OBJECTIVE

To evaluate the inter- and intra-rater reliability of trigger point recognition in the lower leg muscles implying a specific method to overcome the 1st Kappa paradox.

DESIGN

A reliability study with pre-second examiner exclusion to correct prevalence index.

SETTING

Physical therapy outpatient clinic, Beer-Sheva, Israel.

SUBJECTS

86 soldiers aged 18-30 referred for physical therapy with a diagnosis of musculoskeletal pain consented to take part in this study. 26 were excluded for lacking trigger points, leaving 60 subjects for analysis (31 women, 29 men).

METHODS

Both legs were evaluated, and the results were analyzed separately for symptomatic (N = 87) and asymptomatic legs (N = 31).Each subject was evaluated three times, twice by one examiner, and once by a second examiner. Dichotomous findings including palpable taut-band, tenderness, referred pain, and relevance of referred pain were recorded.

RESULTS

Inter-rater reliability for active trigger points ranged from 0.49 to 0.75 (median: 0.52) and intra-rater reliability ranged from 0.41 to 0.84 (median: 0.65) and. For total trigger points intra-rater reliability ranged from 0.52 to 0.79 (median: 0.67), and inter-rater reliability ranged from 0.44 to 0.77 (median: 0.66).

CONCLUSIONS

Physical examination is a reliable method of trigger point evaluation in lower leg muscles, and it can be used as a diagnostic method for trigger point evaluation.

Comparison of the prevalence of myofascial trigger points of muscles acting on knee between patients with moderate degree of knee osteoarthritis and healthy matched people

INTRODUCTION

Trigger points have been implicated in the development of several musculoskeletal disorders. Trigger points harbored in lower limb muscles might represent a ubiquitous source of pain in patients with knee osteoarthritis (OA). This study was carried out to evaluate the prevalence of Myofascial Trigger Points (MTrPs) in muscles acting on the knee in patients with OA.

METHODS

Thirty-seven patients aged at least 55 years old with a moderate degree of OA (grade III of Kellgren and Lawrence scale) were recruited. Thirty asymptomatic people, matched on age and body mass index, were considered as the control group. Ten muscles acting on the knee joint were selected. Taut bands were also identified using a skin rolling method. A pressure of 3 kg/cm² was used to identify myofascial trigger points in all muscles except the popliteus (8 kg/cm²).

RESULTS

Chi-square was performed to compare the prevalence of trigger points between the groups. The McNemar test was administered to compare the prevalence of trigger points in the right and left sides of participants. Prevalence of the trigger points was significantly higher in patients with knee OA compared with asymptomatic people in all muscles except for right (p = 0.17) and left (p = 0.41) rectus femoris, right (p = 0.61) and left (p = 0.22) sartorius and left biceps femoris (p = 0.08). Comparison of the prevalence of MTrPs bilaterally revealed that only the right and left sartorius differed significantly (p = 0.008).

CONCLUSIONS

The prevalence of MTrPs in the muscles acting on the knee joint is higher in patients with a moderate degree of knee OA compared with asymptomatic subjects.

Accuracy of rib palpation for dry needling of deep periscapular musculature, measured with ultrasound

INTRODUCTION

Dry needling of the periscapular musculature is a procedure commonly performed by physical therapists. Needling of the deep musculature may be challenging, and use of a thoracic rib as a "backstop" is often applied to prevent inadvertent puncture of the pleura. The aim of this study was to: 1) To examine the accuracy rate of experienced physical therapists in identifying a mid-scapular thoracic rib using palpation, 2) to understand patient characteristics that affect the accuracy rate, and 3) to examine if therapist confidence levels were associated with palpatory accuracy.

METHODS

Two experienced physical therapists attempted to palpate a thoracic rib in the mid-scapular region of healthy participants (n = 101 subjects, 202 ribs), and self-reported their level of confidence in an accurate palpation. Their accuracy was verified with ultrasonography.

RESULTS

The two physical therapists were accurate on 73.3% of palpations and did not differ in accuracy (72.0% vs. 75.0%, p = 0.747). The only ultrasonographic or subject characteristic measurement that correlated with improved accuracy was a reduced muscle thickness (p = 0.032). Therapists' self-reported confidence levels did not correlate to actual accuracy (p = 0.153).

DISCUSSION

Physical therapists should be aware that palpation of a thoracic rib may not be as accurate as it may seem. The greater thickness of muscle in the area reduces the accuracy of accurate palpation.

CONCLUSION

Dry needling of the periscapular muscles should be done with caution if using a rib as a "blocking" technique.

MRI in migraineurs: are there abnormalities in the area where the myofascial trigger points are palpable and in volume measurements?

INTRODUCTION

Patients with migraine may present a higher quantity of myofascial trigger points (MTrP) and alterations in the cervical muscles when compared to non-migraineurs. The magnetic resonance imaging (MRI) is a robust method for the study of human soft tissues and could be useful to investigate these points.

OBJECTIVES

To identify the presence of MTrP in the descending fibers of the trapezius muscle in women with migraine and to quantify the muscle volume by MRI, correlating it with the headache characteristics.

METHODS

A cross-sectional analytic study was conducted among 14 women, eight in migraine group, and six in without migraine group. The presence of MTrP was evaluated using Simons' criteria, and linolenic acid capsules subsequently marked the areas. MRI was performed with 1.5T, T1-weighted sequence, and T2 in the axial, sagittal, and coronal planes. The T1-weighted sequences were performed with and without gadolinium contrast.

RESULTS

The T1-weighted image analysis with and without gadolinium did not show any signal alteration in the MTrP areas in both groups. The migraine group presented more MTrP in the trapezius muscle (MD [95%CI] = 1[1; 3]; MD [95%CI] = 1[0; 2] right and left side, respectively), and a smaller muscle volume (MD [95%CI] = -198.1[-338.7;-25.6], MD [95%CI] = -149.9[-325.05;-0.13] right and left side, respectively) than non-migraineurs. The migraine frequency presented a negative strong correlation with the trapezius volumes (r = -0.812; p = 0.014).

CONCLUSION

Migraineurs present more MTrP and a smaller muscle volume than non-migraineurs. The trapezius volume is negatively correlated with migraine frequency. MRI is not a suitable outcome measure for assessing MTrP.

Local heating of trigger points reduces neck and plantar fascia pain

BACKGROUND

Heating the skin and muscles is a commonly accepted method of pain relief and a modality to increase relaxation in muscles and increase tissue blood flow.

OBJECTIVE

The purpose of the present study was to examine the effect of local heat applied to trigger points and to determine if there was pain relief in the neck and plantar fascia.

METHODS

Forty adults were divided into 2 different groups according to their pain; twenty subjects had plantar foot pain and the other 20 had nonspecific neck pain. The 20 subjects in each group were randomly subdivided into a heat and a sham group. Sensitivity to pressure was measured with an algometer. A stopwatch was given to the subject and started when either the heat patch or placebo was applied. Heat cells were applied at trigger points on the pain area.

RESULTS

Subjective pain significantly decreased in both sham and heat group patients with neck pain (p< 0.05), however, the change was greater in the heat group and there was a significant difference between the heat and sham groups (p= 0.002, d= 0.81). For the plantar pain group, a significant decrease in subjective pain was found in the heat group but not in the sham group. Pressure pain threshold significantly decreased in the heat group patients both with neck and plantar pain but for the sham group there was an increase in the pressure after sham treatment. Pain relief during the intervention was also significantly different between the heat and sham group in both patients with neck and plantar pain.

CONCLUSION

The effect of local heat on trigger points of the body on pain relief was significantly better in the heat groups than in the sham groups. This finding is significant because using heat on trigger points could be an alternative to dry needling performed by healthcare professionals. This modality can be alternative for home use and avoids opioids.

Myofascial pain syndrome and trigger points: evaluation and treatment in patients with musculoskeletal pain

PURPOSE OF REVIEW

Myofascial pain syndrome is a chronic pain condition characterized by the presence of myofascial trigger point, a hyperirritable painful spot involving a limited number of muscle fibers. The literature suggest that myofascial trigger points should be considered peripheral pain generators and this critical review will summarize recent findings concerning the clinical evaluation and the treatment of myofascial trigger points.

RECENT FINDINGS

The clinical features of myofascial trigger points and their contribution to the patient pain and disability have been detailed in several recent studies, which support the clinical relevance of the condition. Recent studies reported that manual palpation to identify MTrPs has good reliability, although some limitations are intrinsic to the diagnostic criteria. During the last decade, a plethora of treatments have been proposed and positive effects on pain and function demonstrated.

SUMMARY

The myofascial trigger point phenomenon has good face validity and is clinically relevant. Clinicians are encouraged to consider the contribution of myofascial trigger points to the patient's pain and disability through a careful medical history and a specific manual examination. Patients with myofascial trigger points will benefit from a multimodal treatment plan including dry needling and manual therapy techniques. Internal and external validity of research within the field must be improved.

The Interexaminer Reproducibility and Prevalence of Lumbar and Gluteal Myofascial Trigger Points in Patients With Radiating Low Back Pain

Objective

To determine the interexaminer reproducibility for judging the presence, number, and location of leg-pain referring myofascial trigger points, and their prevalence in patients with low back pain with and without concomitant leg pain referral.

Design

An interexaminer reproducibility study.

Setting

An outpatient public Hospital Spine Centre in Southern Denmark.

Participants

Examiners: experienced examiners (N=2), a chiropractor and a physiotherapist, respectively. Subjects: a case mix of patients with low back pain (N=32) with and without leg pain referral.

Interventions

A standardized palpation examination protocol of 4 bilateral lumbosacral muscles performed by each examiner.

Main Outcome Measures

Reproducibility on presence (measured in Cohen’s κ), number (difference and limits of agreement), location (distance between matching marks placed by examiners), and prevalence of myofascial trigger points.

Results

Kappa values of the examined muscles were as follows: quadratus lumborum (κ=0.42), gluteus medius (κ=0.83), gluteus minimus (κ=0.74), and piriformis (κ=0.62), with a mean of all examined muscles of kappa=0.66, assessed as substantial agreement. The mean difference in number of trigger points was 0.8, with limits of agreement ranging from −6.4 to 4.9. Mean distance between trigger point locations was 12.9 mm, with 57% only being identified by a single examiner. The prevalence of trigger points was 82.7%, highest in the gluteal region of the painful side.

Conclusions

Inadequate standardization and multiple trigger point sites complicate interexaminer reproducibility on location and number of patients with low back pain and leg pain referral. Nevertheless, substantial interexaminer reproducibility for the trigger point presence appears achievable. Implemented routinely, this relatively simple clinical evaluation procedure could meaningfully enhance diagnostic triage and eventual management.

Inter and Intra Operator Reliability of Motor and Palpation Evaluation in Fascial Manipulation in individuals with coxarthrosis

OBJECTIVE

An inter and intra rater reliability (INTERR and INTRAR) study was designed.

METHODS

71 subjects, with primary hip coxarthrosis, were included and randomly divided in a study group (SG= 36) and a control group (CG= 35) to assess the efficacy of the Fascial Manipulation® (FM®) method. The primary objective was the assessment of INTERR and INTRAR about movement verification (MV) and palpation verification (PV) of FM® performed by two physiotherapists (PtA and PtB). The secondary objective was evaluate the efficacy of FM® through MV, PV and pain score. Pain was assessed using the Numeric Rating Scale (NRS). SG received three weekly sessions of FM® byPtA. PtB re-evaluated all the subjects at the end of the study.

RESULTS

Results of the INTERR analysis showed for SG: MV (ICC= 0.92, k= 72.7%); PV (ICC= 0.91, k= 75.7%). For CG : MV (ICC= 0.95, k= 84.2%); PV (ICC= 0.90, k= 75%). Results of the INTRAR analysis for SG reported: MV (ICC= 0.82, k= 74,8%); PV (ICC= 0.60, k= 46.8%); for CG: MV (ICC= 0.93, k= 78.7%); PV (ICC= 0.84, k= 53.3%). Statistical significance were reported in NRS (p = 0.001), MV (p = 0.0003) and PV (p < 0.0001) with better results for SG using "Intention To Treat" method.

DISCUSSION

This study demonstrates that FM® assessment procedures have a high reliability even if applied by practitioners with basic experience. Furthermore FM® treatment can improve pain and ROM in individuals with primary coxarthrosis.

Feasibility of a Support Vector Machine Classifier for Myofascial Pain Syndrome: Diagnostic Case-Control Study

OBJECTIVES

Myofascial pain syndrome (MPS) is the most common cause of chronic pain worldwide. The diagnosis of MPS is subjective, which has created a need for a robust quantitative method of diagnosing MPS. We propose that using a support vector machine (SVM) along with ultrasound (US) texture features can differentiate between healthy and MPS-affected skeletal muscle.

METHODS

B-mode US video data were collected in the upper trapezius muscle of healthy (29) participants and patients with active (21) and latent (19) MPS, using an acquisition method outlined in previous works. Regions of interest were extracted and filtered to obtain a unique set of 917 images where texture features were extracted from each region of interest to characterize each image. These texture features were then used to train 4 separate binary SVM classifiers using nested cross-validation to implement feature selection and hyperparameter tuning. The performance of each kernel was estimated on the data and validated through testing on a final holdout set.

RESULTS

The radial basis function kernel classifier had the greatest Matthews correlation coefficient performance estimate of 0.627 ± 0.073 (mean ± SD) along with the largest area under the curve of 91.0% ± 3.0%. The final holdout test for the radial basis function classifier resulted in 86.96 accuracy, a Matthews correlation coefficient of 0.724, 88% sensitivity, and 86% specificity, validating our earlier performance estimates.

CONCLUSIONS

We have demonstrated that specific US texture features that have been used in other computer-aided diagnostic literature are feasible to use for the classification of healthy and MPS muscle using a binary SVM classifier.

The prevalence of myofascial trigger points in hip and thigh areas in anterior knee pain patients

BACKGROUND

Anterior knee pain (AKP) is a widespread problem among young athletes and soldiers. There are many theories on the etiology of AKP but there is little reference to myofascial trigger points (MTrPs) as a possible contributor.

AIM

To evaluate the association between AKP and prevalence of active and latent MTrPs in the hip and thigh muscles in soldiers.

METHODS

A cross-sectional study was conducted in the Beer-Sheva military outpatient physical therapy clinic. Subjects were 42 men and 23 women referred for physical therapy, 33 with a diagnosis of AKP (cases) and 32 with upper limb complaints (without AKP, controls). All subjects underwent physical evaluation by an examiner blinded to their identity and medical condition. The following muscles were assessed bilaterally for active or latent MTrPs: rectus femoris (proximal), vastus medialis (middle and distal), vastus lateralis (middle and distal) and gluteus medius (anterior, posterior and distal).

RESULTS

In six out of eight areas, the cases had a higher prevalence of total active and latent MTrPs than the controls. When summarizing MTrPs by muscle, cases had significantly more MTrPs than controls in each muscle. The largest difference was found in vastus medialis and vastus lateralis; nearly half of the cases had MTrPs in these muscles.

CONCLUSIONS

Subjects with AKP have a greater prevalence of MTrPs in their hip and thigh muscles than controls, indicating an association between MTrPs and AKP. Further research is necessary to determine whether MTrPs are the cause or the consequence of AKP.

Change in muscle hardness after trigger point injection and physiotherapy for myofascial pain syndrome

Assessment and treatment of masticatory myofascial pain syndrome (MPS) are not standardized and remain controversial. We examined whether muscle hardness was useful for evaluating masticatory MPS and analyzed the effectiveness of treatments such as stretching and massage (SM) and trigger point injection (TPI). Twenty healthy volunteers and 20 MPS patients were enrolled. MPS patients were divided into TPI and SM treatment groups. Hardness of masticatory muscle with a taut band (TB) and change in hardness were evaluated after SM and TPI treatments. Hardness values were significantly higher in muscle including a TB (TB point) than in the muscle of healthy controls. Visual analogue scale scores were significantly lower after SM and TPI treatments, and hardness of the TB point was significantly lower after SM but not after TPI. These results suggest that measurement of muscle hardness, including the TB, is useful for evaluating masticatory MPS. However, TPI analgesia might not be caused by change in muscle hardness. The mechanisms underlying the effects of SM and TPI on reducing pain in MPS may differ and thus warrant further research.

Superficial Dry Needling and Active Stretching in the Treatment of Myofascial Pain – a Randomised Controlled Trial

A pragmatic, single blind, randomised, controlled trial was conducted to test the hypothesis that superficial dry needling (SDN) together with active stretching is more effective than stretching alone, or no treatment, in deactivating trigger points (TrPs) and reducing myofascial pain.

Forty patients with musculoskeletal pain, referred by GPs for physiotherapy, fulfilled inclusion / exclusion criteria for active TrPs. Subjects were randomised into three groups: group 1 (n=14) received superficial dry needling (SDN) and active stretching exercises (G1); group 2 (n=13) received stretching exercises alone (G2); and group 3 (n=13) were no treatment controls (G3). During the three-week intervention period for G1 and G2, the number of treatments varied according to the severity of the condition and subject/clinician availability. Assessment was carried out pre-intervention (M1), post-intervention (M2), and at a three-week follow up (M3). Outcome measures were the Short Form McGill Pain Questionnaire (SFMPQ) and Pressure Pain Threshold (PPT) of the primary TrP, using a Fischer algometer. Ninety-one per cent of assessments were blind to grouping.

At M2 there were no significant inter-group differences, but at M3, G1 demonstrated significantly improved SFMPQ versus G3 (p=0.043) and significantly improved PPT versus G2 (p=0.011). There were no differences between G2 and G3. The mean PPT and SFMPQ scores correlated significantly in G1 only, though no significant inter-group differences were demonstrated. Numbers of patients requiring further treatment following the trial were: 6 (G1); 12 (G2); 9 (G3). Conclusion: SDN followed by active stretching is more effective than stretching alone in deactivating TrPs (reducing their sensitivity to pressure), and more effective than no treatment in reducing subjective pain. Stretching without prior deactivation may increase TrP sensitivity.

Simultaneous acquisition of magnetic resonance elastography of the supraspinatus and the trapezius muscles

We developed a Magnetic Resonance elastography (MRE) technique using a conventional magnetic resonance imaging (MRI), which allows a simultaneous elastography of the supraspinatus and trapezius muscles, by designing a new wave transducer (vibration pad) and optimizing the mechanical vibration frequency. Five healthy volunteers underwent an MRE. In order to transmit the mechanical vibration (pneumatic vibration) to the supraspinatus and trapezius muscles, a new vibration pad was designed using a three-dimensional (3D) printer. The vibration pad was placed on the skin 2 cm medial and 2 cm cephalad the deltoid tubercle. MRE acquisition was performed with a multi-slice gradient-echo type multi-echo MR sequence, which allows MREs even in a conventional MRI; two oblique axial images of the supraspinatus and trapezius muscles were obtained simultaneously. Vibration frequencies were set at 50-150 Hz, with a 25 Hz step. Wave image quality in each frequency was analyzed using a phase-to-noise ratio (PNR) and clarity of propagating wave that was assessed by two readers qualitatively. In the supraspinatus muscle, the wave images were of good quality especially at frequencies >75 Hz. In the trapezius muscle, the wave images were of better quality at low frequencies (50 and 75 Hz) compared with high frequencies (100-150 Hz). The PNR of both muscles were higher at low frequencies. The mean stiffness in the trapezius muscle (7.26 ± 2.13 kPa at 75 Hz) was larger than those in the supraspinatus muscle (4.16 ± 0.50 kPa at 75 Hz). The results demonstrated that our MRE technique allows simultaneous assessment of the stiffness in the supraspinatus and trapezius muscles using a conventional MRI, and that optimal vibration frequency for simultaneous MRE of these muscles is 75 Hz. This technique provides a new means for early detection of abnormality in the shoulder.

A critical overview of the current myofascial pain literature - July 2018

In the current issue of this clinical overview, we are pleased to include several basic research studies ranging from the differentiation of radicular and non-radicular low back pain based on the presence of trigger points (TrPs) to the role of TrPs in patients with osteoarthritis, the diagnostic criteria of TrP, the accurate placement of needles in the piriformis muscle with dry needling (DN), and the reliability of TrP identification, among others. As usual, there are many new DN studies, but also several review papers, and manual TrP research. Contributing authors come from as many as 15 different countries!

The effects of dry needling and radial extracorporeal shockwave therapy on latent trigger point sensitivity in the quadriceps: A randomised control pilot study

OBJECTIVES

Latent myofascial trigger points (TrP) can alter joint kinematics, reduce strength and alter activation patterns, affecting athletic performance. TrP sensitivity can be measured with the pressure pain threshold (PPT). Dry needling (DN) has been used to treat latent TrPs, but may cause post-needling soreness. Radial extracorporeal shockwave therapy (rESWT) could be used as an alternative to DN during heavy training or competition.

METHODS

After baseline measures, 21 recreational athletes were split into three groups: DN, rESWT or control group, and were treated for three sessions in one week. Follow-up outcome sessions were conducted two to four and seven days after the last treatment. TrP sensitivity was measured using the PPT.

RESULTS

There was a groupXtime interaction for the PPT (p < 0.05). After a decrease in PPT during treating, there was a significant increase (p < 0.05) in PPT for the DN group (12.92%). The rESWT group also significantly (p < 0.05) increased (13.26%), but did not show any post-treatment soreness during the treatment phase. There was no difference in the PPT in the control group during any session.

CONCLUSION

DN is effective for increasing PPT of latent TrPs, but can be associated with post-treatment soreness. rESWT is as effective, but without the post-treatment soreness. Future studies should include treating multiple TrPs in the lower kinetic chain as well as measuring muscle activation and joint function. Furthermore, consideration for the current training load and up-coming competition is needed. Optimum timing and longer follow-up periods of such interventions should be explored.

LEVEL OF EVIDENCE

2b.

SUMMARY

Treating latent TrPs in the lower kinetic chain may improve muscle activation. Unlike DN, rESWT does not cause post- treatment soreness. Consideration of training load and up-coming competition is needed to deliver the optimum treatment strategy for athletes with latent TrPs.

Quantitative Ultrasound Assessment of Myofascial Pain Syndrome Affecting the Trapezius: A Reliability Study

OBJECTIVES

Myofascial pain syndrome is one of the most common causes of chronic pain and is highlighted by the presence of myofascial trigger points. The current practice of diagnosing myofascial pain syndrome among clinicians involves manual detection of myofascial trigger points, which can be inconsistent. However, the detection process can be strengthened with the assistance of ultrasound (US). Therefore, this study aimed to characterize the upper trapezius by using quantitative techniques in healthy asymptomatic individuals with neck pain.

METHODS

Study participants were recruited on the basis of the inclusion and exclusion criteria established, and US images of the trapezius, along the axial and longitudinal orientations, were obtained. Each set was obtained by 2 investigators: experienced and inexperienced personnel.

RESULTS

Fifteen participants were recruited. The mean gray scale US echo intensity distribution obtained was 41.9. A paired t test of the global mean echo intensity value obtained for each image from the US operators did not show any significant difference (P = .77). A t test was performed, comparing the echo intensity of the group of patients with neck pain and healthy control participants, and the difference was found to be significant (P = .052). The median blob area was 2.71. The quartile range for the blob area was 1.72 for the 25th percentile to 4.90 for the 75th percentile.

CONCLUSIONS

This study demonstrated that quantitative analysis of the echo intensity of US images can provide important information. However, further research is necessary to explore the relationships among sex, age, blob area, count, body mass index, regional anatomy, and extent of training or exercise of the particular muscle.

A Multimodal Approach for Myofascial Pain Syndrome: A Prospective Study

OBJECTIVE

The purpose of this study was to analyze pain intensity in patients with myofascial pain syndrome (MPS) following a multimodal rehabilitation protocol.

METHODS

A prospective study was carried out following the Template for Intervention Description and Replication criteria. Patients were recruited from the rehabilitation unit of a university hospital in Spain between 2009 and 2013. Patients were included if they had a medical diagnosis of MPS in any of the following regions: cervicobrachial (n = 102), lumbosacral (n = 30), elbow (n = 14), ankle and foot (n = 10), and temporomandibular jaw (n = 1). The multimodal rehabilitation protocol included myofascial trigger point dry needling, spray and stretching, Kinesio taping, eccentric exercise, and patient education. The protocol was applied for 4 weeks (5 sessions) for the active and/or latent myofascial trigger points in each body region. Pain intensity was measured by using the visual analog scale (VAS) immediately before beginning of the study and 1 week after completion of the protocol.

RESULTS

The study sample comprised 150 patients (mean ± standard deviation age, 51.5 ± 1.19 years). Statistically significant differences were obtained for reduction in pain intensity (4 ± 2.03; P = .002). Clinically relevant reductions (VAS ≥30 mm; P < .001) were obtained in 78.7% of the interventions. Four treatment sessions reduced the VAS score by 10 mm in 83.55% of the sample. There were no statistically significant differences (P = .064) for reduction in pain intensity in the different body regions.

CONCLUSIONS

A multimodal rehabilitation protocol showed clinically relevant differences in the reduction in pain intensity in different body regions in patients with MPS.

Novel method to measure active myofascial trigger point stiffness using ultrasound imaging

INTRODUCTION

Myofascial trigger points (MTrPs) are one of the most common and important causes of musculoskeletal pain. Ultrasound is a useful modality in examining musculoskeletal disorders. By applying compressive stress and observing changes in ultrasound images, the elastic modulus (Young's modulus) can be calculated. Our objective was to develop a novel method to distinguish MTrPs from normal tissues.

METHODS

A total of 29 subjects with MTrP in the sternocleidomastoid muscle were assessed. A force gauge was attached to a transducer to obtain stress levels. To obtain strain, images were recorded in both with stress and without stress states. By dividing the stress level by the measured strain, the elastic modulus was determined.

RESULTS

Elastic modulus in MTrPs and the normal part of the muscle were measured to be 13379.57 ± 1069.75Pa and 7078.24 ± 482.92Pa, respectively (P = 0.001). This indicated that MTrPs were stiffer than normal parts of the muscle.

CONCLUSION

This study presents a new method for the quantitative measurement of the elastic modulus of MTrP, thereby distinguishing MTrPs from normal adjacent muscular tissue, with more simplicity and lower cost, compared to other ultrasound methods.

Effect of fascia dry needling on non-specific thoracic pain - A proposed dry needling grading system

This case report describes a 42-year-old female who presented with complaints of diffuse pain in her thoracic paraspinal region from T2 to T7. Physical examination revealed tenderness, increased turgor and restriction of her superficial fascia. A potential first time description of successful management utilizing fascia dry needling is described in this report with improvements noted in pain, range of motion, and functional activities. The patient was discharged from physiotherapy after four treatment sessions, and a follow-up after 3 months revealed that she was pain free and fully functional. A grading system (Sudarshan and Murugavel Dry Needling Grading Scale^©) is proposed describing the various grades of dry needling to guide clinical reasoning and decision-making.

Experienced versus Inexperienced Interexaminer Reliability on Location and Classification of Myofascial Trigger Point Palpation to Diagnose Lateral Epicondylalgia: An Observational Cross-Sectional Study

The purpose was to evaluate the interexaminer reliability of experienced and inexperienced examiners on location and classification of myofascial trigger points (MTrPs) in two epicondylar muscles and the association between the MTrP found and the diagnosis of lateral epicondylalgia (LE). Fifty-two pianists (some suffered LE) voluntarily participated in the study. Three physiotherapists (one inexperienced in myofascial pain) examined, located, and marked MTrPs in the extensor carpi radialis brevis (ECRB) and extensor digitorum communis (EDC) muscles. Forearms were photographed and analyzed to establish the degree of agreement on MTrPs diagnosis. Data showed 81.73% and 77.88% of agreement on MTrP classification and 85.58% and 72.12% on MTrP location between the expert evaluators for ECRB and EDC, respectively. The agreement on MTrP classification between experienced and inexperienced examiners was 54.81% and 51.92% for ECRB and 50.00% and 55.77% for EDC. Also, agreement on MTrP location was 54.81% and 60.58% for ECRB and 48.08% and 48.08% for EDC. A strong association was found between presence of relevant MTrPs, LE diagnosis, and forearm pain when the examiners were experts. The analysis of location and classification of MTrPs in the epicondylar muscles through physical examination by experienced evaluators is reliable, reproducible, and suitable for diagnosing LE.

Quantification of Myofascial Taut Bands

OBJECTIVE

To assess the correlation of clinician-identified myofascial taut bands with their presence and characteristics on magnetic resonance elastography (MRE) imaging.

DESIGN

Cross-sectional study.

SETTING

A magnetic resonance imaging (MRI) research laboratory.

PARTICIPANTS

A convenience sample of adults (N=65; 45 women, 20 men) identified by skilled musculoskeletal physicians as having upper trapezius myofascial pain-associated taut bands.

INTERVENTIONS

Subjects had their taut bands outlined and were positioned within a 1.5T MRI machine. Shear waves were induced with a pneumatic transducer located over the belly of the involved muscle. Wave propagation was visualized with MRE images across a vibration cycle. Imaging data were assessed independently by 2 skilled MRE interpreters.

MAIN OUTCOME MEASURES

The primary outcome measure was the determination of the intra- and interrater reliabilities of MRE taut band identification and their correlation with clinician identification of band presence. Secondary outcomes consisted of the elucidation of the physical characteristics of taut bands and their surrounding muscle tissue.

RESULTS

MRE intra- and interrater reliability was excellent, with kappa coefficients and 95% confidence intervals (CIs) of .86 (.68-1.00) and .93 (.79-1.00), respectively. Stiffness in MRE-identified taut bands was elevated at a mean ± SD of 11.5±2.4 kPa and fell to 5.8±0.9 kPa in surrounding muscle tissue (P<.001); muscular tone in trapezius muscles without a taut band was relatively uniform at 6.6±2.1 kPa. Agreement between the physicians and the MRE raters, however, was relatively poor (63.1%; 95% CI, 50.2%-74.7%).

CONCLUSIONS

Our findings suggest that while clinicians may overestimate, and current MRE techniques may underestimate, the presence of taut bands, these bands do exist, can be assessed quantitatively, and do represent localized areas of increased muscle stiffness.

Quantifying the Elastic Property of Nine Thigh Muscles Using Magnetic Resonance Elastography

BACKGROUND

Pathologies of the muscles can manifest different physiological and functional changes. To adapt treatment, it is necessary to characterize the elastic property (shear modulus) of single muscles. Previous studies have used magnetic resonance elastography (MRE), a technique based on MRI technology, to analyze the mechanical behavior of healthy and pathological muscles. The purpose of this study was to develop protocols using MRE to determine the shear modulus of nine thigh muscles at rest.

METHODS

Twenty-nine healthy volunteers (mean age = 26 ± 3.41 years) with no muscle abnormalities underwent MRE tests (1.5 T MRI). Five MRE protocols were developed to quantify the shear moduli of the nine following thigh muscles at rest: rectus femoris (RF), vastus medialis (VM), vastus intermedius (VI), vastus lateralis (VL), sartorius (Sr), gracilis (Gr), semimembranosus (SM), semitendinosus (ST), and biceps (BC). In addition, the shear modulus of the subcutaneous adipose tissue was analyzed.

RESULTS

The gracilis, sartorius, and semitendinosus muscles revealed a significantly higher shear modulus (μ_Gr = 6.15 ± 0.45 kPa, μ_ Sr = 5.15 ± 0.19 kPa, and μ_ ST = 5.32 ± 0.10 kPa, respectively) compared to other tissues (from μ_ RF = 3.91 ± 0.16 kPa to μ_VI = 4.23 ± 0.25 kPa). Subcutaneous adipose tissue had the lowest value (μ_adipose tissue = 3.04 ± 0.12 kPa) of all the tissues tested.

CONCLUSION

The different elasticities measured between the tissues may be due to variations in the muscles' physiological and architectural compositions. Thus, the present protocol could be applied to injured muscles to identify their behavior of elastic property. Previous studies on muscle pathology found that quantification of the shear modulus could be used as a clinical protocol to identify pathological muscles and to follow-up effects of treatments and therapies. These data could also be used for modelling purposes.

A critical evaluation of the trigger point phenomenon

The theory of myofascial pain syndrome (MPS) caused by trigger points (TrPs) seeks to explain the phenomena of muscle pain and tenderness in the absence of evidence for local nociception. Although it lacks external validity, many practitioners have uncritically accepted the diagnosis of MPS and its system of treatment. Furthermore, rheumatologists have implicated TrPs in the pathogenesis of chronic widespread pain (FM syndrome). We have critically examined the evidence for the existence of myofascial TrPs as putative pathological entities and for the vicious cycles that are said to maintain them. We find that both are inventions that have no scientific basis, whether from experimental approaches that interrogate the suspect tissue or empirical approaches that assess the outcome of treatments predicated on presumed pathology. Therefore, the theory of MPS caused by TrPs has been refuted. This is not to deny the existence of the clinical phenomena themselves, for which scientifically sound and logically plausible explanations based on known neurophysiological phenomena can be advanced.

Dry needling: a literature review with implications for clinical practice guidelines

BACKGROUND

Wet needling uses hollow-bore needles to deliver corticosteroids, anesthetics, sclerosants, botulinum toxins, or other agents. In contrast, dry needling requires the insertion of thin monofilament needles, as used in the practice of acupuncture, without the use of injectate into muscles, ligaments, tendons, subcutaneous fascia, and scar tissue. Dry needles may also be inserted in the vicinity of peripheral nerves and/or neurovascular bundles in order to manage a variety of neuromusculoskeletal pain syndromes. Nevertheless, some position statements by several US State Boards of Physical Therapy have narrowly defined dry needling as an 'intramuscular' procedure involving the isolated treatment of 'myofascial trigger points' (MTrPs).

OBJECTIVES

To operationalize an appropriate definition for dry needling based on the existing literature and to further investigate the optimal frequency, duration, and intensity of dry needling for both spinal and extremity neuromusculoskeletal conditions.

MAJOR FINDINGS

According to recent findings in the literature, the needle tip touches, taps, or pricks tiny nerve endings or neural tissue (i.e. 'sensitive loci' or 'nociceptors') when it is inserted into a MTrP. To date, there is a paucity of high-quality evidence to underpin the use of direct dry needling into MTrPs for the purpose of short and long-term pain and disability reduction in patients with musculoskeletal pain syndromes. Furthermore, there is a lack of robust evidence validating the clinical diagnostic criteria for trigger point identification or diagnosis. High-quality studies have also demonstrated that manual examination for the identification and localization of a trigger point is neither valid nor reliable between-examiners.

CONCLUSIONS

Several studies have demonstrated immediate or short-term improvements in pain and/or disability by targeting trigger points (TrPs) using in-and-out techniques such as 'pistoning' or 'sparrow pecking'; however, to date, no high-quality, long-term trials supporting in-and-out needling techniques at exclusively muscular TrPs exist, and the practice should therefore be questioned. The insertion of dry needles into asymptomatic body areas proximal and/or distal to the primary source of pain is supported by the myofascial pain syndrome literature. Physical therapists should not ignore the findings of the Western or biomedical 'acupuncture' literature that have used the very same 'dry needles' to treat patients with a variety of neuromusculoskeletal conditions in numerous, large scale randomized controlled trials. Although the optimal frequency, duration, and intensity of dry needling has yet to be determined for many neuromusculoskeletal conditions, the vast majority of dry needling randomized controlled trials have manually stimulated the needles and left them in situ for between 10 and 30 minute durations. Position statements and clinical practice guidelines for dry needling should be based on the best available literature, not a single paradigm or school of thought; therefore, physical therapy associations and state boards of physical therapy should consider broadening the definition of dry needling to encompass the stimulation of neural, muscular, and connective tissues, not just 'TrPs'.