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Myofascial origin of shoulder pain: A literature review
Accepted Manuscript Myofascial origin of shoulder pain: a literature review Stanislav Sergienko , BPT Leonid Kalichman , PT, PhD PII:
S1360-8592(14)00076-X
DOI:
10.1016/j.jbmt.2014.05.004
Reference:
YJBMT 1132
To appear in:
Journal of Bodywork & Movement Therapies
Received Date: 4 February 2014 Revised Date:
4 April 2014
Accepted Date: 28 April 2014
Please cite this article as: Sergienko, S., Kalichman, L., Myofascial origin of shoulder pain: a literature review, Journal of Bodywork & Movement Therapies (2014), doi: 10.1016/j.jbmt.2014.05.004. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
ACCEPTED MANUSCRIPT Myofascial origin of shoulder pain: a literature review
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Stanislav Sergienko BPT, Leonid Kalichman PT, PhD*
Department of Physical Therapy, Recanati School for Community Health Professions,
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Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel
*Corresponding author. Leonid Kalichman, Department of Physical Therapy, Recanati
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School for Community Health Professions, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel. Tel: 972-52-2787050;
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Fax: 972-8-6477683. E-mail address: [email protected]
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ACCEPTED MANUSCRIPT ABSTRACT Background: Shoulder pain is a common problem imposing a considerable burden on the affected person and society. Since interventions targeting traditional musculoskeletal
an alternative possible source of shoulder pain.
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conditions are usually only moderately effective, myofascial origin can be suggested as
Objectives: To examine current evidence associated with myofascial origin of shoulder
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pain, with emphasis on diagnosis, prevalence and treatment efficacy.
Methods: PubMed, Google Scholar and PEDro databases were searched from inception
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until December 2013 for terms relating to myofascial pain in the shoulder area. Results: Two studies showed a high reliability of the following diagnostic characteristics during palpation: presence or absence of the taut band, spot tenderness, jump sign, pain recognition and referred pain sensation. Three prevalence studies
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showed a significant greater number of active myofascial trigger points (MTrPs) on the painful shoulder side. Reduced muscle strength, accelerated muscle fatigue, inconsistent muscle activation pattern under load and reduced antagonist reciprocal inhibition were
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found in subjects with latent MTrPs in four observational studies. Six interventional studies demonstrated the effectiveness of dry needling, myofascial manipulation,
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ischemic compression, laser therapy and multimodal treatment. Conclusion: MTrPs in shoulder muscles is a common condition among patients with shoulder complaints and can be reliably diagnosed by palpation. The reviewed interventions seem to be effective in reducing pain, increasing range of motion and improving function of the painful shoulder. KEYWORDS Myofascial pain; Myofascial trigger points; Shoulder pain; Treatment; Review
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ACCEPTED MANUSCRIPT INTRODUCTION Shoulder pain is a common musculoskeletal problem. It is the third most common cause of musculoskeletal consultation in primary care. Approximately 1% of adults annually
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consult a general practitioner with complaints of new shoulder pain (Urwin and others 1998). There are substantial disparities in reported 1-year prevalence of shoulder pain in the general population (4.7-46.7%), strongly influenced by various factors such as
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definition of shoulder disorders, including or excluding limited motion, age, gender and anatomic area (Luime and others 2004; Pope and others 1997). There is no clinical gold
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standard for defining shoulder pain. Shoulder complaints are usually identified as signs and symptoms in the deltoid, upper arm and scapular region, shoulder stiffness and reduced range of motion, often leading to limitations in daily activities (Pope and others 1997). Shoulder pain is widespread and imposes a considerable burden on the affected
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person and society. Swedish insurance data revealed that 18% of disability payments for musculoskeletal disorders was spent on neck and shoulder problems (van der Windt and others 2000). One of the most common causes of shoulder pain is subacromial
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impingement syndrome, comprising rotator cuff tendinopathy or subacromial bursitis. Infections, tumors and neural tissue pathologies are another possibility, but less
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common causes of shoulder pain (Bigliani and Levine 1997; Hawkins and Hobeika 1983; Koester and others 2005; Loitz and others 1999; Mayerhofer and Breitenseher 2004).
Since interventions targeting local subacromial conditions usually provide only
moderately effective treatment of shoulder complaints (Buchbinder and others 2003; Cummins and others 2009; Desmeules and others 2003; Dorrestijn and others 2009; Ekeberg and others 2009; Green and others 2003), alternative possible sources of
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ACCEPTED MANUSCRIPT shoulder pain should be considered. Studies have found a high prevalence of muscles containing active and latent Myofascial Trigger Points (MTrPs) with high local mechanical pain sensitivity and referred pain in patients with chronic non-traumatic
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shoulder pain (Alburquerque-Sendin and others 2013; Bron and others 2011b; Fernandez-de-las-Penas and others 2012; Ge and others 2006; Ge and others 2008).
MTrPs are described as local points, highly sensitive to pressure causing characteristic
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referred sensations, pain, muscle dysfunction and in some cases even sympathetic hyperalgesia (Ge and others 2006; Simons and others 1999).
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MTrPs may be classified as active or latent. Active MTrPs are characterized by the presence of clinical pain and constant tenderness, preventing full lengthening and leading to weakening of the muscle. Diagnostically, active MTrPs refer to patientrecognized pain upon compression and mediate a local twitch response in muscle fibers
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when adequately stimulated. When compressed, active MTrPs produce referred motor phenomena and often autonomic phenomena, generally in its pain reference zone. In contrast, latent MTrPs are clinically quiescent with respect to spontaneous pain, and are
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painful only when palpated. A latent MTrP may have all the clinical characteristics of active MTrP, always with a taut band that increases muscle tension and restricts range
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of motion (Simons and others 1999). Another contribution of MTrPs to shoulder pain may be related to the weakening
and accelerated fatigability of affected muscles thus altering their activation patterns during shoulder movements (Celik and Yeldan 2011; Ge and others 2012; Ibarra and others 2011; Lucas and others 2010). Subacromial impingement syndrome can be associated with abnormal extrinsic mechanics including faulty posture, altered scapular or glenohumeral kinematics, increased anterior and superior humeral head translations,
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ACCEPTED MANUSCRIPT decreased scapular posterior tipping, external rotation and upward rotation. Hence, weakness or fatigue of the muscles controlling these articulations may play a critical role in the development of subacromial impingement syndrome and shoulder pain
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(Michener and others 2003). Despite the possible importance of a myofascial component, reviews addressing the efficacy of interventions for disorders resulting in shoulder pain, stiffness and
Green and others 2003; Green and others 2005).
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disability rarely mention myofascial pain or MTrP therapy (Green and others 2000;
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The purpose of this review was to examine the current evidence associated with myofascial origin of shoulder pain, with emphasis on diagnosis, prevalence and treatment efficacy.
METHODS
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PubMed, Google Scholar and PEDro databases were searched from inception until December 2013, using a predefined search strategy. Databases were searched for the key words "shoulder", "pain", "myofascial", "trigger point" and various combinations.
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Titles and abstracts of all articles mentioning at least one of the key words were reviewed. Studies of any design or methodological quality, except case reports, dealing
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with MTrPs prevalence in the shoulder area, their effect on shoulder muscle function, clinical diagnosis and any kind of treatment were included. Articles were excluded if they were associated with myofascial pain after surgery, myofascial pain in cancer or fibromyalgia patients, myofascial trigger points not related to shoulder pain, injections or other pharmacological interventions for myofascial pain. Study protocol articles and articles without available full text were also excluded from the review. There were no
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ACCEPTED MANUSCRIPT search limitations or language restrictions. The reference lists of all articles retrieved in full were also searched. The methodological quality of interventional studies was evaluated using the
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PEDro score checklist (http://www.pedro.org.au/). The PEDro scale considers two aspects of trial quality, the "internal validity" of the trial and whether the trial contains
validity" of the trial, or the size of the treatment effect. RESULTS
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sufficient statistical information to make it interpretable. It does not rate the "external
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The search strategy initially revealed 88 papers. Of them, 16 studies met the inclusion criteria and were included in this review.
Evaluation of MTrPs in shoulder muscles
Only two relevant studies dealing with the evaluation of MTrPs in shoulder muscles
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were found. One study investigated the test-retest reliability (three day interval, by the same expert) of MTrP diagnostic characteristics, such as taut band, spot tenderness, jump sign, pain recognition, referred pain and local twitch responses (Al-Shenqiti and
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Oldham 2005). Fifty-eight patients (31 males and 27 females, mean age 48.4 years) with rotator cuff tendonitis participated in the study. Kappa values between testing
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situations for the taut band, spot tenderness, jump sign and pain recognition were 1. Kappa values for referred pain ranged between 0.79 and 0.88 and for the local twitch response between 0.75 and 1, depending on the muscles under investigation. Kappa value for twitch response of supraspinatus and subscapularis could not be calculated as this sign was absent in all patients (Al-Shenqiti and Oldham 2005). In the second observational study, three experienced physical therapists bilaterally palpated the infraspinatus, anterior deltoid, and biceps brachii muscles for a total of 12
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ACCEPTED MANUSCRIPT MTrPs (Bron and others 2007). The raters were blinded as to whether the shoulder of the subject was painful. Forty subjects (16 male and 24 female, 40 ± 11.5 years old) participated in the study, eight were asymptomatic and 32 had unilateral or bilateral
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shoulder pain. The most reliable features of MTrPs were the referred pain sensation and jump sign. The percentage of pair-wise agreement (PA) was ≥ 70% (range 63-93%) for referred pain sensation. For the jump sign, PA was ≥ 70% (range 67-77%). Finding a
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nodule in a taut band (PA = 45-90%) and eliciting a local twitch response (PA = 33-
100%) were shown to be least reliable. The highest inter-tester agreement regarding the
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presence or absence of MTrPs was found in the palpation of infraspinatus muscle (PA = 69-80%) (Bron and others 2007). The summary of studies on evaluation of MTrPs in shoulder muscles is presented in Table 1.
Prevalence of MTrPs in shoulder muscles and association with symptoms
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The number of MTrPs bilaterally in the infraspinatus muscles was assessed in an observational study of 21 females, 46.3 ± 4.2 years old, with chronic unilateral myofascial shoulder pain (Ge and others 2008). The number of MTrPs was significantly
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greater (p< 0.001) on the painful side (2.45 ± 0.13) than the non-painful side (1.37 ± 0.12). The number of active (2.31 ± 0.13) and latent (2.58 ± 0.13) MTrPs was similar on
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the painful side (P > 0.05), while on the non-painful side, there were only latent MTrPs (2.73 ± 0.13).
Another study evaluated the presence of MTrPs in the shoulder muscles of 72
subjects (22 males and 50 females, 43.9 ± 12.3 years old) with unilateral nontraumatic shoulder pain; the non-affected shoulder was examined as a control (Bron and others 2011b). The median number of muscles with MTrPs per subject was 6 for active and 4 for latent. Active MTrPs were most prevalent in the infraspinatus (77%) and the upper
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ACCEPTED MANUSCRIPT trapezius muscles (58%); latent MTrPs were most prevalent in the teres major (49%) and anterior deltoid muscles (38%). An additional study compared the number of MTrPs bilaterally in 10 shoulder
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muscles in two groups (Alburquerque-Sendin and others 2013). The shoulder impingement syndrome group consisted of 27 patients (13 males and 14 females, 35.6 ± 12.1 years old) with unilateral shoulder pain. The control group consisted of 20 healthy
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right-handed patients (9 males and 11 females, 37.0 ± 11.2 years old). Taking into
account both sides, the impingement group showed a greater number of MTrPs than the
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controls (p=0.01). The total number of muscles with MTrPs was higher on the involved side (4.7 ± 3.1) than on the dominant side in the control group (2.2 ± 2.8) (p=0.017), however no differences were detected with respect to the uninvolved side (3.2 ± 3.0). For latent MTrPs, no differences were found between sides (p>0.05), while the involved
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side presented a higher number (p=0.003) of active MTrPs (3.3 ± 3.0) compared with the uninvolved side (1.1 ± 2.2) (Alburquerque-Sendin and others 2013). Consecutive blue-collar or white-collar workers with chronic pain in the upper
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quadrant were investigated in another study (Fernandez-de-las-Penas and others 2012). In the blue-collar workers group that included 6 males and 10 females, 44 ± 13 years
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old, a mean of 6 ± 3 active and 10 ± 5 latent MTrPs were present. In the white-collar workers group that included 6 male and 13 females, 44 ± 14 years old, it was a mean of 6±4 active and 11±6 latent MTrPs. Active MTrPs in the upper trapezius, infraspinatus, levator scapulae, and extensor carpi radialis brevis muscles were most prevalent in both groups. No significant differences were found for the total number, the number of active or the number of latent MTrPs between groups (all p>0.05). Significant differences in referred pain areas between muscles were found (p<0.001) with the pectoralis major,
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ACCEPTED MANUSCRIPT infraspinatus, upper trapezius, and scalene muscle MTrPs showing the largest referred pain areas (p<0.01) (Fernandez-de-las-Penas and others 2012). The summary of studies on MTrPs prevalence in shoulder muscles is presented in Table 2.
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Effect of MTrPs on shoulder muscles function The study was designed to assess flexion and scaption strength in both shoulders using a hand-held dynamometer (Celik and Yeldan 2011). Group 1 included 28 healthy subjects
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(12 male and 16 female, 24.25 ± 4.9 years old) with at least two latent MTrPs located on the dominant side of the scapular muscles (upper and middle trapezius, supraspinatus,
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serratus anterior and rhomboids major and minor). Group 2 included 23 healthy subjects (18 males and 5 females, 23.52 ± 4.2 years old) without any MTrPs. No significant differences were found in muscle strength between dominant and non-dominant sides in both groups (p>0.05); both sides muscle strength in Group 1 was significantly lower
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than in Group 2 (p<0.05).
Another study recruited 12 healthy volunteers (8 males and 4 females, 27.4 ± 3.6 years old) with no signs or symptoms of musculoskeletal pain (Ge and others 2012).
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Each subject had at least one latent MTrP bilaterally in the upper trapezius muscle. Surface electromyographic (EMG) recordings and intramuscular EMG from latent
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MTrPs and non-MTrPs were obtained from the upper trapezius muscles during sustained isometric contractions. Intramuscular EMG from latent MTrPs showed an early decrease in mean power frequency and a significant decrease at the end of a fatiguing contraction compared with non-MTrPs (p<0.05). Surface EMG from muscle fibers close to latent MTrPs presented with an early increase in normalized root mean square amplitude. The increase was significantly higher than that of non-MTrPs at the end of a sustained isometric contraction (p<0.05). According to these findings, latent
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ACCEPTED MANUSCRIPT MTrPs are associated with an accelerated development of muscle fatigue, simultaneously overloading other active motor units (Ge and others 2012). An observational study employed surface EMGs to measure the timing of muscle
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activation onset of the upper and lower trapezius, serratus anterior, infraspinatus and middle deltoid muscles initially without load and with a light dumbbell in two groups (Lucas and others 2010). The MTrPs group included 28 subjects (16 males and 12
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females, 33.9 ± 11.4 years old) with at least one latent MTrP in the scapular positioning muscles on the dominant side, but not in the infraspinatus or middle deltoid. The control
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group included 14 subjects (7 males and 7 females, 35.6 ± 8.6 years old) with no latent MTrPs in any of the test muscles. The control group displayed a relatively stable sequence of muscle activation significantly different in timing and variability to that of the latent MTrPs group in all muscles except the middle deltoid (all p<0.05). The latent
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MTrPs group muscle activation pattern under load was inconsistent, the only common feature being early activation of the infraspinatus (Lucas and others 2010). Intramuscular and surface EMG activity between antagonist muscles was
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investigated in another study (Ibarra and others 2011). Fourteen healthy asymptomatic subjects (12 males and 2 females, 26 ± 6.9 years old) participated in a 2-trial study in
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which latent and non-MTrP were detected by palpation in the posterior deltoid muscle. This experiment consisted of 2 sessions with an intramuscular EMG needle electrode inserted into either a latent MTrP or a non-MTrP in the posterior deltoid muscle on the dominant side. The intramuscular EMG activity, but not surface EMG activity in the antagonist muscle, was significantly higher at rest and during shoulder flexion with latent MTrPs than non-MTrPs (p<0.05), signifying reduced antagonist reciprocal
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ACCEPTED MANUSCRIPT inhibition (Ibarra and others 2011). The summary of studies on the effect of MTrPs on shoulder muscles function is presented in Table 3. Treatment of MTrPs in shoulder muscles
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The search strategy revealed six studies dealing with myofascial pain treatment in the shoulder area. Characteristics and results of the reviewed intervention studies are shown in Tables 4 and 5, respectively.
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In a single-blinded within-subject design study, 14 patients with bilateral shoulder pain and active MTrPs in the infraspinatus muscles were evaluated (Hsieh and others
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2007). An MTrP in the infraspinatus muscle on a randomly selected side was dry needled; the contralateral side MTrPs was untreated and used as a control. Shoulder pain intensity was assessed by the Visual Analogue Scale (VAS). Internal rotation active and passive range of motion and pressure pain threshold (PPT) of the MTrPs was
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measured on both sides before and immediately after dry needling. All outcome measures significantly improved only on the treated side (p<0.01). Another study designed as a cross-over randomized control trial (RCT) evaluated
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the effect of 15 ischemic compression (IC) sessions on shoulder MTrPs in 59 patients with chronic shoulder pain (Hains and others 2010). A validated 13-question Shoulder
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Pain and Disability Index (SPADI) questionnaire was used to measure shoulder pain and functional impairment. After the first 15 treatments, the experimental group demonstrated a significant reduction in the SPADI score compared with the control group (p<0.05). The control group subjects also significantly reduced their SPADI scores after the cross-over (p<0.001). Another RCT assessed the effectiveness of multimodal treatment of MTrPs in patients with chronic shoulder pain (Bron and others 2011a). Thirty-four experimental
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ACCEPTED MANUSCRIPT group subjects received a 12 week treatment program. Manual compression of the MTrPs, manual stretching of the muscles and intermittent cold application with stretching was performed once a week by a physical therapist. Patients were instructed
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to perform muscle-stretching and relaxation exercises at home and received ergonomic recommendations and advice as to maintaining good posture. Thirty-one control group subjects remained on the waiting list for 3 months. Compared with the controls after 12
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weeks of treatment, the intervention group showed significant improvement according to the Disabilities of Arm, Shoulder and Hand (DASH) score and VAS (all p<0.05)
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(Bron and others 2011a).
The effectiveness of low-level laser therapy in treating shoulder MTrPs was evaluated in another RCT (Yamany and Salim 2011). Forty patients with unilateral shoulder pain and at least three MTrPs in the deltoid and/or upper trapezius muscles
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were randomly assigned into active and placebo laser groups. The subjects received 12 treatment sessions during a 4 week period, 3 sessions a week. A stretching and strengthening exercise program was performed daily under
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supervision in a clinic and at home for all patients in both groups. After 4 weeks of treatment, VAS and active range of motion significantly improved in both groups. PPT
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significantly increased only in the active laser group (all p < 0.0001). Compared with the placebo group, the active laser group made significant improvements in all outcomes (all p < 0.01) (Yamany and Salim 2011). A quasi-experimental study was designed to evaluate the effect of three fascial
manipulation sessions on chronic posterior brachial pain in 28 patients (Day and others 2009). Fascial manipulation involves applying local deep friction to specific areas over the deep fascia, identified as centers of coordination (Stecco 2004). The densification of
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ACCEPTED MANUSCRIPT fascia (lack of gliding between layers of fascia and between fascia and adjacent structures) was assumed to be associated with myofascial pain (Stecco and others 2013). VAS measurement of pain prior to the first session and after the third session was
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compared with a follow-up evaluation at three months. A mean pain reduction of 57% was obtained after the third session (p<0.0001) and remained without significant
changes (p>0.05) when reassessed after a three month follow-up (Day and others
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2009).
A cohort study assessed the short-term effect of IC for MTrPs on muscle strength,
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mobility, pain sensitivity, and disability in office workers and the effect on disability and general pain at 6-month follow-up (Cagnie and others 2013). Nineteen subjects completed the study and were included for the analyses. All the participants were righthanded office workers performing at least 4 hours of computer work and were
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answering the following criteria: (1) neck/shoulder pain or discomfort of > 30 days during the last year in the neck or shoulder region, (2) pain frequency of at least once a week, and (3) an intensity of pain of at least 2 on a scale from 0 to 10.
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Outcome measures were general neck and shoulder complaints on a Numeric Rating Scale (NRS), Neck Disability Index (NDI), passive neck flexion-extension and
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side flexion measured by inclinometer, neck and shoulder muscle strength measured by dynamometer, and PPT assessed by NRS and algometry. Subjects were tested at baseline (pre-control), after a control period of no treatment of 4 weeks (post-control), and after 4-week intervention training (post-treatment). At 6-month follow-up general neck/shoulder pain and disability were reassessed. All the subjects received 8 sessions of treatment (4 weeks, 2 times a week), consisting of IC on the 4 most painful MTrPs selected during the first testing session. IC
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ACCEPTED MANUSCRIPT consisted of pressure that was gradually increased until the subject experienced his/her highest tolerable pain and was sustained for one minute. The results showed a statistically significant decrease in general neck/shoulder
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pain at post-treatment (p =0.001) and at 6-month follow-up (p = 0.003) compared with pre-control and post-control. There was no significant main effect for NDI scores. PPP increased at post-treatment in all 4 treated MTrPs (p <0.001). There was a significant
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treatment (p<0.05) (Cagnie and others 2013).
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increase in range of motion and muscle strength from pre-control/post-control to post-
DISCUSSION
Two studies assessed the reliability of MTrPs clinical diagnosis in the shoulder region focusing on diagnostic characteristics during palpation. High reliability of presence or
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absence of the taut band, spot tenderness, jump sign, pain recognition and referred pain sensation demonstrated that MTrP palpation is a useful and reliable tool in diagnosing myofascial pain in patients with non-traumatic shoulder pain (Al-Shenqiti and Oldham
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2005; Bron and others 2007).
Prevalence studies have shown a significant greater number of active MTrPs on
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the painful shoulder side. In contrast, no significant difference was found in the number of latent MTrPs between painful and non-painful shoulder muscles. Active MTrPs were most prevalent in the infraspinatus, upper trapezius and levator scapulae muscles (Alburquerque-Sendin and others 2013; Bron and others 2011b; Ge and others 2008). Surprisingly, no significant difference was found in the total number of shoulder MTrPs between white-collar and blue-collar workers (Fernandez-de-las-Penas and others
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ACCEPTED MANUSCRIPT 2012). Obviously, type of work is not a key factor in upper quadrant MTrPs development. Other contributing factors should be investigated in future studies. The effect of MTrPs on shoulder muscle function was evaluated in four
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observational studies. Reduced muscle strength, accelerated muscle fatigue and simultaneous overloading active motor units were found in subjects with latent MTrPs (Celik and Yeldan 2011; Ge and others 2012). In addition, two EMG studies assessing
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the interaction between shoulder muscles and latent MTrP showed an inconsistent
muscle activation pattern under load and reduced antagonist reciprocal inhibition (Ibarra
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and others 2011; Lucas and others 2010). These findings may have an important clinical implication for diagnosis and treatment of disorders associated with abnormal shoulder muscle function, i.e. subacromial or subcoracoid impingement syndromes, rotator cuff or biceps tendinopathy, etc.
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The association between prevalence of active MTrPs and shoulder pain and the influence of MTrPs on shoulder muscle function emphasizes the importance of evaluating myofascial pain in every case of shoulder pain. We feel that myofascial pain
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evaluation should become routine when evaluating shoulder pain. Reviewed studies on the treatment of shoulder myofascial pain, demonstrated the
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effectiveness of dry needling, myofascial manipulation, IC, laser therapy and multimodal treatment that included manual MTrPs compression, manual muscles stretching, cold application, home exercises and ergonomic recommendations. Most studies used VAS of pain intensity as an outcome measure, usually combined with range of motion, functional scales or PPT (Bron and others 2011a; Day and others 2009; Hains and others 2010; Hsieh and others 2007; Yamany and Salim 2011). Since significant electromyographic changes were found in muscles affected by MTrPs (Ge
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ACCEPTED MANUSCRIPT and others 2012; Ibarra and others 2011; Lucas and others 2010), EMG recordings could be used as additional quantitative outcome measure in future MTrPs treatment studies.
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CONCLUSIONS Presence of MTrPs in shoulder muscles is a common condition among patients with
shoulder complaints. Therefore, the myofascial component should be considered as a
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possible primary or secondary source of shoulder pain during clinical examination.
The reviewed interventions for shoulder muscle MTrPs seem to be effective in
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reducing pain, increasing range of motion and improving function of the painful shoulder. Additional studies are needed to identify the contributing factors and causes of MTrPs development in the shoulder area in order to establish preventive strategies for
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these conditions.
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ACCEPTED MANUSCRIPT ACKNOWLEDGEMENTS
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The authors thank Mrs Phyllis Curchack Kornspan for her editorial services.
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Ge HY, Fernandez-de-Las-Penas C, Madeleine P, Arendt-Nielsen L. 2008. Topographical mapping and mechanical pain sensitivity of myofascial trigger points in the infraspinatus muscle. Eur J Pain 12(7):859-65.
Cochrane Database Syst Rev(2):CD001156.
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Green S, Buchbinder R, Glazier R, Forbes A. 2000. Interventions for shoulder pain.
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Green S, Buchbinder R, Hetrick S. 2003. Physiotherapy interventions for shoulder pain. Cochrane Database Syst Rev(2):CD004258.
Green S, Buchbinder R, Hetrick S. 2005. Acupuncture for shoulder pain. Cochrane Database Syst Rev(2):CD005319.
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Hains G, Descarreaux M, Hains F. 2010. Chronic shoulder pain of myofascial origin: a randomized clinical trial using ischemic compression therapy. J Manipulative Physiol Ther 33(5):362-9.
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Hawkins RJ, Hobeika PE. 1983. Impingement syndrome in the athletic shoulder. Clin Sports Med 2(2):391-405.
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Hsieh YL, Kao MJ, Kuan TS, Chen SM, Chen JT, Hong CZ. 2007. Dry needling to a key myofascial trigger point may reduce the irritability of satellite MTrPs. Am J Phys Med Rehabil 86(5):397-403.
Ibarra JM, Ge HY, Wang C, Martinez Vizcaino V, Graven-Nielsen T, Arendt-Nielsen L. 2011. Latent myofascial trigger points are associated with an increased antagonistic muscle activity during agonist muscle contraction. J Pain 12(12):1282-8.
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ACCEPTED MANUSCRIPT Koester MC, George MS, Kuhn JE. 2005 .Shoulder impingement syndrome. Am J Med 118(5):452-5. Loitz D, Loitz S, Reilmann H. 1999. [The subacromial-syndrome. Diagnosis,
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conservative and operative treatment]. Unfallchirurg 102(11):870-87. Lucas KR, Rich PA, Polus BI. 2010. Muscle activation patterns in the scapular
positioning muscles during loaded scapular plane elevation: the effects of Latent
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Myofascial Trigger Points. Clin Biomech (Bristol, Avon) 25(8):765-70.
Luime JJ, Koes BW, Hendriksen IJ, Burdorf A, Verhagen AP, Miedema HS, Verhaar
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JA .2004 .Prevalence and incidence of shoulder pain in the general population; a systematic review. Scand J Rheumatol 33(2):73-81.
Mayerhofer ME, Breitenseher MJ. 2004. [Impingement syndrome of the shoulder]. Radiologe 44(6):569-77.
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Michener LA, McClure PW ,Karduna AR. 2003. Anatomical and biomechanical mechanisms of subacromial impingement syndrome. Clin Biomech (Bristol, Avon) 18(5):369-79.
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Pope DP, Croft PR, Pritchard CM, Silman AJ. 1997. Prevalence of shoulder pain in the community: the influence of case definition. Ann Rheum Dis 56(5):308-12.
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Simons DG, Travell JG, Simons LS. 1999. Travell and Simons’ Myofascial Pain and Dysfunction: The Trigger Point Manual. Baltimore, MD: Williams & Wilkins.
Stecco A, Gesi M, Stecco C, Stern R. 2013. Fascial components of the myofascial pain syndrome. Curr Pain Headache Rep 17(8):352.
Stecco L. 2004. Fascial Manipulation. Padova: Piccin. Urwin M, Symmons D, Allison T, Brammah T, Busby H, Roxby M, Simmons A, Williams G. 1998. Estimating the burden of musculoskeletal disorders in the
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ACCEPTED MANUSCRIPT community: the comparative prevalence of symptoms at different anatomical sites, and the relation to social deprivation. Ann Rheum Dis 57(11):649-55. van der Windt DA, Thomas E, Pope DP, de Winter AF, Macfarlane GJ, Bouter LM,
review. Occup Environ Med 57(7):433-42.
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Silman AJ. 20 .00Occupational risk factors for shoulder pain: a systematic
Yamany AA, Salim SE. 2011. Efficacy of Low Level Laser Therapy for Treatment
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Myofascial Trigger Points of Shoulder Pain. World Applied Sciences Journal
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1.758-764:(6)2
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Table 1. Summary of studies on evaluation of MTrPs in shoulder muscles. Design
Participants
Shenqiti
test-retest
rotator cuff
reliability, three
tendonitis
Mean
(male/female)
age
58 (31/27)
48.4
& Oldham day interval, by the
8 asymptomatic and
reliability between
32 with unilateral or
three experienced
bilateral shoulder
physical therapists
pain
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2007
Inter-tester
40 (16/24)
40 ± 11.5
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Bron et al
same expert
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2005
Kappa value
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Al-
N
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Inclusion Criteria
Outcome
Results
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Study
Kappa values for the taut band, spot tenderness,
jump
sign
and
pain
recognition were 1. Kappa values for referred pain ranged between 0.79 and 0.88 and for the local twitch response between 0.75 and 1
Percentage of
The most reliable features of MTrPs
pair-wise
diagnosis were referred pain sensation
agreement
(PA ≥ 70%, range 63-93%) and jump
(PA)
sign (PA ≥ 70%, range 67-77%)
PA - Percentage of pair-wise agreement, MTrPs – myofascial trigger points.
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Table 2. Summary of MTrPs prevalence in shoulder muscles studies. Participants N
Mean
(male/female)
age
Chronic unilateral
21
46.3 ±
The number of
shoulder pain
(0/21)
4.2
MTrPs bilaterally in
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Ge et al 2008
Results
nontraumatic
(22/50)
shoulder pain
43.9 ± 12.3
0.001) on the painful side (2.45 ± 0.13) than the non-
the infraspinatus
painful side (1.37 ± 0.12). The number of active
muscles
(2.31 ± 0.13) and latent (2.58 ± 0.13) MTrPs was
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72
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unilateral
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Bron et al 2011
The number of MTrPs was significantly greater (p<
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Inclusion Criteria
Outcome
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Study
similar on the painful side (P > 0.05), while on the non-painful side only latent MTrPs were found (2.73 ± 0.13)
The presence of
The median number of muscles with MTrPs per
MTrPs in the
subject was 6 for active and 4 for latent. Active
shoulder muscles
MTrPs were most prevalent in the infraspinatus (77%) and the upper trapezius muscles (58%); latent MTrPs were most prevalent in the teres major (49%) and anterior deltoid muscles (38%)
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shoulder
27
35.6 ±
The number of
The impingement group showed a greater number of
Sendin et al
impingement
(13/14)
12.1
MTrPs bilaterally in
MTrPs than the controls (p=0.01). The total number
2013
syndrome with
shoulder muscles in
of muscles with MTrPs was higher on the involved
unilateral shoulder
two groups
control group (2.2 ± 2.8) (p=0.017), no differences
37.0 ±
handed patients
(9/11)
11.2
16
las-Penas et al
workers with
(6/10)
2012
chronic pain in the
44 ±
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blue-collar
13
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Fernandez-de-
white-collar workers with
19
were detected with respect to the uninvolved side
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20
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healthy right-
upper quadrant
side (4.7 ± 3.1) than on the dominant side in the
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pain
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Alburquerque-
44 ±
(3.2 ± 3.0). For latent MTrPs, no differences were found between sides (p>0.05), while the involved side presented a higher number (p=0.003) of active MTrPs (3.3 ± 3.0) compared with the uninvolved side (1.1 ± 2.2)
The number of
A mean of 6 ± 3 active and 10 ± 5 latent MTrPs were
active and latent
present in the blue-collar workers group, compared to
MTrPs in both
6±4 active and 11±6 latent MTrPs in the white-collar
groups.
group. No significant differences were found for the
The referred pain
total number, the number of active or the number of
areas (drawn on
latent MTrPs between groups (all p>0.05).
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(6/13)
14
upper quadrant
anatomic maps,
Significant differences in referred pain areas between
digitized, and
muscles were found (p<0.001) with the pectoralis
measured)
major, infraspinatus, upper trapezius, and scalene
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chronic pain in the
muscle MTrPs showing the largest referred pain
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areas (p<0.01).
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MTrPs – myofascial trigger points.
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Table 3. Summary of studies on the effect of MTrPs on shoulder muscles function. Participants Inclusion Criteria
Outcome N
Mean
(male/female)
age
Results
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Study
Healthy subjects with ≥
28
24.25
flexion and scaption strength in
Yeldan
latent MTrPs located on
(12/16)
± 4.9
both shoulders using a hand-
2011
the dominant side of the
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Celik &
held dynamometer
scapular muscles 23
23.52
without any MTrPs
(18/5)
± 4.2
Ge et al
Healthy volunteers with
12
2012
≥one latent MTrP
(8/4)
trapezius muscle
muscle strength between dominant and nondominant sides in both groups (p>0.05). Both sides muscle strength in group with MTrPs was significantly lower than in group without MTrPs (p<0.05).
27.4 ± Surface and intramuscular EMG Intramuscular EMG from latent MTrPs from latent MTrPs and non-
showed an early decrease in mean power
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3.6
MTrPs from the upper trapezius frequency and a significant decrease at the
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bilaterally in the upper
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Healthy subjects
No significant differences were found in
muscles during sustained isometric contractions
end of a fatiguing contraction compared with non-MTrPs (p<0.05). Surface EMG from muscle fibers close to latent MTrPs presented with an early
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increase in normalized root mean square amplitude. The increase was significantly
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higher than that of non-MTrPs at the end of a sustained isometric contraction (p<0.05)
≥ One latent MTrP in
28
33.9 ±
Timing of muscle activation
al 2010
the scapular positioning
(16/12)
11.4
onset of the upper and lower
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Lucas et
muscles on the
trapezius, serratus anterior,
dominant side 14 (7/7)
MTrPs
35.6 ±
muscles with and without light
8.6
load
Healthy asymptomatic
14
26 ±
and
subjects
(12/2)
6.9
significantly
of
muscle
different
in
activation
timing
and
in all muscles except the middle deltoid (all p<0.05)
activity of latent MTrP or a
surface EMG activity in the antagonist
non-MTrP in posterior deltoid
muscle, was significantly higher at rest and
muscle (antagonist) during
during shoulder flexion with latent MTrPs
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2011)
sequence
Intramuscular and surface EMG The intramuscular EMG activity, but not
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(Ibarra
others
stable
infraspinatus and middle deltoid variability to that of the latent MTrPs group
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Controls with no latent
The control group displayed a relatively
shoulder flexion
than non-MTrPs (p<0.05)
MTrPs – myofascial trigger points, EMG – electromyography.
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Table 4. Characteristics of the reviewed shoulder myofascial pain treatment studies. Experimental Group Mean
Inclusion
(male/female)
Age
Criteria
14 (8/6)
Intervention
60.2±13.2 Bilateral
1 session of
The same 14
subjects from the
shoulder pain +
MTrP dry
2007
Infraspinatus
needling
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et al
MTrPs
3 sessions of
et al
posterior
fascial
2009
brachial pain 41 (21/20)
26.7
46.5±8.8
Shoulder pain
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Chronic
Hains
28 (13/15)
for at least the
2010
past 3 months
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et al
Age
Inclusion
Intervention
Criteria
60.2±13.2 Bilateral shoulder pain +
treatment group
Infraspinatus
used as a control
MTrPs
-
-
18 (5/13)
45.6±7.4
-
-
-
manipulation
15 sessions of
Shoulder pain
15 sessions of
ischemic
for at least the
ischemic
compression on
past 3 months
compression on
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Day
N (male/female)
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Hsieh
N
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Study
Control Group
shoulder muscle
cervical muscle
MTrPs (once a
MTrPs (once a
week)
week)
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Table 4. Characteristics of the reviewed shoulder myofascial pain treatment studies (cont).
al
(13/21)
42.8±11.7
2011
Unilateral
12 week program of
31
nontraumatic
manual MTrPs
shoulder pain for
compression and muscles
at least 6 months
stretching, cold
45.0±13.2 Unilateral
(8/23)
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34
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Bron et
application, stretching and
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relaxation exercises at
Remained on
nontraumatic
the waiting list
shoulder pain
for 3 months
for at least 6 months
home, ergonomic
recommendations
(12/8)
2011
32.6±2.79
Unilateral
12 sessions of laser during
shoulder pain with at least three
20
34.8±7.22 Unilateral
12 sessions of
a 4 week period, combined (10/10)
shoulder pain
placebo laser
with an exercise program
with at least
during a 4
three MTrPs
week period,
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MTrPs
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et al
20
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Yamany
combined with an exercise program
Cagnie
19
39.47±8.32 Office workers
8 sessions of IC during a 4
-
-
-
-
30
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2013
(3/16)
with mild neck
week period, applied on 4
and shoulder
most painful MTrPs
complaints for
identified during
more than 30 days examination
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during the last
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et al
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MTrPs – myofascial trigger points; IC – ischemic compression
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year
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Table 5. Results of the reviewed should myofascial pain treatment studies.
5/10
al 2007
Outcome
Short Term
Long Term (Follow-up)
Shoulder IR AROM
Increase in treatment side (p <0.01)
-
Shoulder IR PROM
Increase in treatment side (p <0.01)
-
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Hsieh et
PEDro
Infraspinatus MTrPs PPT Increase in treatment side (p <0.01)
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Study
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Findings
-
Reduction in treatment side (p<0.001)
Pain intensity by VAS
Mean pain reduction of 57% after 3rd
The benefit did not significantly change at the
2009
session (p<0.0001)
three month follow-up (p>0.05)
Hains et
Reduction in experimental group SPADI
Reduction in experimental group SPADI scores
scores compared with controls (p<0.05)
after 6 months (p<0.001). Reduction in control
9/10
SPADI score
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al 2010
3/10
-
group SPADI scores after crossover (p<0.001)
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Day et al
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Pain intensity by VAS
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Table 5. Results of the reviewed should myofascial pain treatment studies (cont). DASH score
group compared with controls (p<0.05)
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2011
6/10 VAS score for current pain,
Reduction in experimental group VAS scores
average and most severe
compared with the controls (all p<0.05)
et al 2011
VAS
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pain during the past 7 days Yamany
-
-
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Bron et al
Functional improvement in experimental
VAS and AROM significantly improved in
8/10 Shoulder Flex/Abd AROM
both groups, PPT significantly increased only in the active laser group (all p < 0.0001)
PPT
-
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Compared with placebo, the active laser group showed significant improvements in all
General neck/shoulder
et al
complaints by NRS
NRS significantly decreased at post treatment
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Cagnie
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outcomes (all p < 0.01) At 6-month follow-up NRS was still
(p = 0.001) compared with
significantly lower compared with
precontrol/postcontrol
precontrol/postcontrol (p = 0.003)
NDI
No significant difference (p = 0.079)
No significant difference (p = 0.079)
Cervical PROM
Significant increase in flexion-extension
2013
-
33
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(p = 0.003) and side flexion (p ≤ .001) compared with precontrol/postcontrol Significant increase in PPT compared with precontrol/postcontrol (p<0.001)
All strength scores significantly increased
-
-
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Muscle Strength
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PPT
(p<0.05)
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compared with precontrol /postcontrol
IR AROM - Internal Rotation Active Range of Motion; IR PROM - Internal Rotation Passive Range of Motion; PPT - Pressure Pain Threshold; VAS - Visual Analog Sale; SPADI - The Shoulder Pain and Disability Index; DASH - The Disabilities of Arm, Shoulder and
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NDI - Neck Disability Index.
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Hand; Flex/Abd AROM - Flexion/Abduction Active Range of Motion; MTrPs – myofascial trigger points; NRS - Numeric Rating Scale;
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S1360-8592(14)00076-X
DOI:
10.1016/j.jbmt.2014.05.004
Reference:
YJBMT 1132
To appear in:
Journal of Bodywork & Movement Therapies
Received Date: 4 February 2014 Revised Date:
4 April 2014
Accepted Date: 28 April 2014
Please cite this article as: Sergienko, S., Kalichman, L., Myofascial origin of shoulder pain: a literature review, Journal of Bodywork & Movement Therapies (2014), doi: 10.1016/j.jbmt.2014.05.004. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
ACCEPTED MANUSCRIPT Myofascial origin of shoulder pain: a literature review
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Stanislav Sergienko BPT, Leonid Kalichman PT, PhD*
Department of Physical Therapy, Recanati School for Community Health Professions,
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Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel
*Corresponding author. Leonid Kalichman, Department of Physical Therapy, Recanati
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School for Community Health Professions, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel. Tel: 972-52-2787050;
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Fax: 972-8-6477683. E-mail address: [email protected]
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ACCEPTED MANUSCRIPT ABSTRACT Background: Shoulder pain is a common problem imposing a considerable burden on the affected person and society. Since interventions targeting traditional musculoskeletal
an alternative possible source of shoulder pain.
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conditions are usually only moderately effective, myofascial origin can be suggested as
Objectives: To examine current evidence associated with myofascial origin of shoulder
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pain, with emphasis on diagnosis, prevalence and treatment efficacy.
Methods: PubMed, Google Scholar and PEDro databases were searched from inception
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until December 2013 for terms relating to myofascial pain in the shoulder area. Results: Two studies showed a high reliability of the following diagnostic characteristics during palpation: presence or absence of the taut band, spot tenderness, jump sign, pain recognition and referred pain sensation. Three prevalence studies
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showed a significant greater number of active myofascial trigger points (MTrPs) on the painful shoulder side. Reduced muscle strength, accelerated muscle fatigue, inconsistent muscle activation pattern under load and reduced antagonist reciprocal inhibition were
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found in subjects with latent MTrPs in four observational studies. Six interventional studies demonstrated the effectiveness of dry needling, myofascial manipulation,
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ischemic compression, laser therapy and multimodal treatment. Conclusion: MTrPs in shoulder muscles is a common condition among patients with shoulder complaints and can be reliably diagnosed by palpation. The reviewed interventions seem to be effective in reducing pain, increasing range of motion and improving function of the painful shoulder. KEYWORDS Myofascial pain; Myofascial trigger points; Shoulder pain; Treatment; Review
2
ACCEPTED MANUSCRIPT INTRODUCTION Shoulder pain is a common musculoskeletal problem. It is the third most common cause of musculoskeletal consultation in primary care. Approximately 1% of adults annually
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consult a general practitioner with complaints of new shoulder pain (Urwin and others 1998). There are substantial disparities in reported 1-year prevalence of shoulder pain in the general population (4.7-46.7%), strongly influenced by various factors such as
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definition of shoulder disorders, including or excluding limited motion, age, gender and anatomic area (Luime and others 2004; Pope and others 1997). There is no clinical gold
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standard for defining shoulder pain. Shoulder complaints are usually identified as signs and symptoms in the deltoid, upper arm and scapular region, shoulder stiffness and reduced range of motion, often leading to limitations in daily activities (Pope and others 1997). Shoulder pain is widespread and imposes a considerable burden on the affected
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person and society. Swedish insurance data revealed that 18% of disability payments for musculoskeletal disorders was spent on neck and shoulder problems (van der Windt and others 2000). One of the most common causes of shoulder pain is subacromial
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impingement syndrome, comprising rotator cuff tendinopathy or subacromial bursitis. Infections, tumors and neural tissue pathologies are another possibility, but less
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common causes of shoulder pain (Bigliani and Levine 1997; Hawkins and Hobeika 1983; Koester and others 2005; Loitz and others 1999; Mayerhofer and Breitenseher 2004).
Since interventions targeting local subacromial conditions usually provide only
moderately effective treatment of shoulder complaints (Buchbinder and others 2003; Cummins and others 2009; Desmeules and others 2003; Dorrestijn and others 2009; Ekeberg and others 2009; Green and others 2003), alternative possible sources of
3
ACCEPTED MANUSCRIPT shoulder pain should be considered. Studies have found a high prevalence of muscles containing active and latent Myofascial Trigger Points (MTrPs) with high local mechanical pain sensitivity and referred pain in patients with chronic non-traumatic
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shoulder pain (Alburquerque-Sendin and others 2013; Bron and others 2011b; Fernandez-de-las-Penas and others 2012; Ge and others 2006; Ge and others 2008).
MTrPs are described as local points, highly sensitive to pressure causing characteristic
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referred sensations, pain, muscle dysfunction and in some cases even sympathetic hyperalgesia (Ge and others 2006; Simons and others 1999).
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MTrPs may be classified as active or latent. Active MTrPs are characterized by the presence of clinical pain and constant tenderness, preventing full lengthening and leading to weakening of the muscle. Diagnostically, active MTrPs refer to patientrecognized pain upon compression and mediate a local twitch response in muscle fibers
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when adequately stimulated. When compressed, active MTrPs produce referred motor phenomena and often autonomic phenomena, generally in its pain reference zone. In contrast, latent MTrPs are clinically quiescent with respect to spontaneous pain, and are
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painful only when palpated. A latent MTrP may have all the clinical characteristics of active MTrP, always with a taut band that increases muscle tension and restricts range
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of motion (Simons and others 1999). Another contribution of MTrPs to shoulder pain may be related to the weakening
and accelerated fatigability of affected muscles thus altering their activation patterns during shoulder movements (Celik and Yeldan 2011; Ge and others 2012; Ibarra and others 2011; Lucas and others 2010). Subacromial impingement syndrome can be associated with abnormal extrinsic mechanics including faulty posture, altered scapular or glenohumeral kinematics, increased anterior and superior humeral head translations,
4
ACCEPTED MANUSCRIPT decreased scapular posterior tipping, external rotation and upward rotation. Hence, weakness or fatigue of the muscles controlling these articulations may play a critical role in the development of subacromial impingement syndrome and shoulder pain
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(Michener and others 2003). Despite the possible importance of a myofascial component, reviews addressing the efficacy of interventions for disorders resulting in shoulder pain, stiffness and
Green and others 2003; Green and others 2005).
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disability rarely mention myofascial pain or MTrP therapy (Green and others 2000;
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The purpose of this review was to examine the current evidence associated with myofascial origin of shoulder pain, with emphasis on diagnosis, prevalence and treatment efficacy.
METHODS
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PubMed, Google Scholar and PEDro databases were searched from inception until December 2013, using a predefined search strategy. Databases were searched for the key words "shoulder", "pain", "myofascial", "trigger point" and various combinations.
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Titles and abstracts of all articles mentioning at least one of the key words were reviewed. Studies of any design or methodological quality, except case reports, dealing
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with MTrPs prevalence in the shoulder area, their effect on shoulder muscle function, clinical diagnosis and any kind of treatment were included. Articles were excluded if they were associated with myofascial pain after surgery, myofascial pain in cancer or fibromyalgia patients, myofascial trigger points not related to shoulder pain, injections or other pharmacological interventions for myofascial pain. Study protocol articles and articles without available full text were also excluded from the review. There were no
5
ACCEPTED MANUSCRIPT search limitations or language restrictions. The reference lists of all articles retrieved in full were also searched. The methodological quality of interventional studies was evaluated using the
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PEDro score checklist (http://www.pedro.org.au/). The PEDro scale considers two aspects of trial quality, the "internal validity" of the trial and whether the trial contains
validity" of the trial, or the size of the treatment effect. RESULTS
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sufficient statistical information to make it interpretable. It does not rate the "external
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The search strategy initially revealed 88 papers. Of them, 16 studies met the inclusion criteria and were included in this review.
Evaluation of MTrPs in shoulder muscles
Only two relevant studies dealing with the evaluation of MTrPs in shoulder muscles
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were found. One study investigated the test-retest reliability (three day interval, by the same expert) of MTrP diagnostic characteristics, such as taut band, spot tenderness, jump sign, pain recognition, referred pain and local twitch responses (Al-Shenqiti and
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Oldham 2005). Fifty-eight patients (31 males and 27 females, mean age 48.4 years) with rotator cuff tendonitis participated in the study. Kappa values between testing
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situations for the taut band, spot tenderness, jump sign and pain recognition were 1. Kappa values for referred pain ranged between 0.79 and 0.88 and for the local twitch response between 0.75 and 1, depending on the muscles under investigation. Kappa value for twitch response of supraspinatus and subscapularis could not be calculated as this sign was absent in all patients (Al-Shenqiti and Oldham 2005). In the second observational study, three experienced physical therapists bilaterally palpated the infraspinatus, anterior deltoid, and biceps brachii muscles for a total of 12
6
ACCEPTED MANUSCRIPT MTrPs (Bron and others 2007). The raters were blinded as to whether the shoulder of the subject was painful. Forty subjects (16 male and 24 female, 40 ± 11.5 years old) participated in the study, eight were asymptomatic and 32 had unilateral or bilateral
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shoulder pain. The most reliable features of MTrPs were the referred pain sensation and jump sign. The percentage of pair-wise agreement (PA) was ≥ 70% (range 63-93%) for referred pain sensation. For the jump sign, PA was ≥ 70% (range 67-77%). Finding a
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nodule in a taut band (PA = 45-90%) and eliciting a local twitch response (PA = 33-
100%) were shown to be least reliable. The highest inter-tester agreement regarding the
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presence or absence of MTrPs was found in the palpation of infraspinatus muscle (PA = 69-80%) (Bron and others 2007). The summary of studies on evaluation of MTrPs in shoulder muscles is presented in Table 1.
Prevalence of MTrPs in shoulder muscles and association with symptoms
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The number of MTrPs bilaterally in the infraspinatus muscles was assessed in an observational study of 21 females, 46.3 ± 4.2 years old, with chronic unilateral myofascial shoulder pain (Ge and others 2008). The number of MTrPs was significantly
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greater (p< 0.001) on the painful side (2.45 ± 0.13) than the non-painful side (1.37 ± 0.12). The number of active (2.31 ± 0.13) and latent (2.58 ± 0.13) MTrPs was similar on
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the painful side (P > 0.05), while on the non-painful side, there were only latent MTrPs (2.73 ± 0.13).
Another study evaluated the presence of MTrPs in the shoulder muscles of 72
subjects (22 males and 50 females, 43.9 ± 12.3 years old) with unilateral nontraumatic shoulder pain; the non-affected shoulder was examined as a control (Bron and others 2011b). The median number of muscles with MTrPs per subject was 6 for active and 4 for latent. Active MTrPs were most prevalent in the infraspinatus (77%) and the upper
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ACCEPTED MANUSCRIPT trapezius muscles (58%); latent MTrPs were most prevalent in the teres major (49%) and anterior deltoid muscles (38%). An additional study compared the number of MTrPs bilaterally in 10 shoulder
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muscles in two groups (Alburquerque-Sendin and others 2013). The shoulder impingement syndrome group consisted of 27 patients (13 males and 14 females, 35.6 ± 12.1 years old) with unilateral shoulder pain. The control group consisted of 20 healthy
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right-handed patients (9 males and 11 females, 37.0 ± 11.2 years old). Taking into
account both sides, the impingement group showed a greater number of MTrPs than the
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controls (p=0.01). The total number of muscles with MTrPs was higher on the involved side (4.7 ± 3.1) than on the dominant side in the control group (2.2 ± 2.8) (p=0.017), however no differences were detected with respect to the uninvolved side (3.2 ± 3.0). For latent MTrPs, no differences were found between sides (p>0.05), while the involved
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side presented a higher number (p=0.003) of active MTrPs (3.3 ± 3.0) compared with the uninvolved side (1.1 ± 2.2) (Alburquerque-Sendin and others 2013). Consecutive blue-collar or white-collar workers with chronic pain in the upper
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quadrant were investigated in another study (Fernandez-de-las-Penas and others 2012). In the blue-collar workers group that included 6 males and 10 females, 44 ± 13 years
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old, a mean of 6 ± 3 active and 10 ± 5 latent MTrPs were present. In the white-collar workers group that included 6 male and 13 females, 44 ± 14 years old, it was a mean of 6±4 active and 11±6 latent MTrPs. Active MTrPs in the upper trapezius, infraspinatus, levator scapulae, and extensor carpi radialis brevis muscles were most prevalent in both groups. No significant differences were found for the total number, the number of active or the number of latent MTrPs between groups (all p>0.05). Significant differences in referred pain areas between muscles were found (p<0.001) with the pectoralis major,
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ACCEPTED MANUSCRIPT infraspinatus, upper trapezius, and scalene muscle MTrPs showing the largest referred pain areas (p<0.01) (Fernandez-de-las-Penas and others 2012). The summary of studies on MTrPs prevalence in shoulder muscles is presented in Table 2.
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Effect of MTrPs on shoulder muscles function The study was designed to assess flexion and scaption strength in both shoulders using a hand-held dynamometer (Celik and Yeldan 2011). Group 1 included 28 healthy subjects
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(12 male and 16 female, 24.25 ± 4.9 years old) with at least two latent MTrPs located on the dominant side of the scapular muscles (upper and middle trapezius, supraspinatus,
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serratus anterior and rhomboids major and minor). Group 2 included 23 healthy subjects (18 males and 5 females, 23.52 ± 4.2 years old) without any MTrPs. No significant differences were found in muscle strength between dominant and non-dominant sides in both groups (p>0.05); both sides muscle strength in Group 1 was significantly lower
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than in Group 2 (p<0.05).
Another study recruited 12 healthy volunteers (8 males and 4 females, 27.4 ± 3.6 years old) with no signs or symptoms of musculoskeletal pain (Ge and others 2012).
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Each subject had at least one latent MTrP bilaterally in the upper trapezius muscle. Surface electromyographic (EMG) recordings and intramuscular EMG from latent
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MTrPs and non-MTrPs were obtained from the upper trapezius muscles during sustained isometric contractions. Intramuscular EMG from latent MTrPs showed an early decrease in mean power frequency and a significant decrease at the end of a fatiguing contraction compared with non-MTrPs (p<0.05). Surface EMG from muscle fibers close to latent MTrPs presented with an early increase in normalized root mean square amplitude. The increase was significantly higher than that of non-MTrPs at the end of a sustained isometric contraction (p<0.05). According to these findings, latent
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ACCEPTED MANUSCRIPT MTrPs are associated with an accelerated development of muscle fatigue, simultaneously overloading other active motor units (Ge and others 2012). An observational study employed surface EMGs to measure the timing of muscle
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activation onset of the upper and lower trapezius, serratus anterior, infraspinatus and middle deltoid muscles initially without load and with a light dumbbell in two groups (Lucas and others 2010). The MTrPs group included 28 subjects (16 males and 12
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females, 33.9 ± 11.4 years old) with at least one latent MTrP in the scapular positioning muscles on the dominant side, but not in the infraspinatus or middle deltoid. The control
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group included 14 subjects (7 males and 7 females, 35.6 ± 8.6 years old) with no latent MTrPs in any of the test muscles. The control group displayed a relatively stable sequence of muscle activation significantly different in timing and variability to that of the latent MTrPs group in all muscles except the middle deltoid (all p<0.05). The latent
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MTrPs group muscle activation pattern under load was inconsistent, the only common feature being early activation of the infraspinatus (Lucas and others 2010). Intramuscular and surface EMG activity between antagonist muscles was
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investigated in another study (Ibarra and others 2011). Fourteen healthy asymptomatic subjects (12 males and 2 females, 26 ± 6.9 years old) participated in a 2-trial study in
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which latent and non-MTrP were detected by palpation in the posterior deltoid muscle. This experiment consisted of 2 sessions with an intramuscular EMG needle electrode inserted into either a latent MTrP or a non-MTrP in the posterior deltoid muscle on the dominant side. The intramuscular EMG activity, but not surface EMG activity in the antagonist muscle, was significantly higher at rest and during shoulder flexion with latent MTrPs than non-MTrPs (p<0.05), signifying reduced antagonist reciprocal
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ACCEPTED MANUSCRIPT inhibition (Ibarra and others 2011). The summary of studies on the effect of MTrPs on shoulder muscles function is presented in Table 3. Treatment of MTrPs in shoulder muscles
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The search strategy revealed six studies dealing with myofascial pain treatment in the shoulder area. Characteristics and results of the reviewed intervention studies are shown in Tables 4 and 5, respectively.
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In a single-blinded within-subject design study, 14 patients with bilateral shoulder pain and active MTrPs in the infraspinatus muscles were evaluated (Hsieh and others
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2007). An MTrP in the infraspinatus muscle on a randomly selected side was dry needled; the contralateral side MTrPs was untreated and used as a control. Shoulder pain intensity was assessed by the Visual Analogue Scale (VAS). Internal rotation active and passive range of motion and pressure pain threshold (PPT) of the MTrPs was
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measured on both sides before and immediately after dry needling. All outcome measures significantly improved only on the treated side (p<0.01). Another study designed as a cross-over randomized control trial (RCT) evaluated
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the effect of 15 ischemic compression (IC) sessions on shoulder MTrPs in 59 patients with chronic shoulder pain (Hains and others 2010). A validated 13-question Shoulder
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Pain and Disability Index (SPADI) questionnaire was used to measure shoulder pain and functional impairment. After the first 15 treatments, the experimental group demonstrated a significant reduction in the SPADI score compared with the control group (p<0.05). The control group subjects also significantly reduced their SPADI scores after the cross-over (p<0.001). Another RCT assessed the effectiveness of multimodal treatment of MTrPs in patients with chronic shoulder pain (Bron and others 2011a). Thirty-four experimental
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ACCEPTED MANUSCRIPT group subjects received a 12 week treatment program. Manual compression of the MTrPs, manual stretching of the muscles and intermittent cold application with stretching was performed once a week by a physical therapist. Patients were instructed
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to perform muscle-stretching and relaxation exercises at home and received ergonomic recommendations and advice as to maintaining good posture. Thirty-one control group subjects remained on the waiting list for 3 months. Compared with the controls after 12
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weeks of treatment, the intervention group showed significant improvement according to the Disabilities of Arm, Shoulder and Hand (DASH) score and VAS (all p<0.05)
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(Bron and others 2011a).
The effectiveness of low-level laser therapy in treating shoulder MTrPs was evaluated in another RCT (Yamany and Salim 2011). Forty patients with unilateral shoulder pain and at least three MTrPs in the deltoid and/or upper trapezius muscles
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were randomly assigned into active and placebo laser groups. The subjects received 12 treatment sessions during a 4 week period, 3 sessions a week. A stretching and strengthening exercise program was performed daily under
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supervision in a clinic and at home for all patients in both groups. After 4 weeks of treatment, VAS and active range of motion significantly improved in both groups. PPT
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significantly increased only in the active laser group (all p < 0.0001). Compared with the placebo group, the active laser group made significant improvements in all outcomes (all p < 0.01) (Yamany and Salim 2011). A quasi-experimental study was designed to evaluate the effect of three fascial
manipulation sessions on chronic posterior brachial pain in 28 patients (Day and others 2009). Fascial manipulation involves applying local deep friction to specific areas over the deep fascia, identified as centers of coordination (Stecco 2004). The densification of
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ACCEPTED MANUSCRIPT fascia (lack of gliding between layers of fascia and between fascia and adjacent structures) was assumed to be associated with myofascial pain (Stecco and others 2013). VAS measurement of pain prior to the first session and after the third session was
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compared with a follow-up evaluation at three months. A mean pain reduction of 57% was obtained after the third session (p<0.0001) and remained without significant
changes (p>0.05) when reassessed after a three month follow-up (Day and others
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2009).
A cohort study assessed the short-term effect of IC for MTrPs on muscle strength,
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mobility, pain sensitivity, and disability in office workers and the effect on disability and general pain at 6-month follow-up (Cagnie and others 2013). Nineteen subjects completed the study and were included for the analyses. All the participants were righthanded office workers performing at least 4 hours of computer work and were
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answering the following criteria: (1) neck/shoulder pain or discomfort of > 30 days during the last year in the neck or shoulder region, (2) pain frequency of at least once a week, and (3) an intensity of pain of at least 2 on a scale from 0 to 10.
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Outcome measures were general neck and shoulder complaints on a Numeric Rating Scale (NRS), Neck Disability Index (NDI), passive neck flexion-extension and
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side flexion measured by inclinometer, neck and shoulder muscle strength measured by dynamometer, and PPT assessed by NRS and algometry. Subjects were tested at baseline (pre-control), after a control period of no treatment of 4 weeks (post-control), and after 4-week intervention training (post-treatment). At 6-month follow-up general neck/shoulder pain and disability were reassessed. All the subjects received 8 sessions of treatment (4 weeks, 2 times a week), consisting of IC on the 4 most painful MTrPs selected during the first testing session. IC
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ACCEPTED MANUSCRIPT consisted of pressure that was gradually increased until the subject experienced his/her highest tolerable pain and was sustained for one minute. The results showed a statistically significant decrease in general neck/shoulder
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pain at post-treatment (p =0.001) and at 6-month follow-up (p = 0.003) compared with pre-control and post-control. There was no significant main effect for NDI scores. PPP increased at post-treatment in all 4 treated MTrPs (p <0.001). There was a significant
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treatment (p<0.05) (Cagnie and others 2013).
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increase in range of motion and muscle strength from pre-control/post-control to post-
DISCUSSION
Two studies assessed the reliability of MTrPs clinical diagnosis in the shoulder region focusing on diagnostic characteristics during palpation. High reliability of presence or
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absence of the taut band, spot tenderness, jump sign, pain recognition and referred pain sensation demonstrated that MTrP palpation is a useful and reliable tool in diagnosing myofascial pain in patients with non-traumatic shoulder pain (Al-Shenqiti and Oldham
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2005; Bron and others 2007).
Prevalence studies have shown a significant greater number of active MTrPs on
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the painful shoulder side. In contrast, no significant difference was found in the number of latent MTrPs between painful and non-painful shoulder muscles. Active MTrPs were most prevalent in the infraspinatus, upper trapezius and levator scapulae muscles (Alburquerque-Sendin and others 2013; Bron and others 2011b; Ge and others 2008). Surprisingly, no significant difference was found in the total number of shoulder MTrPs between white-collar and blue-collar workers (Fernandez-de-las-Penas and others
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ACCEPTED MANUSCRIPT 2012). Obviously, type of work is not a key factor in upper quadrant MTrPs development. Other contributing factors should be investigated in future studies. The effect of MTrPs on shoulder muscle function was evaluated in four
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observational studies. Reduced muscle strength, accelerated muscle fatigue and simultaneous overloading active motor units were found in subjects with latent MTrPs (Celik and Yeldan 2011; Ge and others 2012). In addition, two EMG studies assessing
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the interaction between shoulder muscles and latent MTrP showed an inconsistent
muscle activation pattern under load and reduced antagonist reciprocal inhibition (Ibarra
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and others 2011; Lucas and others 2010). These findings may have an important clinical implication for diagnosis and treatment of disorders associated with abnormal shoulder muscle function, i.e. subacromial or subcoracoid impingement syndromes, rotator cuff or biceps tendinopathy, etc.
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The association between prevalence of active MTrPs and shoulder pain and the influence of MTrPs on shoulder muscle function emphasizes the importance of evaluating myofascial pain in every case of shoulder pain. We feel that myofascial pain
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evaluation should become routine when evaluating shoulder pain. Reviewed studies on the treatment of shoulder myofascial pain, demonstrated the
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effectiveness of dry needling, myofascial manipulation, IC, laser therapy and multimodal treatment that included manual MTrPs compression, manual muscles stretching, cold application, home exercises and ergonomic recommendations. Most studies used VAS of pain intensity as an outcome measure, usually combined with range of motion, functional scales or PPT (Bron and others 2011a; Day and others 2009; Hains and others 2010; Hsieh and others 2007; Yamany and Salim 2011). Since significant electromyographic changes were found in muscles affected by MTrPs (Ge
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ACCEPTED MANUSCRIPT and others 2012; Ibarra and others 2011; Lucas and others 2010), EMG recordings could be used as additional quantitative outcome measure in future MTrPs treatment studies.
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CONCLUSIONS Presence of MTrPs in shoulder muscles is a common condition among patients with
shoulder complaints. Therefore, the myofascial component should be considered as a
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possible primary or secondary source of shoulder pain during clinical examination.
The reviewed interventions for shoulder muscle MTrPs seem to be effective in
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reducing pain, increasing range of motion and improving function of the painful shoulder. Additional studies are needed to identify the contributing factors and causes of MTrPs development in the shoulder area in order to establish preventive strategies for
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these conditions.
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ACCEPTED MANUSCRIPT ACKNOWLEDGEMENTS
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The authors thank Mrs Phyllis Curchack Kornspan for her editorial services.
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Bron C, Dommerholt J, Stegenga B ,Wensing M, Oostendorp RA. 2011b. High prevalence of shoulder girdle muscles with myofascial trigger points in patients with shoulder pain. BMC Musculoskelet Disord 12:139.
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Bron C, Franssen J, Wensing M, Oostendorp RA. 2007. Interrater reliability of palpation of myofascial trigger points in three shoulder muscles. J Man Manip
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Buchbinder R, Green S, Youd JM. 2003. Corticosteroid injections for shoulder pain. Cochrane Database Syst Rev(1):CD004016.
Cagnie B, Dewitte V, Coppieters I, Van Oosterwijck J, Cools A, Danneels L. 2013. Effect of ischemic compression on trigger points in the neck and shoulder muscles in office workers: a cohort study. J Manipulative Physiol Ther 36(8):482-9.
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ACCEPTED MANUSCRIPT Celik D, Yeldan I. 2011. The relationship between latent trigger point and muscle strength in healthy subjects: a double-blind study. J Back Musculoskelet Rehabil 24(4):251-6.
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Cummins CA, Sasso LM, Nicholson D. 2009. Impingement syndrome: temporal outcomes of nonoperative treatment. J Shoulder Elbow Surg 18(2.172-7:(
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chronic shoulder pain--anatomical basis and clinical implications. J Bodyw Mov Ther 13(2):128-35.
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Desmeules F, Cote CH, Fremont P. 2003. Therapeutic exercise and orthopedic manual therapy for impingement syndrome: a systematic review. Clin J Sport Med 13(3):176-82.
Dorrestijn O, Stevens M, Winters JC, van der Meer K, Diercks RL. 2009. Conservative
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or surgical treatment for subacromial impingement syndrome? A systematic review. J Shoulder Elbow Surg 18(4):652-60. Ekeberg OM, Bautz-Holter E, Tveita EK, Juel NG, Kvalheim S, Brox JI. 2009.
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Subacromial ultrasound guided or systemic steroid injection for rotator cuff disease: randomised double blind study. BMJ 338:a3112.
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Fernandez-de-las-Penas C, Grobli C, Ortega-Santiago R, Fischer CS, Boesch D, Froidevaux P, Stocker L, Weissmann R, Gonzalez-Iglesias J. 2012. Referred pain from myofascial trigger points in head, neck, shoulder, and arm muscles reproduces pain symptoms in blue-collar (manual) and white-collar (office) workers. Clin J Pain 28(6):511-8. Ge HY, Arendt-Nielsen L, Madeleine P. 2012. Accelerated muscle fatigability of latent myofascial trigger points in humans. Pain Med 13(7):957-64.
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ACCEPTED MANUSCRIPT Ge HY, Fernandez-de-las-Penas C, Arendt-Nielsen L. 2006. Sympathetic facilitation of hyperalgesia evoked from myofascial tender and trigger points in patients with unilateral shoulder pain. Clin Neurophysiol 117(7):1545-50.
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Ge HY, Fernandez-de-Las-Penas C, Madeleine P, Arendt-Nielsen L. 2008. Topographical mapping and mechanical pain sensitivity of myofascial trigger points in the infraspinatus muscle. Eur J Pain 12(7):859-65.
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Green S, Buchbinder R, Glazier R, Forbes A. 2000. Interventions for shoulder pain.
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Hains G, Descarreaux M, Hains F. 2010. Chronic shoulder pain of myofascial origin: a randomized clinical trial using ischemic compression therapy. J Manipulative Physiol Ther 33(5):362-9.
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Hawkins RJ, Hobeika PE. 1983. Impingement syndrome in the athletic shoulder. Clin Sports Med 2(2):391-405.
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Hsieh YL, Kao MJ, Kuan TS, Chen SM, Chen JT, Hong CZ. 2007. Dry needling to a key myofascial trigger point may reduce the irritability of satellite MTrPs. Am J Phys Med Rehabil 86(5):397-403.
Ibarra JM, Ge HY, Wang C, Martinez Vizcaino V, Graven-Nielsen T, Arendt-Nielsen L. 2011. Latent myofascial trigger points are associated with an increased antagonistic muscle activity during agonist muscle contraction. J Pain 12(12):1282-8.
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conservative and operative treatment]. Unfallchirurg 102(11):870-87. Lucas KR, Rich PA, Polus BI. 2010. Muscle activation patterns in the scapular
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Myofascial Trigger Points. Clin Biomech (Bristol, Avon) 25(8):765-70.
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JA .2004 .Prevalence and incidence of shoulder pain in the general population; a systematic review. Scand J Rheumatol 33(2):73-81.
Mayerhofer ME, Breitenseher MJ. 2004. [Impingement syndrome of the shoulder]. Radiologe 44(6):569-77.
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Pope DP, Croft PR, Pritchard CM, Silman AJ. 1997. Prevalence of shoulder pain in the community: the influence of case definition. Ann Rheum Dis 56(5):308-12.
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Simons DG, Travell JG, Simons LS. 1999. Travell and Simons’ Myofascial Pain and Dysfunction: The Trigger Point Manual. Baltimore, MD: Williams & Wilkins.
Stecco A, Gesi M, Stecco C, Stern R. 2013. Fascial components of the myofascial pain syndrome. Curr Pain Headache Rep 17(8):352.
Stecco L. 2004. Fascial Manipulation. Padova: Piccin. Urwin M, Symmons D, Allison T, Brammah T, Busby H, Roxby M, Simmons A, Williams G. 1998. Estimating the burden of musculoskeletal disorders in the
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ACCEPTED MANUSCRIPT community: the comparative prevalence of symptoms at different anatomical sites, and the relation to social deprivation. Ann Rheum Dis 57(11):649-55. van der Windt DA, Thomas E, Pope DP, de Winter AF, Macfarlane GJ, Bouter LM,
review. Occup Environ Med 57(7):433-42.
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Silman AJ. 20 .00Occupational risk factors for shoulder pain: a systematic
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Myofascial Trigger Points of Shoulder Pain. World Applied Sciences Journal
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Table 1. Summary of studies on evaluation of MTrPs in shoulder muscles. Design
Participants
Shenqiti
test-retest
rotator cuff
reliability, three
tendonitis
Mean
(male/female)
age
58 (31/27)
48.4
& Oldham day interval, by the
8 asymptomatic and
reliability between
32 with unilateral or
three experienced
bilateral shoulder
physical therapists
pain
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2007
Inter-tester
40 (16/24)
40 ± 11.5
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Bron et al
same expert
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2005
Kappa value
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Al-
N
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Inclusion Criteria
Outcome
Results
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Study
Kappa values for the taut band, spot tenderness,
jump
sign
and
pain
recognition were 1. Kappa values for referred pain ranged between 0.79 and 0.88 and for the local twitch response between 0.75 and 1
Percentage of
The most reliable features of MTrPs
pair-wise
diagnosis were referred pain sensation
agreement
(PA ≥ 70%, range 63-93%) and jump
(PA)
sign (PA ≥ 70%, range 67-77%)
PA - Percentage of pair-wise agreement, MTrPs – myofascial trigger points.
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Table 2. Summary of MTrPs prevalence in shoulder muscles studies. Participants N
Mean
(male/female)
age
Chronic unilateral
21
46.3 ±
The number of
shoulder pain
(0/21)
4.2
MTrPs bilaterally in
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Ge et al 2008
Results
nontraumatic
(22/50)
shoulder pain
43.9 ± 12.3
0.001) on the painful side (2.45 ± 0.13) than the non-
the infraspinatus
painful side (1.37 ± 0.12). The number of active
muscles
(2.31 ± 0.13) and latent (2.58 ± 0.13) MTrPs was
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72
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unilateral
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Bron et al 2011
The number of MTrPs was significantly greater (p<
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Inclusion Criteria
Outcome
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Study
similar on the painful side (P > 0.05), while on the non-painful side only latent MTrPs were found (2.73 ± 0.13)
The presence of
The median number of muscles with MTrPs per
MTrPs in the
subject was 6 for active and 4 for latent. Active
shoulder muscles
MTrPs were most prevalent in the infraspinatus (77%) and the upper trapezius muscles (58%); latent MTrPs were most prevalent in the teres major (49%) and anterior deltoid muscles (38%)
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shoulder
27
35.6 ±
The number of
The impingement group showed a greater number of
Sendin et al
impingement
(13/14)
12.1
MTrPs bilaterally in
MTrPs than the controls (p=0.01). The total number
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syndrome with
shoulder muscles in
of muscles with MTrPs was higher on the involved
unilateral shoulder
two groups
control group (2.2 ± 2.8) (p=0.017), no differences
37.0 ±
handed patients
(9/11)
11.2
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las-Penas et al
workers with
(6/10)
2012
chronic pain in the
44 ±
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blue-collar
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Fernandez-de-
white-collar workers with
19
were detected with respect to the uninvolved side
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20
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healthy right-
upper quadrant
side (4.7 ± 3.1) than on the dominant side in the
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pain
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Alburquerque-
44 ±
(3.2 ± 3.0). For latent MTrPs, no differences were found between sides (p>0.05), while the involved side presented a higher number (p=0.003) of active MTrPs (3.3 ± 3.0) compared with the uninvolved side (1.1 ± 2.2)
The number of
A mean of 6 ± 3 active and 10 ± 5 latent MTrPs were
active and latent
present in the blue-collar workers group, compared to
MTrPs in both
6±4 active and 11±6 latent MTrPs in the white-collar
groups.
group. No significant differences were found for the
The referred pain
total number, the number of active or the number of
areas (drawn on
latent MTrPs between groups (all p>0.05).
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(6/13)
14
upper quadrant
anatomic maps,
Significant differences in referred pain areas between
digitized, and
muscles were found (p<0.001) with the pectoralis
measured)
major, infraspinatus, upper trapezius, and scalene
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chronic pain in the
muscle MTrPs showing the largest referred pain
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areas (p<0.01).
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MTrPs – myofascial trigger points.
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Table 3. Summary of studies on the effect of MTrPs on shoulder muscles function. Participants Inclusion Criteria
Outcome N
Mean
(male/female)
age
Results
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Study
Healthy subjects with ≥
28
24.25
flexion and scaption strength in
Yeldan
latent MTrPs located on
(12/16)
± 4.9
both shoulders using a hand-
2011
the dominant side of the
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Celik &
held dynamometer
scapular muscles 23
23.52
without any MTrPs
(18/5)
± 4.2
Ge et al
Healthy volunteers with
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2012
≥one latent MTrP
(8/4)
trapezius muscle
muscle strength between dominant and nondominant sides in both groups (p>0.05). Both sides muscle strength in group with MTrPs was significantly lower than in group without MTrPs (p<0.05).
27.4 ± Surface and intramuscular EMG Intramuscular EMG from latent MTrPs from latent MTrPs and non-
showed an early decrease in mean power
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3.6
MTrPs from the upper trapezius frequency and a significant decrease at the
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bilaterally in the upper
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Healthy subjects
No significant differences were found in
muscles during sustained isometric contractions
end of a fatiguing contraction compared with non-MTrPs (p<0.05). Surface EMG from muscle fibers close to latent MTrPs presented with an early
27
ACCEPTED MANUSCRIPT
increase in normalized root mean square amplitude. The increase was significantly
RI PT
higher than that of non-MTrPs at the end of a sustained isometric contraction (p<0.05)
≥ One latent MTrP in
28
33.9 ±
Timing of muscle activation
al 2010
the scapular positioning
(16/12)
11.4
onset of the upper and lower
M AN U
SC
Lucas et
muscles on the
trapezius, serratus anterior,
dominant side 14 (7/7)
MTrPs
35.6 ±
muscles with and without light
8.6
load
Healthy asymptomatic
14
26 ±
and
subjects
(12/2)
6.9
significantly
of
muscle
different
in
activation
timing
and
in all muscles except the middle deltoid (all p<0.05)
activity of latent MTrP or a
surface EMG activity in the antagonist
non-MTrP in posterior deltoid
muscle, was significantly higher at rest and
muscle (antagonist) during
during shoulder flexion with latent MTrPs
AC C
2011)
sequence
Intramuscular and surface EMG The intramuscular EMG activity, but not
EP
(Ibarra
others
stable
infraspinatus and middle deltoid variability to that of the latent MTrPs group
TE D
Controls with no latent
The control group displayed a relatively
shoulder flexion
than non-MTrPs (p<0.05)
MTrPs – myofascial trigger points, EMG – electromyography.
28
ACCEPTED MANUSCRIPT
Table 4. Characteristics of the reviewed shoulder myofascial pain treatment studies. Experimental Group Mean
Inclusion
(male/female)
Age
Criteria
14 (8/6)
Intervention
60.2±13.2 Bilateral
1 session of
The same 14
subjects from the
shoulder pain +
MTrP dry
2007
Infraspinatus
needling
M AN U
et al
MTrPs
3 sessions of
et al
posterior
fascial
2009
brachial pain 41 (21/20)
26.7
46.5±8.8
Shoulder pain
TE D
Chronic
Hains
28 (13/15)
for at least the
2010
past 3 months
AC C
et al
Age
Inclusion
Intervention
Criteria
60.2±13.2 Bilateral shoulder pain +
treatment group
Infraspinatus
used as a control
MTrPs
-
-
18 (5/13)
45.6±7.4
-
-
-
manipulation
15 sessions of
Shoulder pain
15 sessions of
ischemic
for at least the
ischemic
compression on
past 3 months
compression on
EP
Day
N (male/female)
RI PT
Hsieh
N
SC
Study
Control Group
shoulder muscle
cervical muscle
MTrPs (once a
MTrPs (once a
week)
week)
29
ACCEPTED MANUSCRIPT
Table 4. Characteristics of the reviewed shoulder myofascial pain treatment studies (cont).
al
(13/21)
42.8±11.7
2011
Unilateral
12 week program of
31
nontraumatic
manual MTrPs
shoulder pain for
compression and muscles
at least 6 months
stretching, cold
45.0±13.2 Unilateral
(8/23)
RI PT
34
SC
Bron et
application, stretching and
M AN U
relaxation exercises at
Remained on
nontraumatic
the waiting list
shoulder pain
for 3 months
for at least 6 months
home, ergonomic
recommendations
(12/8)
2011
32.6±2.79
Unilateral
12 sessions of laser during
shoulder pain with at least three
20
34.8±7.22 Unilateral
12 sessions of
a 4 week period, combined (10/10)
shoulder pain
placebo laser
with an exercise program
with at least
during a 4
three MTrPs
week period,
AC C
MTrPs
TE D
et al
20
EP
Yamany
combined with an exercise program
Cagnie
19
39.47±8.32 Office workers
8 sessions of IC during a 4
-
-
-
-
30
ACCEPTED MANUSCRIPT
2013
(3/16)
with mild neck
week period, applied on 4
and shoulder
most painful MTrPs
complaints for
identified during
more than 30 days examination
SC
during the last
RI PT
et al
AC C
EP
TE D
MTrPs – myofascial trigger points; IC – ischemic compression
M AN U
year
31
ACCEPTED MANUSCRIPT
Table 5. Results of the reviewed should myofascial pain treatment studies.
5/10
al 2007
Outcome
Short Term
Long Term (Follow-up)
Shoulder IR AROM
Increase in treatment side (p <0.01)
-
Shoulder IR PROM
Increase in treatment side (p <0.01)
-
SC
Hsieh et
PEDro
Infraspinatus MTrPs PPT Increase in treatment side (p <0.01)
M AN U
Study
RI PT
Findings
-
Reduction in treatment side (p<0.001)
Pain intensity by VAS
Mean pain reduction of 57% after 3rd
The benefit did not significantly change at the
2009
session (p<0.0001)
three month follow-up (p>0.05)
Hains et
Reduction in experimental group SPADI
Reduction in experimental group SPADI scores
scores compared with controls (p<0.05)
after 6 months (p<0.001). Reduction in control
9/10
SPADI score
EP
al 2010
3/10
-
group SPADI scores after crossover (p<0.001)
AC C
Day et al
TE D
Pain intensity by VAS
32
ACCEPTED MANUSCRIPT
Table 5. Results of the reviewed should myofascial pain treatment studies (cont). DASH score
group compared with controls (p<0.05)
RI PT
2011
6/10 VAS score for current pain,
Reduction in experimental group VAS scores
average and most severe
compared with the controls (all p<0.05)
et al 2011
VAS
M AN U
pain during the past 7 days Yamany
-
-
SC
Bron et al
Functional improvement in experimental
VAS and AROM significantly improved in
8/10 Shoulder Flex/Abd AROM
both groups, PPT significantly increased only in the active laser group (all p < 0.0001)
PPT
-
TE D
Compared with placebo, the active laser group showed significant improvements in all
General neck/shoulder
et al
complaints by NRS
NRS significantly decreased at post treatment
AC C
Cagnie
EP
outcomes (all p < 0.01) At 6-month follow-up NRS was still
(p = 0.001) compared with
significantly lower compared with
precontrol/postcontrol
precontrol/postcontrol (p = 0.003)
NDI
No significant difference (p = 0.079)
No significant difference (p = 0.079)
Cervical PROM
Significant increase in flexion-extension
2013
-
33
ACCEPTED MANUSCRIPT
(p = 0.003) and side flexion (p ≤ .001) compared with precontrol/postcontrol Significant increase in PPT compared with precontrol/postcontrol (p<0.001)
All strength scores significantly increased
-
-
SC
Muscle Strength
RI PT
PPT
(p<0.05)
M AN U
compared with precontrol /postcontrol
IR AROM - Internal Rotation Active Range of Motion; IR PROM - Internal Rotation Passive Range of Motion; PPT - Pressure Pain Threshold; VAS - Visual Analog Sale; SPADI - The Shoulder Pain and Disability Index; DASH - The Disabilities of Arm, Shoulder and
EP AC C
NDI - Neck Disability Index.
TE D
Hand; Flex/Abd AROM - Flexion/Abduction Active Range of Motion; MTrPs – myofascial trigger points; NRS - Numeric Rating Scale;
34