{999B206B-BA2D-4F85-B869-6DE0133D9FCB}18

7/28/2019 {999B206B-BA2D-4F85-B869-6DE0133D9FCB}18

1/17

4

Work related neckshoulder pain: a review

on magnitude, risk factors, biochemical

characteristics, clinical picture and

preventive interventions

Britt Larsson MD, PhDSenior Physician

Division of Rehabilitation Medicine, Department of Neuroscience and Locomotion, Faculty of Health Sciences,

and Pain and rehabilitation centre, University Hospital, 581 85 Linkoping, Sweden

Karen Sgaard MSc, PhDSenior Researcher

National Research Centre for the Working Environment, Lers Parkalle 105, DK-2100 Copenhagen, Denmark

Lars Rosendal* MSc, PhDSenior Clinical Research Associate

Cyncron, Department of Clinical Operations, P.O. Box 130, Datavej 24, DK-3460 Birkerd, Denmark

The purpose of this review is to scrutinize the physiology of neckshoulder pain and trapeziusmyalgia based on the most recent scientific literature. Therefore, systematic literature searcheshave been conducted. Occurrence of neckshoulder pain, risk factors for development ofneckshoulder pain, and its work-relatedness are addressed. Furthermore, the latest informa-

tion on the biochemical milieu within healthy and painful neckshoulder muscles is reviewed.Finally diagnosis of and intervention for neck and shoulder pain are discussed.

Key words: algesic; biopsy; human; intervention; metabolism; microdialysis; muscle; myalgia;pain; neck; review; risk factor; shoulder; trapezius; work-related.

Musculoskeletal disorders comprise one of the most common and costly public healthissues in Europe and North America1,2, and the cost in the Nordic countries andHolland has been estimated to encompass 0.52% of the GNP.3 Among these

* Corresponding author. Tel.: 45 70 20 20 58; Fax: 45 70 20 20 57.

E-mail address: [email protected] (L. Rosendal).

1521-6942/$ - see front matter 2007 Elsevier Ltd. All rights reserved.

Best Practice & Research Clinical RheumatologyVol. 21, No. 3, pp. 447463, 2007

doi:10.1016/j.berh.2007.02.015

available online at http://www.sciencedirect.com
mailto:[email protected]://www.sciencedirect.com/http://www.sciencedirect.com/mailto:[email protected]

7/28/2019 {999B206B-BA2D-4F85-B869-6DE0133D9FCB}18

2/17

disorders, persistent neckshoulder pain, including myalgia, is one of the commonest.For several decades well-defined work-related physical and psychosocial factors havebeen shown to be associated with onset or worsening of pain in this region. In spite ofabundant epidemiological knowledge, there is little to indicate that the incidence ofneckshoulder pain is diminishing. The pathophysiology of myalgia in this region hasbeen reviewed in a number of papers, with the conclusion that there are multiple

possible mechanisms.46 However, whether local muscular processes provide anexplanation for this kind of pain is often questioned.7 In the case of chronic neckshoulder pain, in particular, the muscular component is often considered uncertain.However, recently a relatively large number of studies using methods such as musclebiopsy and microdialysis have opened up new possibilities for elucidating the role ofperipheral factors and changes in the biochemical milieu in muscle in the developmentand maintenance of pain and disorders.

Research in the field of work-related myalgia often concerns the plausible connec-tion between muscular activity and muscle damage.6 This relationship, as well asknowledge of pathomechanisms, are partly but not sufficiently elucidated.8,9

Accurate and, ideally, standardized diagnosis of neck and shoulder myalgia is a pre-requisite for adequate individual ergonomic interventions. Furthermore, preventionmust rely on scientifically based knowledge regarding risk factors as well as the pos-sible pathomechanisms behind the development of neck pain.

This review addresses the occurrence of neckshoulder pain and trapezius myalgia,and risk factors for the development of these complaints. Furthermore, the signifi-cance of histological and biochemical alterations underlying pain, diagnostic possibili-ties, and interventional aspects of neckshoulder pain will be reviewed.

OCCURRENCE OF WORK-RELATED NECKSHOULDER DISORDER

There is a vast amount of epidemiological literature dealing with work-relatedneckshoulder disorders as a major health problem in many occupations. Still, thework-relatedness in the sense of a well-established doseresponse relationship ora calculated etiological fraction is poorly documented. This is due to several factorspresenting varying degrees of difficulty for a straightforward interpretation. First ofall, the term neckshoulder disorders covers a broad spectrum ranging from self-reported pain to a relatively well-defined clinical diagnosis. Therefore, incidence andprevalence of neckshoulder disorders are difficult to compare across studies and

countries. In the Finnish population the prevalence of neck pain has in the last two de-cades shown a steady increase and is the second most frequent musculoskeletalcomplaint.10 In the working population in general, the estimated prevalence ofupper-extremity symptoms is in the range 2030%.1 In a Canadian general populationsurvey the 6-month prevalence of neck pain was more than 50% among all adults.11

Women more often than men experience neck pain and develop persistent pain,and most individuals with neck pain do not experience complete resolution of theirsymptoms and disability.11 Within certain occupations the prevalence is even higherthan in the general population; among Danish computer users the 12-month preva-lence of more that 7 days with neck pain was approximately 45%.12 The incidence

of neck cases was 25% for women and 15% for men. In addition, those who reportedprevious symptoms were more likely to also develop symptoms in the follow-up pe-riod.12 Prevalence is highest when neck symptoms are quantified by self-reportedduration, frequency, and intensity. The prevalence decreases when symptoms are to

448 B. Larsson et al

7/28/2019 {999B206B-BA2D-4F85-B869-6DE0133D9FCB}18

3/17

be confirmed by physical examination findings. Thus, in a study of elderly female com-puter-users in EU countries, it was found that for as many as 60% of those with self-reported neck symptoms of a certain duration and intensity, a clinical examinationcould confirm one or more diagnoses, with trapezius myalgia (38%), tension neck syn-drome (17%), and cervicalgia (17%) being the most frequent.13

For the individual, the consequences of neckshoulder pain may range from minor

episodes of short duration with limited activity, through recurrent episodes withdiminished work capacity and performance, to severe and disabling episodes orchronic disability. Therefore, for society the economical consequences similarly rangefrom short-term sick leave, through recurrent long-term sick-leave periods, to earlyretirement and/or disability pension.

Risk factors identified in the scientific literature

In 2001 a large review presented a state-of-the-art overview scrutinizing the available

documentation on possible risk factors for work-related upper-extremity disorders.14

The conclusion stated that strong evidence was found for a causal relationship be-tween neck disorders and highly repetitive work, forceful exertions, high level of staticcontractions, prolonged static loads and extreme postures, as well as combinations ofthese factors. There was insufficient evidence for vibration as a risk factor for neckdisorder.

Literature search, 20002006

In the present review it was decided to follow up on this earlier review with a system-atic search of the newest epidemiological literature to reveal whether new evidencehad emerged regarding risk factors for upper-extremity disorders. The search wasperformed in OSHROM, MEDLINE, EMBASE and Cochrane (CDSR). For details seeAppendix 1.

The search was conducted as a combination of four sets of keywords, and resultswere restricted to review papers published from 2000 to 2006 in the English language.This resulted in 156 review papers that were scrutinized to include only systematicreviews with a reproducible search method, a quality estimation and objective criteriafor defining sufficient evidence for a risk factor. This procedure resulted in ten reviews

primarily based on epidemiological evidence and considering both disorders confirmedby clinical examinations as well as symptoms described as disorders, pain, decreasedwork ability or performance, etc. Conclusions on the major risk factors are presentedas follows.

Identified risk factors

Gender

Individual factors are not considered in this review, with just one exception; gender

seems to play a prominent role, since the prevalence of pain in the upper extremityis much higher among women than men.1517 This is the case even when adjustingfor confounders such as age and seniority. The difference may be explained by manyfactors, but one explanation could be that womens jobs, more often than mens,

Work related neckshoulder pain 449
http://-/?-http://-/?-

7/28/2019 {999B206B-BA2D-4F85-B869-6DE0133D9FCB}18

4/17

involve work tasks with static load on the neck muscles, high repetitiveness, low con-trol and high mental demands that are possible risk factors for neckshoulder pain.

Repetitive movements

Malchaire et al found that 75% of the studies reviewed demonstrated a significant

relationship between repeated movements and upper extremity disorders in general,whereas van der Windt et al found a consistent relationship specifically betweenneckshoulder pain and repeated movements.18,19 However, it was not possible tofind evidence of a detailed doseresponse relation between specific work tasks andthe development of specific disorders. All in all the most recent literature reviews con-firm the strong evidence found in the National Research Council (NRC) survey forrepetitive movements.

High force demands

Very few work situations demand high force performed directly by neckshouldermuscles. However, forceful manipulation with the hands often requires a high degreeof stabilization in the neckshoulder area. Ariens et al found some evidence for a cor-relation between the work-related force requirements in the arms and neckshoulderpain, as well as between heavy lifting and neckshoulder pain.20 Malchaire et al furtherfound sufficient evidence for a linkage between forceful hand work and both hand/wrist and neckshoulder disorders.18

Work posture

Work posture as a risk factor for neck disorders involves both duration of constrainedpostures, as well as awkward or extreme postures involving both neck and arm.Malchaire et al found evidence for awkward posture as a risk factor for neckshoulderdisorder.18 Likewise, Ariens et al found some evidence for a causal relation betweenneck disorders and sedentary work for more than 5 hours a day, as well as workdemanding bending and twisting of the upper spine.20 Both Ariens et al and Walker-Bone et al found that working with the arms lifted above shoulder level was a well-documented risk factor for neckshoulder disorder.16,20

Vibration

Vibration is typically found in work with hand tools or machines. In the NRC reportevidence was found for vibration as a risk factor for muscle disorders in general.14 Therecent literature survey does not support this clear picture. While Malchaire et alfound no relationship between vibration and shoulder or hand disorders18, van derWindt et al reported a consistent association with shoulder disorder19, while Ariensconcluded that there was some evidence.20

Computer work

The NRC review concluded that there was evidence for an increased risk for devel-

opment of upper-extremity disorders among computer users.14

It was suggestedthat this could be due to constrained postures, constant force and highly repetitivemovements as well as psychosocial factors such as time constraints and high quantita-tive demands. This conclusion is supported by the prevailing literature on sustained


7/28/2019 {999B206B-BA2D-4F85-B869-6DE0133D9FCB}18

5/17

activity of low-threshold motor units during low-force static or repetitive muscle ten-sion in trapezius as well as the forearm muscle.2125

Only a few reviews have been done since 2000 regarding the documentationfor computer work and symptoms from the upper extremities. A single review hasfocused on temperature and disorders, since cold hands and forearms are oftenreported symptoms among computer users.26 However, no support was found for

a connection between temperature changes and disorders among computer users.Gerr et al focused on the association between neck disorders and work postures

and duration of computer use measured as hours per day or week.27 The review con-cluded that there is evidence for work posture as a risk factor for the development ofdisorders. Specifically, the keyboard position below elbow height and support underthe forearms were associated with a reduced risk of developing neckshoulder disor-ders. Even though it was not possible to specify a doseresponse relationship,evidence was found for duration of computer work as a riskfactor for neckshoulderdisorder, as has also been confirmed in recent studies.27,28

Veiersted et al focused on a possible connection between computer use and clin-

ically diagnosed disorders in neck, shoulder and arms, and is thus narrower in scopethan the reviews on symptoms in general.29 They found that there was limited evi-dence for a causal relationship between computer work, mouse use or keyboarduse, and this rather strict definition of neck disorders that does not consider diagnosessuch as, for instance, trapezius myalgia.29

Psychosocial factors

The NRC report showed documentation for a causal relationship between work-related stress and high demands, and disorders in the upper extremity.16 Only a few

newer overviews add to this. There is some evidence for a relationship between dis-orders and high quantitative demands, lack of support from colleagues, low job controland low influence.30 In two other reviews, evidence for a relation between mentalstress at work and disorders was also demonstrated.18,31 In addition, a relationshipbetween high quantitative and qualitative demands at work and disorders was evident.However, there was insufficient evidence to evaluate the relationship between disor-ders and low control, influence on own job situation, lack of support from colleaguesand superiors, general unsatisfactory job content. All in all, the limited amount of lit-erature focusing on causal relationships between psychosocial factors and disordersmakes it difficult to estimate the influence of these factors and how they may interact

with the biomechanical and individual factors.

MUSCLE NOCICEPTION

Neurophysiological studies have indicated that small-diameter, slowly conducting affer-ent nerve fibres from skeletal muscle have to be excited in order to elicit pain. A highproportion of these fibres terminate in free nerve endings with nociceptive proper-ties.32 Nociceptors are sensitive to chemical substances released from damaged oroverloaded cells and excessive tissue deformation.33 Nociceptors have been shown

to respond to several algesic substances such as bradykinin, serotonin, and prostaglan-din, to name a few.34 Administration ofany of these substances, alone or in combina-tion, results in excitation of nociceptors33 and/or peripheral sensitization. A sensitizednociceptor has a lowered threshold for activation and can thus be activated by stimuli


7/28/2019 {999B206B-BA2D-4F85-B869-6DE0133D9FCB}18

6/17

which are normally innocuous.33 Sensitization is often accompanied by an increase inthe sensitive area.33 Different sensitization processes can occur in the central nervoussystem. Central sensitization and spreading of pain is widely discussed, and is verylikely to influence the clinical symptoms and the course of neck myalgia, but is beyondthe aim of this chapter to review. Most research on muscle pain has been conductedon animals; however, this review will primarily focus on human studies of neck and

shoulder myalgia, for which the frequently affected trapezius muscle often serves asa model muscle.

MORPHOLOGICAL AND BIOCHEMICAL STUDIES OF MYALGIA

During recent years, several studies on biochemical and morphological processes inmyalgic human muscle have been published and will be the focus in this section.

Literature search

A systematic literature search was made in MedLine, Science Citation Index andEMBASE. The following combinations of search words were used: (1) trapezius,biopsy, (2) neck, muscle, pain, pathophysiology, (3) muscle, pain, microdialysis, (4) mus-cle, pain, induced. The searches were limited to papers in English and resulted in 89articles after duplicates were removed. Firstly, the abstracts of these articles wereread, and when abstracts were found to be relevant for this review the full paperswere scrutinized.

Muscle biopsy studies

The muscle biopsy technique provides a snap-shot approach. The biopsy includesmuscle fibres, connective tissue and extracellular space, and is useful for detectionof possible structural alterations in painful conditions. Nine studies addressing trape-zius muscle fibre abnormalities have been published. Eight of them have previouslybeen reviewed.6,35 Standard histological methods were made with some variations.Major findings in myalgic and non-myalgic subjects exposed to demanding neck andarm work tasks were increased fibre cross-sectional areas and reduced capillarizationper fibre area, the latter only in women, possibly indicating disturbances of oxidative

metabolism.

36

Furthermore, various mitochondrial disturbances of type I fibres,named moth-eaten fibres and ragged red fibres, were found to be more frequent insubjects with pain.35

The microdialysis technique

Microdialysis is a technique for studying the local biochemistry of individual tissues inthe body.37 The technique has been extensively used in neuroscience to monitor neu-rotransmitter release, but has also found application in monitoring the biochemistry ofperipheral tissues in both animals and humans.37 The basic principle is to mimic the

function of a capillary blood vessel by perfusing a thin dialysis tube implanted intothe tissue with a physiological saline solution. Substances can pass, by simple diffusion,across the dialysis membrane along the concentration gradient. The dialysate is ana-lysed chemically and reflects the composition of the extracellular fluid. Microdialysis


7/28/2019 {999B206B-BA2D-4F85-B869-6DE0133D9FCB}18

7/17

thus allows for continuous sampling of compounds in the muscle interstitial space,where nociceptor free nerve endings terminate, and in close proximity to the musclefibres, providing accurate information on regional biochemical changes before suchcompounds are diluted and cleared by the circulatory system.

Biochemical studies of non-myalgic and myalgic muscles in human subjects

Metabolites

In a study on six healthy men, Rosendal et al found marked changes in muscle inter-stitial lactate, pyruvate and potassium in response to repetitive low-force contractionsof the trapezius muscle, which were not reflected in plasma.38 The findings were in-terpreted to be due to inhomogeneous activation rather than insufficient bloodflow. Likewise, a fast and marked increase in interleukin 6 (IL-6) was found during ex-ercise.39 It was speculated that the high IL-6 level could be partly attributable to localchanges in metabolic demands during exercise39, but this could not be confirmed ina study of women with and without long-standing trapezius myalgia.40,41 Althoughthe myalgic women were found to have increased levels of pyruvate and lactate atrest and during exercise, indicating hyper-metabolism, uniform levels of local bloodflow were found in the groups during rest and exercise.41 In support of these findings,in another study on 20 healthy women who performed either 30 or 60 minutes of re-petitive low-force arm work, Flodgren et al found that interstitial trapezius muscle glu-tamate and lactate increased significantly in response to repetitive low-force work.42

However, no further increase with increasing work duration was found. Neither werealterations in prostaglandin E2 (PGE2) or local muscle oxygenation, assessed by near-infrared spectroscopy, affected by the duration of work.42

Recently, McIver et al found that eight women with chronic widespread myalgia andhyperalgesia i.e. fibromyalgia (FM) patients responded during exercise to nitricoxide with higher muscle interstitial lactate levels compared to controls; nitric oxideis known to have many physiological actions, including vasodilatation.43

Pain-related substances

In a myalgic group of women, the algesic substances serotonin and glutamate wereincreased and correlated to pain intensity and decreased pain pressure thresholdsrespectively.41 Glutamate is a well-known pain modulator in the human central

nervous system, acting via the N-methyl-D-aspartate (NMDA) receptor.44 Directand indirect evidence in animals has shown that excitatory amino acid receptors i.e. glutamate receptors are present on the peripheral ends of small-diameter pri-mary afferents in several tissues such as muscle.45 The role of glutamate in peripheralnociception in humans is unclear. Tension-type headache is not associated with in-creased peripheral glutamate46, whereas increased glutamate levels and NMDA recep-tors have been demonstrated in painful tendon tissue.47 Several studies havedemonstrated that injections of glutamate increase pain intensity48,49, but it is difficultto compare these finding with Rosendals studies40,41 because higher doses are used inthe injection studies. Although high interstitial glutamate levels were demonstrated

in a study of myalgic and non-myalgic women, no differences in interstitial glutamateand PGE2 levels between the groups were found.

50 A possible difference betweensubjects of these studies may contribute to the inconsistent glutamate finding. Thepain history, the present pain, and clinical muscular neck status of the subjects are


7/28/2019 {999B206B-BA2D-4F85-B869-6DE0133D9FCB}18

8/17

sparsely presented in the Flodgren study.50 The myalgic subjects studied by Rosendalet al40,41 comprised subjects reporting considerable long-standing pain, distinct cur-rent muscular signs confirmed at clinical examination, and most were on disabilityleave. Shah et al51 examined the local biochemical milieu in the trapezius muscle ofhealthy subjects and subjects with neck pain before, during, and after stimulation ofthe hypersensitive nodule. Bradykinin, calcitonin gene-related peptide, substance P,

tumor necrosis factor a, interleukin 1b, serotonin and norepinephrine were foundto be significantly higher in the myalgic group and related to external stimulationrather than the hypersensitive nodule.51 Also Boix et al studied the potent algogen,and key mediator of inflammatory hyperalgesia, bradykinin.52 It was found that duringbilateral shoulder abduction sustained until exhaustion, healthy women liberated intra-muscular bradykinin which correlated positively with pain intensity.52 Ashina and co-workers have investigated local tenderness in trapezius muscle of patients with chronictension-type headache.53 The subjects performed static exercises (10% of maximalforce), and it was found that the exercise-related increase in blood flow was lowerin patients than in controls.53 This increase was interpreted as related to increased

sympathetic activity in the chronic painful state. No signs of altered metabolism or in-flammation were found in the tender trapezius muscle of patients with tension-typeheadache.54

In animal experiments, serotonin (5-HT) has been found to mediate pain and hyper-algesia.55,56 Single injections of a combination of bradykinin and 5-HT in concentra-tions similar to the findings of 5HT in resting painful muscle41 results in muscle painand hyperalgesia.57

The deep craniofacial tissues such as the masseter muscle represent common sitesfor acute and chronic pain, and masseter myalgia is often associated with pain in neckshoulder muscle.58 Intramuscular administration of 5-HT into the human masseter

muscle has been demonstrated to induce pain.58 A positive correlation betweenpain intensity during the last week, allodynia, and the level of interstitial 5-HT in themasseter muscle in patients with fibromyalgia (FM) and patients with localized myalgiacompared to controls has been reported.59 Furthermore, FM patients also seem tohave a higher fraction of 5-HT in the masseter muscle compared to the level in bloodserum.59

The effects of intramuscular glucocorticoid (GC) on the level of 5-HT and associ-ated changes in pain and tenderness ofthe masseter muscle in subjects with local mas-seter muscle pain has been examined.60,61 A negative correlation regarding 5-HT andpressure pain threshold and pressure pain tolerance was found after GC injections in

this study. PGE2 levels were also found to be related to muscular pain in FM patients62

,and intramuscular administration of GC in the masseter muscle of FM patients andsubjects with masseter myalgia resulted in a decrease in muscle PGE2 and a decreasein resting pain in FM patients.61 Thus masseter muscle pain was interpreted to bepartly due to peripheral inflammation in FM. Peripheral inflammation as a cause ofpain is disputed by other studies. Studies on painful conditions found no indicationof PGE2 being associated with trapezius myalgia

50 or tendon pain63, as well as findingsimilar levels of the pro-inflammatory cytokine IL-6 in myalgic and non-myalgicsubjects.40

Increased potassium levels have also been speculated to be related to muscle pain.

Graven-Nielsen et al have presented an in-vivo muscle model of muscle pain, and sug-gested that pain activation and cessation were related to increased intramuscularsodium and potassium respectively.64 However, Green et al did not find potassiumrelated to ischaemic myalgia in healthy subjects.65 Despite this, increased potassium


7/28/2019 {999B206B-BA2D-4F85-B869-6DE0133D9FCB}18

9/17

levels have been shown in response to repetitive work38 and in subjects with trapeziusmyalgia.40

CLINICAL DIAGNOSIS OF NECK AND SHOULDER MYALGIA

The basis for the diagnostic criteria of neck and shoulder myalgia is relatively vague,and the diagnostic terminology and methods for assessment of neck and upper-limbmusculoskeletal disorders are variable. This implies that several more or less specificand partly overlapping diagnoses exist in clinical practice and epidemiological re-search. A typical anamnesis with progressing neck and shoulder pain and no othersymptoms or signs does not require investigations such as radiography, magnetic res-onance imaging, electromyography or nerve conductance velocity testing. Thepatients complaints and the manual clinical examination are the most important in-struments in the process of diagnosis. A standardized clinical examination protocolleading up to diagnoses of the neck and upper extremity based on carefully defined

criteria (Table 1) was developed and has recently been modified.13,66

In short, thestandardized clinical examination included questions on pain, tiredness and stiffnesson the day of examination, as well as physical tests including range of motion andtightness of muscles, pain threshold and sensitivity, muscle strength, and palpationof tender points. The protocol has been widely used in epidemiological researchand may also be appropriate in clinical practise. Sluiter et al reviewed the literatureon upper-extremity musculoskeletal disorders and proposed criteria for signs andsymptoms for the most common work-related disorders.67 When criteria forassessing pain and non-articular soft-tissue disorders of neck and upper limb werereviewed, it was concluded that the diagnosis relies heavily on the clinical opinions

of the investigators.

68

Furthermore, data were found to be insufficient to indicatethat the criteria are repeatable, sensitive or specific; 27 classifications systems forupper-limb musculoskeletal disorders were reviewed, and only slight agreementwas found between the systems.69

PREVENTIVE INTERVENTIONS

The first recommendations given by the NRC report is that a broad comprehensiveeffort to promote ergonomic as well as other preventive strategies is highly justified.14

This is based on the consequences of musculoskeletal disorders for both the individual

and society, in combination with the evidence that these problems are at least to somedegree preventable. The broad consensus of the multifactorial element in the develop-ment of musculoskeletal neckshoulder disorders indicates the need for a combinedphysical, psychosocial and organizational approach to prevention.70 This view is sup-ported by a number of newer reviews that also stress the participatory element asimportant for successful intervention.71 However, only a few reviews of effect-evaluatedinterventions are available. In 2006 a Cochrane review was performed evaluating ran-domized controlled studies until year 2000 on the effect of physical activity comparedto organizational changes on disorders in the low back and neck regions.72 However,there were not found any randomised controlled trials focusing on the neck. Apart

from this Cochrane review, there are several more general but systematic reviewson preventive interventions. Silverstein and Clark reviewed 73 studies and concludedthat the largest body of evidence for the prevention of neckshoulder disorders stemsfrom multicomponent interventions, and that subject-oriented interventions are the


7/28/2019 {999B206B-BA2D-4F85-B869-6DE0133D9FCB}18

10/17

Table 1. Criteria for diagnosis of disorders of the neck and upper limbs. All findings were required.

Diagnosis Criteria

Tension neck syndrome Neck pain; sense of fatigue or stiffness in the neck; pain radiating

from the neck to the back of the head; tightness of muscles;

tender spots in the musclesCervical syndrome Pain radiating from the neck to the upper extremity; limited neck

movement; radiating pain provoked by test movements; decreased

sensibility in hands/fingers; muscle weakness of the upper limb

Cervialgiaa Neck pain, limited neck movement in at least four of six

directions. Diagnosis only if tension neck syndrome or

cervical syndrome is not present

Trapezius myalgiaa Neck pain, tightness of muscles, tender points in the muscles.

Diagnosis only if tension neck syndrome or cervical syndrome

is not present

Thoracic outlet syndrome Pain radiating to upper extremity, in the distribution of the ulnar

nerve; paresthesia in the distribution of the ulnar nerve;

positive Roos test (increase of the subjective symptom, not only

fatigue); intense tenderness over the brachial plexus. Diagnosis

only if tension neck syndrome or cervical syndrome is not present

Frozen shoulder Shoulder pain; progressive stiffness of the shoulder during the

last 3e4 months; limited outward rotation, and abduction

Supraspinatus tendinitis (n18) Shoulder pain: local tenderness over the tendon insertion; pain at

resisted isometric abduction

Infraspinatus tendinitis Shoulder pain; local tenderness over the tendon insertion; pain at

resisted isometric outward rotation

Bicipital tendinitis Shoulder pain; local tenderness over the tendon(s); pain at

resisted isometric elevation of the arm (straight and elevated 90)

and/or resisted isometric flexion of the elbow (flexed 90 hand

supinated)

Acromioclavicular syndrome Shoulder (epaulet pain); palpable tenderness of the joint; pain

provoked by horizontal adduction and/or by outward rotation

of the arm (90 abducted, with flexed elbow)

Lateral and medial epicondylitis Elbow pain; palpable tenderness of the lateral and/or medial

epicondyle; pain at resisted isometric extension or flexion of the

wrist; for the diagnosis lateral epicondylitis, pain and/or weakness

in gripping

De Quervains tendinitisa Pain at the wrist; tenderness at palpation of tendons the

thumb side of the wrist. Localized swelling, redness and heat

Overused hand syndromea Wrist pain; palpable tenderness of the wrist capsule of the

thenar- and hypothenar muscles and of the intrinsic muscles

of the hand

Peritendinitis/tenosynovitis Wrist pain; palpable tenderness of the tendon(s); local swelling;

redness, or heat

Carpal tunnel syndrome Nocturnal numbness of the hand; paraesthesia in the distribution

of the median nerve; positive Tinels sign over the carpal tunnel;

positive Phalens test; decreased sensibility in the distribution of

the median nerve: decreased strength in opposition of the thumb

Pronator syndrome Pain of the medial/proximal part of the forearm; local tenderness

over the edge of m. pronator teres; pain and decreased strength

in pronation; decreased flexion strength in pronation; decreased

flexion strength of the wrist and/or of the distal phalanxes

of the fingers IeII


7/28/2019 {999B206B-BA2D-4F85-B869-6DE0133D9FCB}18

11/17

least efficient.73 Lotters and Burdof reviewed 40 studies and concluded that althoughmany different interventions all showed some effect, the greatest effect resulted fromprimary prevention in the physically heavy jobs.74 Buckle and Devereux evaluated thereduction in biomechanical risk factors by organizational changes and work-place ad-

justments, and found that exposure could be reduced which could potentially reduceneckshoulder disorder.75 Likewise Leonard focused on education, and concluded thatthis could also potentially reduce risk factors by changing the behaviour of em-ployees.76 Brewer et al included 31 studies in a review on interventions in officework. Overall it was concluded that, due to the limited number of studies, therewas only moderate evidence for an effect by any form of intervention in officework.77 However, there probably could be a positive effect of interchanging the inputdevice in computer work77, and here it should be remembered that absence of evi-dence is not the same as evidence of absence.

Two reviews have looked at physical activity. Hildebrandt et al focused on 39 studies

on leisure-time activity, and Proper et al included 26 studies on work-placeactivities.78,79 Physical activity in leisure time was not associated with neckshoulderdisorders, but sedentary workers with low levels of leisure-time activity had a higherprevalence of neck disorders. Proper et al found strong evidence for a positive effectof physical activity at work on neckshoulder disorders.79 However, the evidence fora similar positive effect on sickness absence was rather limited due to a lack of high-quality studies. Since these reviews were published, a number of intervention studieshave focused on systematic strength training as an intervention among women withchronic disorders. While less intensive training, stretching, and aerobic training gener-ally showed no effect, a follow-up design could even document a long-term effect of

strength training.8082

In one study light resistance training has also been found to de-crease the intensity of neck pain among office workers83, while Brox and Frysteinfound no evidence for decrease in sickness absence with low-intensity physical activityinterventions.84

Table 1 (continued)

Diagnosis Criteria

Radial tunnel syndrome Pain in the elbow during rest; tenderness about 2e3 inches

distally of the lateral epicondyle; pain of the proximal, lateral

part of the forearm and pain and decreased strength in supination;

decreased strength in ulnar deviation

Ulnar nerve entrapment

at the elbow

Pain and paresthesia of numbness in the distribution of the

ulnar nerve; decreased sensibility of the fingers IVeV and of the

ulnar part of the back of the hand; positive Tinels sign over

the cubital tunnel; decreased strength in spreading the fingers and

in flexion of the distal phalanx of finger V

Ulnar nerve entrapment

the wrist

Pain and paresthesia or numbness in the distribution of the

ulnar nerve: decreased sensibility of the fingers IVeV; positive

Tinels sign over Guyons tunnel (volar/ulnar at the wrist);

decreased strength in spreading the fingers

Modified from Ohlsson et al (Ergonomics 1994; 37: 891897) with permission from Kerstina Ohlsson.a Diagnosis added by personal communication with Kerstina Ohlsson since the table was originally

published by Ohlsson et al (1994),66 and these have been added in 2006.13


7/28/2019 {999B206B-BA2D-4F85-B869-6DE0133D9FCB}18

12/17

SUMMARY

This review has focused on the physiology of neckshoulder pain and trapezius myalgia,its possible relationship to work, risk factors for its development, the latest knowledgeon changes in structure and biochemical milieu in painful muscles, and the most-usedstandards for diagnosing neckshoulder disorders as well as the state of the art inrehabilitation.

The review confirms earlier findings of evidence for a causal relationship betweenneck and shoulder disorders and highly repetitive work, forceful exertions, high level

of static contractions, prolonged static loads, and extreme postures, as well as com-binations of these factors.

Whether local muscular processes can explain chronic neckshoulder pain is oftenquestioned, and this has turned the focus towards central processing as the primary

Practice points

musculoskeletal disorder in the neckshoulder is one of the most frequentdisorders in the working population, and is more frequent among womenthan men

recent reviews confirm the strong evidence for an association between neckshoulder disorders and gender, repetitive movements, high force, work pos-tures, and combinations of these factors

there is some evidence for psychosocial factors being involved, particularly forhigh quantitative and mental demands

duration of computer use is evident as a risk factor for self-reported disorders there are several studies that report altered metabolism and increased intra-

muscular levels of algesic substances in subjects with long-standing neck andshoulder myalgia

a single, universal, simple classification system would probably advance the

management of these disorders, but at present no such classification systemexists

the patients complaints and manual clinical examination are at present themost important instruments in the process of diagnosis

strength training at the workplace seems to be a promising intervention to de-crease neck pain, while more controversy exists regarding less intensive phys-ical activity

Research agenda

to augment the knowledge of pathomechanisms in chronic myalgia, future re-search should preferably address intramuscular algesics with receptors alreadyidentified in skeletal muscle, and include experimental models to study algesicsubstances as well as relevant nociceptors

a single, universal, simple classification system is needed to advance the man-agement of these disorders


7/28/2019 {999B206B-BA2D-4F85-B869-6DE0133D9FCB}18

13/17

explanation for pain. However, new methodology and many recent publications haveindicated a role for local muscular processes as being causally related to pain. Severalstudies have reported altered metabolism and increased intramuscular levels of algesicsubstances in subjects with chronic neck and shoulder myalgia. Furthermore, there aresome indications of structural abnormalities in biopsies from painful muscles. Despitethis, criteria for neckshoulder disorders are not sufficiently repeatable, sensitive or

specific, and there is little agreement between the different classification systems.A single, universal, simple classification system would probably advance the manage-

ment of these disorders, but at present no such classification system exists. A steptowards reducing these disorders may be a consensus on the key elements of a classi-fication system.

Evidence for physical activity for rehabilitation of neckshoulder pain is slowlyemerging, and promising results are appearing on the effect of strength training. Still,because the pathophysiology of neckshoulder pain seems to be multifactorial, inter-ventional models including physical, psychosocial and organizational elements willprobably have the greatest effect on pain in the long run.

ACKNOWLEDGEMENTS

The authors would like to thank Professor Bjorn Gerdle, Division of RehabilitationMedicine, Linkoping, Sweden, and Professor Gisela Sjgaard, National Institute ofOccupational Health, Denmark, for their scientific input into this review based ontheir great insight into risk factors, pain physiology and rehabilitation medicine, andtheir contribution to many studies advancing the knowledge in this field. ResearcherAnne Katrine Blangsted is also thanked for her skilled assistance in searching for

and condensing the literature on risk factors. This review was supported by the SwedishResearch Council (K2005-27X-15316-01A) and the Swedish Council for Working lifeand Social research (2004-0289).

CONFLICT OF INTEREST STATEMENT

There are no conflicts of interest. No financial or personal relationship has inappro-priately influenced this work.

Appendix 1. Literature search on risk factors for work-relatedneckshoulder pain

As described under Literature search, 20002006, a systematic search for thenewest epidemiological literature on risk factors for neckshoulder was performed.The search was performed in OSHROM, MEDLINE, EMBASE and Cochrane(CDSR) as combinations of the four sets of keywords listed below. The resultswere restricted to review papers published from 2000 to 2006 in the English language.

The search terminology was arranged as sets of search keywords:

1. shoulder, neck, arm, upper extremity, forearm, head, musculoskeletal, upper limb,cervical, muscle

2. pain, discomfort, illness, nociception, fatigue, tired, stress, injury, strain, unpleasant-ness, disorder, myalgia


7/28/2019 {999B206B-BA2D-4F85-B869-6DE0133D9FCB}18

14/17

3. work, workplace, job, occupational, work-related4. risk factors, static load, repetitiveness, force, monotonous, office work, computer,

industry, psycho social, psychosocial, psychosocial factors at work, emotional de-mands, bottling up emotions, job insecurity, job strain, job control, social support,management quality, reward, meaning, predictability, conflicts at work, perceivedstress, stress at work, high job demands, effort reward imbalance, social support,

social network, job demands, role conflicts, role clarity, burnout, job satisfaction,family-work.

REFERENCES

1. Punnett L & Wegman DH. Work-related musculoskeletal disorders: the epidemiologic evidence and the

debate. Journal of Electromyography and Kinesiology 2004; 14(1): 1323.

2. Baldwin ML. Reducing the costs of work-related musculoskeletal disorders: targeting strategies to

chronic disability cases. Journal of Electromyography and Kinesiology 2004; 14(1): 3341.

3. Armstrong T, Buckle P, Fine L et al. Can some upper extremity disorders be defined as work-related?

The Journal of Hand Surgery 1996; 21(4): 727729.

4. Forde MS, Punnett L & Wegman DH. Pathomechanisms of work-related musculoskeletal disorders:

conceptual issues. Ergonomics 2002; 45(9): 619630.

*5. Sjgaard G & SgaardK. Muscle injury in repetitive motion disorders. Clinical Orthopaedics1998; 351: 2131.

*6. Visser B & van Dieen JH. Pathophysiology of upper extremity muscle disorders. Journal of Electromyog-

raphy and Kinesiology 2006; 16(1): 116.

7. Mitchell RI & Carmen GM. The functional restoration approach to the treatment of chronic pain in

patients with soft tissue and back injuries. Spine 1994; 19(6): 633642.

8. Sjgaard G, Sgaard K, Hermens HJ et al. Neuromuscular assessment in elderly workers with and

without work related shoulder/neck trouble: the NEW-study design and physiological findings. Euro-

pean Journal of Applied Physiology 2006; 96: 110121.

9. Schulte E, Kallenberg LAC, Christensen H et al. Comparison of the electromyographic activity in the

upper trapezius and biceps brachii muscle in subjects with muscular disorders: a pilot study. European

Journal of Applied Physiology2006; 96: 185193.

10. Hakala P, Rimpela A, Salminen JJ et al. Back, neck and shoulder pain in Finnish adolescents: National

cross sectional surveys. British Medical Journal 2006; 325: 743746.

11. Cote P, Cassidy JP, Carroll LJ & Kristman V. The annual incidence and course of neck, and shoulder pain

in the general population: a population based cohort study. Pain 2004; 112: 267273.

12. Jensen C. Development of neck and hand-wrist symptoms in relation to duration of computer use at

work. Scandinavian Journal of Work, Environment and Health 2003; 29(3): 197205.

*13. Juul-Kristensen B, Kadefors R, Hansen K et al. Clinical signs and physical function in neck and upper

extremities among elderly female computer users: the NEW-study. European Journal of Applied Physiology

2006; 96: 136145.

*14. National Research Council and the Institute of medicine. Musculoskeletal Disorders and the Workplace.

Washington, D.C.: National Academy Press, 2001.

15. Punnett L & Herbert R. Work-related musculoskeletal disorders: is there a gender differential, and if so,

what does it mean? Women and Health 2000; 38(6): 474492.

16. Walker-Bone K, Palmer KT, Reading I & Cooper C. Soft-tissue rheumatic disorders of the neck and

upper limb: prevalence and risk factors. Seminars in Arthritis and Rheumatism 2003; 33(3): 185203.

17. Treaster DE & Burr D. Gender differences in prevalence of upper extremity musculoskeletal disorders.

Ergonomics 2004; 47(5): 495526.

18. Malchaire J, Cock N & Vergracht S. Review of the factors associated with musculoskeletal problems in

epidemiological studies. International Archives of Occupational and Environmental Health 2001; 74(2): 7990.

19. van der Windt DA, Thomas E, Pope DP et al. Occupational risk factors for shoulder pain: a systematic

review. Occupational and Environmental Medicine 2000; 57(7): 433442.

20. Ariens GA, van Mechelen W, Bongers PM et al. Physical risk factors for neck pain. Scandinavian Journal of

Work, Environment and Health 2000; 26(1): 719.


7/28/2019 {999B206B-BA2D-4F85-B869-6DE0133D9FCB}18

15/17

21. Mork PJ & Westgaard R. Low-amplitude trapezius activity in work and leisure and the relation to shoul-

der and neck pain. Journal of Applied Physiology 2006; 100: 11421149.

22. Olsen HB, Christensen H & Sgaard K. An analysis of motor unit firing pattern during sustained low

force contraction in fatigued muscle. Acta Physiologica et Pharmacologica Bulgarica 2001; 26(1/2): 7378.

23. Sgaard K, Sjgaard G, Finsen L et al. Motor unit activity during stereotyped finger tasks and computer

mouse work. Journal of Electromyography and Kinesiology 2001; 11(3): 197206.

24. Birch L, Christensen H, Arendt-Nielsen L et al. The influence of experimental muscle pain on mo-tor unit activity during low level contraction. European Journal of Applied Physiology 2000; 83(23):

200206.

25. Forsman M, Birch L, Zhang Q & Kadefors R. Motor unit recruitment in the trapezius muscle with

special reference to coarse arm movements. Journal of Electromyography and Kinesiology 2001; 11:

207216.

26. Meijer EM, Sluiter JK & Frings D. What is known about temperature and complaints in the upper

extremity? A systematic review in the VDU work environment. International Archives of Occupational

and Environmental Health 2006; 79(6): 445452.

27. Gerr F, Marcus M & Monteilh C. Epidemiology of musculoskeletal disorders among computer users:

lesson learned from the role of posture and keyboard use. Journal of Electromyography and Kinesiology

2004; 14(1): 2531.

28. Juul-Kristensen B, Sgaard K, Stryer J & Jensen C. Computer usersrisk factors for developing shoulder,

elbow and back symptoms. Scandinavian Journal of Work, Environment and Health 2004; 30(5): 390398.

29. Veiersted KB, Nordberg T, Waersted M. A critical review of evidence for a causal relationship between

computer work and musculoskeletal disorders with physical findings of the neck and upper extremity.

Den Videnskabelige Komite Dansk Selskab for Arbejdsog Miljmedicin, editor. 153. 2006.

30. Ariens GA. Psychosocial risk factors for neck pain: a systematic review. American Journal of Industrial

Medicine 2001; 39(2): 180193.

31. Bongers PM, Kremer AM & Laak JT. Are psychosocial factors, risk factors for symptoms and signs of the

shoulder, elbow, or hand/wrist? a review of the epidemiological literature. American Journal of Industrial

Medicine 2002; 41(5): 315342.

32. Mense S. The pathogenesis of muscle pain. Current Pain and Headache Reports 2003; 7(6): 419429.

33. Mense S. Nociception from skeletal muscle in relation to clinical muscle pain. Review article. Pain 1993;

54: 241289.

34. Textbook of pain. 4th edn. London: Livingstone, 1999.

35. Hagg GM. Human muscle fibre abnormalities related to occupational load. European Journal of Applied

Physiology 2000; 83(23): 159165.

*36. Larsson B, Bjork J, Kadi F et al. Blood supply and oxidative metabolism in muscle biopsies of female

cleaners with and without myalgia. The Clinical Journal of Pain 2002; 20(6): 440446.

37. Ungerstedt U. Microdialysisprinciples and applications for studies in animals and man - review. Journal

of Internal Medicine 1991; 230(4): 365373.

*38. Rosendal L, Blangsted AK, Kristiansen J et al. Interstitial muscle lactate, pyruvate, and potassium dynam-

ics in the trapezius muscle during repetitive low-force contractions, measured with microdialysis. Acta

Physiologica Scandinavica 2004; 2004(182): 379388.

39. Rosendal L, Sgaard K, Kjr M et al. Increase in interstitial interleukin-6 of human skeletal muscle with

repetitive low-force exercise. Journal of Applied Physiology 2005; 98: 477481.

40. Rosendal L, Kristiansen J, Gerdle B et al. Increased levels of interstitial potassium but normal levels of

muscle IL-6 and LDH in patients with trapezius myalgia. Pain 2005; 119: 201209.

*41. Rosendal L, Larsson B, Kristiansen J et al. Increase in muscle nociceptive substances and anaerobic

metabolism in patients with trapezius myalgia: microdialysis in rest and during exercise. Pain 2004;

2004(112): 324334.

42. Flodgren GM, Hellstrom FB, Fahlstrom M & Crenshaw AG. Effects of 30 versus 60 min of low-load

work on intramuscular lactate, pyruvate, glutamate, prostaglandin E(2) and oxygenation in the trapezius

muscle of healthy females. European Journal of Applied Physiology 2006; 97(5): 557565.

43. McIver KL, Evans C, Kraus RM et al. NO-mediated alterations in skeletal muscle nutritive blood flow

and lactate metabolism in fibromyalgia. Pain 2006; 120(12): 161169.

44. Coggeshall RE & Carlton SM. Receptor localization in the mammalian dorsal horn and primary afferent

neurons. Brain Research. Brain Research Reviews 1997; 24(1): 2866.


7/28/2019 {999B206B-BA2D-4F85-B869-6DE0133D9FCB}18

16/17

45. Coggeshall RE & Carlton SM. Ultrastructural analysis of NMDA, AMPA, and kainate receptors on

unmyelinated and myelinated axons in the periphery. The Journal of Comparative Neurology 1998;

391(1): 7886.

46. Ashina M, Jorgensen M, Stallknecht B et al. No release of interstitial glutamate in experimental human

model of muscle pain. European Journal of Pain 2005; 9(3): 337343.

47. Alfredson H, Thorsen K & Lorentzon R. In situ microdialysis in tendon tissue: high levels of glutamate,

but not prostaglandin E2 in chronic Achilles tendon pain. Knee Surgery, Sports Traumatology, Arthroscopy1999; 7(6): 378381.

48. Cairns BE, Wang K, Hu JW et al. The effect of glutamate-evoked masseter muscle pain on the human

jaw-stretch reflex differs in men and women. Journal of Orofacial Pain 2003; 17(4): 317325.

49. Gazerani P, Wang K, Cairns BE et al. Effects of subcutaneous administration of glutamate on pain, sen-

sitization and vasomotor responses in healthy men and women. Pain 2006; 124(3): 338348.

50. Flodgren GM, Crenshaw AG, Alfredson H et al. Glutamate and prostaglandin E2 in the trapezius muscle

of female subjects with chronic muscle pain and controls determined by microdialysis. European Journal

of Pain 2005; 9(5): 511515.

51. Shah JP, Phillips TM, Danoff JV & Gerber LH. An in vivo microanalytical technique for measuring the

local biochemical milieu of human skeletal muscle. Journal of Applied Physiology 2005; 99(5): 1977

1984.

*52. Boix F, Roe C, Rosenborg L & Knardahl S. Kinin peptides in human trapezius muscle during sustained

isometric contraction and their relation to pain. Journal of Applied Physiology 2005; 98(2): 534540.

53. Ashina M, Stallknecht B, Bendtsen L et al. In vivo evidence of altered skeletal muscle blood flow in

chronic tension-type headache. Brain 2002; 125(Pt 2): 320326.

54. Ashina M, Stallknecht B, Bendtsen L et al. Tender points are not sites of ongoing inflammation -in vivo

evidence in patients with chronic tension-type headache. Cephalalgia 2003; 23(2): 109116.

55. Giordano J & Rogers LV. Peripherally administered serotonin 5-HT3 receptor antagonists reduce in-

flammatory pain in rats. European Journal of Pharmacology 1989; 170(12): 8386.

56. Taiwo YO & Levine JD. Serotonin is a directly-acting hyperalgesic agent in the rat. Neuroscience 1992;

48(2): 485490.

57. Babenko VV, Graven-Nielsen T, Svensson P et al. Experimental human muscle pain induced by intramus-

cular injections of bradykinin, serotonin, and substance P. European Journal of Pain 1999; 3(2): 93102.

58. Ernberg M, Hedenberg-Magnusson B, Kurita H & Kopp S. Effects of local serotonin administration

on pain and microcirculation in the human masseter muscle. Journal of Orofacial Pain 2006; 20(3):

241248.

59. Ernberg M, Hedenberg-Magnusson B, Alstergren P & Kopp S. The level of serotonin in the superficial

masseter muscle in relation to local pain and allodynia. Life Sciences 1999; 65(3): 313325.

60. Ernberg M, Hedenberg-Magnusson B, Alstergren P & Kopp S. Effect of local glucocorticoid injection on mas-

seter muscle level of serotonin in patients with chronic myalgia. Acta Odontologica Scandinavica 1998; 56(3):

129134.

61. Hedenberg-Magnusson B, Ernberg M, Alstergren P & Kopp S. Effect on prostaglandin E2 and leukotri-

ene B4 levels by local administration of glucocorticoid in human masseter muscle myalgia. Acta Odon-

tologica Scandinavica 2002; 60(1): 2936.

62. Hedenberg-Magnusson B, Ernberg M, Alstergren P & Kopp S. Pain mediation by prostaglandin E2 and

leukotriene B4 in the human masseter muscle. Acta Odontologica Scandinavica 2001; 59(6): 348355.

63. Alfredson H. The chronic painful Achilles and patellar tendon: research on basic biology and treatment.

Scandinavian Journal of Medicine and Science in Sports 2005; 15(4): 252259.

64. Graven-Nielsen T, McArdle A, Arendt-Nielsen L et al. In vivo model of muscle pain: Quantification of

intramuscular chemical, electrical and pressure changes associated with saline induced muscle pain in

humans. Pain 1997; 69: 137143.

65. Green S, Langberg H, Skovgaard D et al. Interstitial and arterial-venous [K] in human calf muscle during

exercise: effect of ischaemia and relation to muscle pain.Journal of Physiology2000; 15(529): 849861. Pt 3.

*66. Ohlsson K, Attewell RG, Johnsson B et al. An assessment of neck and upper extremity disorders by

questionnaire and clinical examination. Ergonomics 1994; 37(5): 891897.

67. Sluiter JK, Rest KM & Frings-Dresen MHW. Criteria document for evaluating the work-relatedness of

upper extremity musculoskeletal disorders. Scandinavian Journal of Work, Environment and Health 2001;

27(suppl 1): 1102. Finland, Vammalan Kirjapaino Oy.


7/28/2019 {999B206B-BA2D-4F85-B869-6DE0133D9FCB}18

17/17

68. Walker-Bone KE, Palmer KT, Reading I & Cooper C. Criteria for assessing pain and nonarticular soft-

tissue rheumatic disorders of the neck and upper limb. Seminars in Arthritis and Rheumatism 2003; 33(3):

168184.

69. Van Eerd D, Beaton D, Cole D et al. Classification systems for upper-limb musculoskeletal disorders in

workers: a review of the literature. Journal of Clinical Epidemiology 2003; 56: 925936.

70. Bernard B. Musculoskeletal disorders and workplace factors: a critical review of epidemiologic evidence for

work-related musculoskeletal disorders of the neck, upper extremity, and low back . 2 edn. Cincinnati, USA:U.S. Department of Health and Human Services, NIOSH, 1997.

71. Huang GD, Feuerstein M & Sauter SL. Occupational stress and work-related upper extremity disorders:

concepts and models. American Journal of Industrial Medicine 2002; 41(5): 298314.

72. Verhagen AP, Karels C, Bierma-Zeinstra SMA et al. Ergonomic and physiotherapeutic interventions for

treating work-related complaints of the arm, neck or shoulder in adults. Cochrane Database of Systematic

Reviews 2006; (3): CD003471. doi:10.1002/14651858.CD003471.pub3.

*73. Silverstein B & Clark R. Interventions to reduce work-related musculoskeletal disorders. Journal of Elec-

tromyography and Kinesiology 2004; 14(1): 135152.

74. Lotters F & Burdof A. Are changes in mechanical exposure and musculoskeletal health good perfor-

mance indicators for primary interventions? International Archives of Occupational and Environmental

Health 2002; 75(8): 549561.

75. Buckle PW & Devereux JJ. The nature of work-related neck and upper limb musculoskeletal disorders.

Applied Ergonomics 2002; 33(3): 207217.

76. Leonard D. The effectiveness of intervention strategies used to educate clients about prevention of

upper extremity cumulative trauma disorders. Work 2000; 14(2): 151157.

77. Brewer S, Eerd DV, Amick III IB et al. Workplace interventions to prevent musculoskeletal and visual

symptoms and disorders among computer users: a systematic review. Journal of Occupational Rehabilita-

tion 2006; 16(3): 317350.

78. Hildebrandt VH, Bongers PM, Dul J et al. The relationship between leisure time, physical activities and

musculoskeletal symptoms and disability in worker populations. International Archives of Occupational and

Environmental Health 2000; 73(8): 507518.

79. Proper KI, Koning M, Van der Beek AJ et al. The effectiveness of worksite physical activity programs on

physical activity, physical fitness, and health. Clinical Journal of Sport Medicine 2003; 13(2): 106117.

80. Ylinen J, Takala EP, Nykanen M et al. Active neck muscle training in the treatment of chronic neck pain in

women: a randomized controlled trial. The Journal of American Medical Association 2003; 289(19): 25092516.

81. Ylinen J, Takala EP, Kautiainen H et al. Effect of long-term neck muscle training on pressure pain thresh-

old: a randomized controlled trial. European Journal of Pain 2005; 9(6): 673681.

82. Ylinen JJ, Takala EP, Nykanen MJ et al. Effects of twelve-month strength training subsequent to twelve

month stretching exercise in treatment of chronic neck pain. Journal of Strength and Conditioning Research

2006; 20(2): 304308.

83. Sjogren T, Nissinen KJ, Jarvenpaa SK et al. Effects of a workplace physical exercise intervention on the

intensity of headache and neck and shoulder symptoms and upper extremity muscular strength of office

workers: a cluster randomized controlled cross-over trial. Pain 2005; 116(12): 119128.

84. Brox JI & Frystein O. Health-related quality of life and sickness absence in community nursing home

employees: randomized controlled trial of physical exercise. Occupational Medicine 2005; 55: 558563.


{999B206B-BA2D-4F85-B869-6DE0133D9FCB}18

Documents

Transcript of {999B206B-BA2D-4F85-B869-6DE0133D9FCB}18