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Work 42 (2012) 173–184 173DOI 10.3233/WOR-2012-1342IOS Press

Review Article

Musculoskeletal disorders in sign language

interpreters: A systematic review and

conceptual model of musculoskeletal disorder

development

Steven L. Fischera, Matthew M. Marshallb and Kathryn Woodcockc,∗aSchool of Kinesiology and Health Studies, Queen’s University, Kingston, ON, Canadab Department of Industrial and Systems Engineering, Rochester Institute of Technology, Rochester, NY, USAcSchool of Occupational and Public Health, Ryerson University, Toronto, ON, Canada

Received 1 April 2010

Accepted 3 June 2010

Abstract. Objective: Increasing evidence suggests that one in four sign language interpreters (SLIs) may experience symptoms of

musculoskeletal disorders (MSDs) severe enough to modify their activities. This systematic review examined published research

on SLIs and the development of MSD pathology, seeking to identify injury pathways to MSDs and work-related factors with thelargest impact in targeted MSD-reduction intervention.

Methods: Embase and Medline electronic databases were searched from their inception until March 2009, finding 23 eligible

peer-reviewed papers related to MSD pathology in SLIs, including narrative reviews, intervention studies, and qualitative and

quantitative research.

Results: Three factors were shown to have limited support as increasing the risk for MSD pathology in SLI: increased mechanical

exposure, stress, and speaker’s pace (a contributor to movement rate). Overall, the published literature was rated medium to low

quality, with limited statistical methods and power, often lacking description of how dependent variables were measured, and

how risk of biasing or confounding was minimized.

Conclusions: A conceptual model was developed to integrate the multi-factorial elements of MSD pathology development among

SLIs. However, to strengthen development of evidence-based practice and policy-driven initiatives, higher-quality research is

warranted to examine MSD pathology amongst SLIs.

Keywords: Physical risk factors, cognitive risk factors, evidence-synthesis

1. Introduction

Sign language interpreters (SLIs) facilitate commu-nication between hearing and deaf people through si-multaneous translation of spoken language into signed

∗Address for correspondence: Kathryn Woodcock, School of Occupational and Public Health, Ryerson University, 350 VictoriaStreet, Toronto, Ontario, M5B 2K3 Canada. Fax: +1 416 979 5377;E-mail: kathryn.woodcock@ ryerson.ca.

language, or vice versa. Like any simultaneous transla-tion or interpretation, it entails a high cognitive demand

to semantically understand a message and communi-cate it using the alternate language. However, unlikemost interpretation, the nature of signed languages alsoentails high physical demand as an interpreter producesphysical signs to communicate through a visual, ratherthan an audible medium. The idea that these physicaldemands in concert with highcognitive demands placesSLIs at an elevated risk for developing musculoskeletal

1051-9815/12/$27.50 2012 – IOS Press and the authors. All rights reserved



174 S.L. Fischer et al. / Musculoskeletal disorders in sign language interpreters

disorders was proposed over 20 years ago [1,2].

Sign language interpretation is a young profession.As the profession grows, organizing bodies such as theAssociation for Visual Language Interpreters of Cana-da (AVLIC) and the Registry of Interpreters for theDeaf (RID) in the United States have formed. Theirrole is to act on behalf of SLIs, developing effectivepolicies and programs to support the continued growthof their profession. The occurrence of musculoskele-tal disorders (MSDs) currently presents a problem forthese organizations as it limits the ability to develop ahealthy, capable population of SLIs. To deal with thischallenge more evidence and guidance is necessary tofeed into appropriate policies and practices to help mit-

igate MSD risks for SLIs. Recognizing the potentialimpact of MSDs on the growth of the profession, theNational Institute for Occupational Safety and Health(NIOSH) was asked to evaluate the scope of MSDsamongst SLIs. Their assessment found that 92% of respondents reported symptoms during the year priorto the study, and that more than 30% of clinically eval-uated practitioners met a symptom case definition [3].

Several other research studies have evaluated, as-sessed, quantified, and intervened to both examine andreduce the incidence and severity of MSDs in SLIs.This body of research highlights a number of factorsfor consideration when addressing MSDs in the sign

language profession. As AVLIC and RID move for-ward developing effective MSD reduction and preven-tion policies, it is important to synthesize and evalu-ate the existing body of knowledge to provide a strongfoundation of evidence for developing these directives.Synthesizing this knowledge will help provide a morecomprehensive understanding of how various work fac-tors may influence MSD development. Further, thissynthesis will aid in developing evidence-based pre-vention and reduction strategies to alleviate the influ-ence of the work factors identified as impacting MSDdevelopment.

The purpose of this paper was to systematically re-

view the peer-reviewed literature regarding MSDs andSLIs to reveal critical factors associated with MSDs,and to provide a framework for further research by us-ing the information gathered fromthe review to developa conceptual model incorporating both cognitive andphysical demands into the etiology of MSDs in SLIs.

2. Methodology

2.1. Search strategy

An initial search was conducted to find all peer-reviewed research related to the profession of sign lan-

guage interpreting. Two electronic databases, Embase

and Medline, were searched from their inception untilMarch 2009. The broad search term “sign language”

was selected as an inclusive approach to obtaining all

the research related to the field, given that it is a rel-

atively young profession. Only peer-reviewed articles

were considered. Conference proceedings were ex-

cluded as it was often not possible to determine if they

had been peer-reviewed, and typically lacked suf ficient

information to adequately assess quality. Titles and

abstracts were screened to determine if the research

made reference to injury prevalence, MSD hazard ex-

posures, MSD interventions, or the general work per-

formed during sign language interpreting. No further

inclusion criteria were required, as there was a paucity

of research available, and any further inclusion criteria

would have greatly reduced the research available for

further assessment. Further, the reference lists of the

accepted articles were also searched to determine if any

additional articles could be found.

2.2. Quality appraisal

Research studies meeting our inclusion criteria in-

corporated reviews, intervention studies, qualitative

research and quantitative research studies. A specif-

ic quality appraisal checklist was developed for ea-ch, modified from those created and made available

through the Scottish Intercollegiate Guidelines Net-

work (Edinburgh, Scotland, http://www.sign.ac.uk).

A scoring method was developed for each modified

checklist to allow an overall quantitative score to be

tabulated for each paper, based on the reviewers’ sub-

jective responses to each checklist question.

The overall scores were used to assess the method-

ological quality and impact of each individual paper. A

three-point rating scale (low, medium or high quality)

was then used to grade each research paper (adapted

from [4]) based on the overall score. The grades were

assigned by dividing the actual score by the maximum

score possible, resulting in a percentage grade similar

to an academic grade. The cut-points for each grading

bin were as follows: < 50% = “low” quality study;

50% < 85% = “medium” quality study; 85% =

“high” quality study.

Each study was reviewed by two independent re-

viewers (SF, MM). Each reviewer selected the check-

list he/she felt was most appropriate, and completedthe

appraisal. Upon completion of the reviews, reviewer’s

appraisals were compared first, to determine if they se-

lected the same checklist for each paper, and second to



S.L. Fischer et al. / Musculoskeletal disorders in sign language interpreters 175

Table 1Guideline for establishing the level of evidence. The level of evidence for each factor

associated with MSD pathology in SLIs was determined using the guidelines describedthe table

determine if their scoring resulted in the same grade be-

ing assigned. If they did not choose the same appraisal

checklist, or the final grade differed, a third reviewer

(KW) independently reviewed those papers. Only re-

viewers SF and KW reviewed the paper co-authored byMM to limit any conflict of interest.

2.3. Data extraction and evidence synthesis

Following individual appraisal and scoring of each

paper, data were extracted from each report to generate

an evidence synthesis. Specific information extracted

from each study included information on the number of

interpreters studied, dependent variables, independent

variables, controlled variables, uncontrolled variables,

specific comparisons made in the study, follow-up pe-

riod, effect size, funding sources and general studyconclusion. The specific factors influencing MSDs in

SLIs were then combined across studies using an evi-

dence synthesis approach adapted from that described

by Slavin [5]. Using this approach, evidence is pooled

and ranked according to the number of studies shar-

ing the result and the quality of those studies. For

example, if three studies all scoring as ‘high’ in the

quality appraisal each demonstrated the same relation-

ship between a workplace factor and MSD in SLIs, this

would be considered a ‘strong’ levelof evidenceand we

should immediately intervene on this factor to reduce

MSD risks. Table 1 describesthe five levels of evidence

possible and the corresponding quality and quantity of

papers needed to support that level of evidence.

3. Results

3.1. Literature search and selection for relevance

We identified 1355 articles using the search term

“signlanguage”.Afterdifferent databaseswere merged,

duplicate articles removed, abstracts reviewed, and ref-

erences searched we included 23 articles for quality

appraisal (Fig. 1).

Of the 23 papers selected for quality appraisal, re-

viewers SF and MM agreed both in checklist selection

and in grade for 20 papers. Disagreements were me-

diated by use of KW rating for two quasi-review pa-pers [6,7] where the original reviewers disagreed on the

appropriate checklists and in one instance [8] where the

reviewers disagreed on the grade.

3.2. Quality appraisal

Research articles were categorized into one of four

research methods: Reviews, intervention studies, qual-

itative research and quantitative research. Of the 23

studies reviewed, none were considered of high qual-

ity (> 85%). Five studies were considered of medi-

um quality (50–85%). The remaining eighteen stud-




Fig. 1. A schematic description of the search strategy and results. Following the decision process, 23 papers were included in the evidencesynthesis.

ies were considered low quality (< 50%). Many of

the studies scoring as low quality often lacked details

regarding how the dependent variables were measured

with respect to controlling for covariates and using re-

liable metrics for measuring or observing those vari-

ables. Further, these studies often did not report which,

if any, methods were employed for reducing the risk of

biasing or confounding. Statistical methods and statis-

tical power were also common concerns among those

studies scoring as low quality.

3.3. Data extraction

Due to the variety of research designs reviewed, it

was not possible to combine data or outcomes from dif-

ferent studies using a meta-analysis approach. Rather,

independent and dependent variables were extracted

along with a description of their impact on MSDs (Ta-

ble 2). Based on the extracted data, dependent vari-

ables influencing MSDs in SLIs were sorted into 13

different MSD impact categories to better enable the

evidence synthesis (Table 3). Table 4 presents the evi-

dence synthesis. Due to the lack of highquality studies,

a classification of ‘limited evidence’ was the highest

possible outcome for any given MSD impacting factor.

A classification of mixed evidence did not occur, as no

two studies reported contrasting results.

4. Discussion

The results of this review demonstrate that there is apaucity of strong evidence upon which to build MSD

prevention and reduction policies for sign language in-

terpreter organizations. However, the results of the re-

view indicate that both cognitive and physical factors

share limited evidence for having an impact on MSDs

in SLIs. Although the general quality of the research

was scored as low, it was noteworthy that the body of

research did not produce mixed results for any factor.

This may indicate that there are some clear relation-

ships between these factors and MSDs in SLIs, but not

enough high-quality research has been completed to

confirm the strength of these relationships.

Three factors emerged as having limited evidence

to support that they increase the risk of developing an

MSD in SLIs: increased mechanical exposure, high

speaker pace and stress. The mechanical exposure cat-

egory represents increased postural deviation and in-

creased sign velocity or acceleration. Both postural

deviation and increased motion have been linked to an

increased risk of MSD in the upper extremity [9–11].

Speaker pace on its own is not likely linked by any

studies directly to MSD development, but it was shown

to increase mechanical exposures, more specifically

repetitive motion [12,13]. Despite the relationship of




T a b l e 2

D a t a e x t r a c t i o n . I n f o

r m a t i o n r e l a t e d t o t h e i n d e p e n d e n t a n d d e p e n d

e n t m e a s u r e s w e r e e x t r a c t e d f r o m e a c h s t u d y a n d a r e p r e s e n t e d i n t h e t a b l e .

T h e i m p a c t o f M S D

d e s c r i b e s t h e n a t u r e o f t h e r e l a t i o n s h i p s e x a m i n e d . T h e g r a d e a s s i g n m e n t d e s c r i b e s t h e q u a l i t y l e v e l o f t h e r e s e a r c h s t u d y

b a s e d o n t h e e x p e r i m

e n t a l d e s i g n a n d s t u d y d e s c r i p t i o n . T h e s h a d i n g d i s t i n g u i s h e s s t u d y t y p e s b e g i n n i n g w i t h n a r r a t i v e r e v i e w ( s h a d e d g r e y ) ,

i n t e r v e n t i o n ( n o s h a d i n g ) , q u a l i t a t i v e r e s e a r c h ( s h a d e d g r e y ) , a n d q u a n t i t a t i v e r e s e a r c h ( n o s h a d i n g )

A u t h o r s

I n d e p e n d e n t v a r i a b l e

D e p e n d e n t v a

r i a b l e

I m p a c t o n M S D

D e a n &

P o l l a r d [ 7 ]

D

e g r e e o f f i t - H o w d o e s S L I f i t

w i t h i n t h e K a r a s e k d e m a n d - c o n t r o l

m o d e l

J o b D e m a n d ( l i n g u i s t i c ,

e n v i r o n m e n t a l , i n t e r p e r s o n a l ,

i n t r a p e r s o n a l )

J o b C o n t r o l

* O u t c o m e s s u

b j e c t i v e l y

d e t e r m i n e d b a s e d o n a n a r r a t i v e

r e v i e w

U s i n g a d e m a n d - c o n t r o l m

o d e l ,

S L I s a r e a t i n c r e a s e d r i s k d

u e t o

h i g h j o b d e m a n d s a n d l o w

j o b

c o n t r o l

L o w

S a n d e r s o n

[ 1 ]

N

o n e

N o n e

N a r r a t i v e r e v i e w a n d c o m m

e n t a r y

s u g g e s t s h i g h p r e v a l e n c e o

f

o v e r u s e s y n d r o m e s i n S L I s

L o w

S t e d t [ 6 ]

N

o n e

N o n e

N a r r a t i v e r e v i e w a n d c o m m

e n t a r y

s u g g e s t s h i g h p r e v a l e n c e o

f c a r p a l

t u n n e l s y n d r o m e i n S L I s

L o w

D e l i s l e e t a l .

[ 1 5 ]

S t r e s s m a n a g e m e n t i n t e r v e n t i o n

W

o r k s t y l e i n t e r v e n t i o n

P a i n p e r c e p

t i o n

P s y c h o l o g i c a l s t r e s s

M e c h a n i c a l e x p o s u r e ( E M G ,

e l e c t r o g o n i o m e t r y )

M i x e d r e s u l t s - B o t h i n t e r v

e n t i o n s

r e d u c e d o u t c o m e s ; h o w e v e r

r e d u c t i o n s w e r e p a r t i c i p a n t a n d

i n t e r v e n t i o n s p e c i f i c

M e d i u m

F e u e r s t e i n e t

a l . [ 1 4 ]

M

u l t i - c o m p o n e n t i n t e r v e n t i o n

( 1 1 w e e k e d u c a t i o n p r o g r a m )

# o f r e p o r t e

d c a s e s

C o m p e n s a t i o n c o s t s

T h e # o f c l a i m s a n d t o t a l

c o m p e n s a t i o n c o s t s w e r e r e d u c e d

f o r t h r e e y e a r s p o s t i n t e r v e

n t i o n

L o w

D e C a r o e t a l .

[ 2 2 ]

G

r o u p e d b y p a i n s c o r e s

# o f m i c r o r e s t b r e a k s

P a c e

P o s t u r a l d e v i a t i o n s

* v a r i a b l e s d e t e r m i n e d u s i n g

q u a l i t a t i v e a s s e s s m e n t

H i g h e r p a i n g r o u p h a s f e w e r

m i c r o r e s t b r e a k s , a f a s t e r p a c e

a n d m o r e p o s t u r a l d e v i a t i o

n

L o w

F e u e r s t e i n e t

a l . [ 2 4 ]

G

r o u p e d b y N I O S H c a s e

d e f i n i t i o n o f u p p e r e x t r e m i t y M S D

G e n d e r

Y e a r s w o r k e d

J o b p r e s s u r e

F e a r o f d e v e l o p i n g p a i n

W o r k i n g w i t h p a i n t o e n s u r e

q u a l i t y o f w o r k

W r i s t d e v i a

t i o n s f r o m n e u t r a l

F e m a l e s w e r e m o r e l i k e l y t o

b e c o m e i n j u r e d

I n c r e a s e s i n a l l o t h e r o u t c o

m e s

w e r e a s s o c i a t e d w i t h a n i n c r e a s e d

r i s k o f m e e t i n g t h e N I O S H

c a s e

d e f i n i t i o n f o r u p p e r e x t r e m

i t y

M S D

M e d i u m




T a b l e

2 , c o n t i n u e d

S m i t h e t a l .

[ 3 3 ]

G

e n d e r

P r e v a l e n c e

o f h a n d a n d w r i s t

p r o b l e m s

F e m a l e s w e r e m o r e l i k e l y t o

e x p e r i e n c e h a n d a n d w r i s t

p r o b l e m s

L o w

A u t h o r s

I n d e p e n d e n t v a r i a b l e

D e p e n d e n t v

a r i a b l e


J o h n s o n &

F e u e r s t e i n

[ 2 3 ]

O

p e n e n d e d r e s p o n s e t o

q u e s t i o n I n t h e s p a c e b e l o w , p l e a s e

t e l l u s w h a t y o u a r e d o i n g , i f

a n y t h i n g , t h a t y o u t h i n k i s

c o n t r i b u t i n g t o y o u r s y m p t o m s o r

p r e v

e n t i n g y o u f r o m e x p e r i e n c i n g

s y m

p t o m s

S L I s p e r c e p t i o n s o f M S D

i n d i c a t e d i n r e s p o n s e s

M o s t c o m m o n r e s p o n s e

( 1 5 . 5 5 %

o f r e s p o n d e n t s ) f e l t t h a t

l o n g

w o r k h o u r s a n d n o b r e a k

s w a s

m o s t r e l a t e d t o i n i t i a t i o n

o r

e x a c e r b a t i o n o f s y m p t o m

s

L o w

M a d d e n [ 2 6 ]

G

r o u p e d b y p r e v a l e n c e o f

o c c u p a t i o n a l o v e r u s e s y n d r o m e

Y e a r s w o r k e d

I n c r e a s e d y e a r s w o r k e d w a s

a s s o c i a t e d w i t h i n c r e a s e d

p r e v a l e n c e o f o c c u p a t i o n a l

o v e r u s e s y n d r o m e

L o w

M e a l s e t a l .

[ 2 9 ]

J

o b d e s c r i p t i o n

P r e v a l e n c e o f o v e r u s e

s y n d r o m e s i n

S L I s

U p p e r l i m b a b n o r m a l i t i e s

i d e n t i f i e d a n d a c c e n t u a t e d b y

i n t e r p r e t i n g i n c l a s s r o o m

o r p u b l i c

s p e a k i n g s e t t i n g s

L o w

S c h e u e r l e e t

a l [ 2 7 ]

G

r o u p e d b y p r e v a l e n c e o f p a i n /

d i s c

o m f o r t

H o u r s w o r k e d p e r w e e k

I n c r e a s e d h o u r s w o r k e d

p e r w e e k

w a s s i g n i f i c a n t l y c o r r e l a

t e d w i t h

r e p o r t e d p a i n / d i s c o m f o

r t

L o w

S t e d t [ 3 4 ]

S

u r v e y q u e s t i o n s r e l a t e d t o t h e

p r e v

a l e n c e o f p a i n a n d s y m p t o m s

i n d i c a t i v e o f r e p e t i t i v e s t r a i n i n j u r y

S u r v e y r e s p o n s e s

S u r v e y r e s p o n s e s i n d i c a t e t h a t 3 5

o f 4 0 r e s p o n d e n t s h a d t w

o o r

m o r e s y m p t o m s a s s o c i a t e d w i t h

r e p e t i t i v e s t r a i n i n j u r y

L o w

W a t s o n [ 2 ]

S

u r v e y q u e s t i o n s r e l a t e d t o t h e

p r e v

a l e n c e o f i n t e r p r e t e r b u r n - o u t

S u r v e y r e s

p o n s e s

R e s u l t s d i d n o t p e r m i t m

e a n i n g f u l

i n f o r m a t i o n t o b e e x t r a c t e d .

e n d e d

s u r v e y

q u e s t i o n s w i t h

m e t h o d t o g r o u p o r c

o m b i n e

r e s p o n s e s )

L o w

C o h n e t a l .

[ 2 5 ]

G

r o u p e d b y c l i n i c a l d i a g n o s i s

l e n g t h o f t i m e s i g n i n g

y e a r s o f e x

p e r i e n c e

s i g n s t y l e

T h o s e w i t h c l i n i c a l f i n d i n g s r e p o r t

f e e l i n g p a i n o n s e t f o l l o w

i n g

a p p r o x i m a t e l y 1 . 8 h o u r s

o f

i n t e r p r e t i n g

S y m p t o m a t i c i n t e r p r e t e r s w o r k e d

a n a v e r a g e o f 2 5 h o u r s p

e r w e e k

T h o s e o f t e n f i n g e r s p e l l i n g

p r e s e n t e d w i t h m o r e s m a l l j o i n t

i n v o l v e m e n t , w h i l e t h o s e s i g n i n g

h a d m o r e s h o u l d e r

g i r d l e

i n v o l v e m e n t

L o w

( O p e n

n o




T a b l e

2 , c o n t i n u e d

A u t h o r s

I n d

e p e n d e n t v a r i a b l e

D e p e n d e n t v

a r i a b l e


D e l i s l e e t a l .

[ 2 1 ]

P h y s i c a l e x p o s u r e

E l e c t r o m y o g r a p h y ( E M G )

( m u l t i p l e E M G r e l a t e d

o u t c o m e s )

E l e c t r o g o n

i o m e t r y ( k i n e m a t i c

o u t c o m e s )

K i n e m a t i c m a r k e r s ( j o i n t

a n g u l a r

v e l o c i t y a n d a c c e l e r a t i o n ) w e r e

a b o v e r e p o r t e d t h r e s h o l d

l e v e l s

s e p a r a t i n g h i g h a n d l o w r

i s k

g r o u p s

1 9 9 3 )

E M G g a p s a n a l y s i s r e v e a l e d

t h a t S L I s h a v e f e w e r m i c r o

b r e a k s

i n

t h e t r a p e z i u s m

u s c l e

t h a n

k e y b o a r d u s e r s

M e d i u m

F e u e r s t e i n &

F i t z g e r a l d

[ 2 0 ]

G r o u p e d b y p a i n s c o r e

# o f r e s t b r e a k s

w r i s t d e v i a t i o n s f r o m n e u t r a l

# o f w o r k e n v e l o p e

e x c u r s i o n s

p a c e o f f i n

g e r m o t i o n s

T h o s e r e p o r t i n g p a i n h a d

f e w e r #

o f r e s t b r e a k s , i n c r e a s e d # o f w o r k

e n v e l o p e e x c u r s i o n s , m o r e w r i s t

d e v i a t i o n s a n d a q u i c k e r p a c e

M e d i u m

H a g b e r g e t

a l . [ 1 2 ]

P a c e

E M G

I n c r e a s e d a m p l i t u d e o f E M G w i t h

i n c r e a s e d p a c e

L o w

P e p e r &

G i b n e y [ 3 0 ]

P s y c h o p h y s i c i o l o g i c a l

c o r r e l a t e s

R e s p i r a t i o n R a t e

P e r i p h e r a l

t e m p e r a t u r e

S k i n c o n d u c t a n c e

S u r f a c e E M

G

I n c r e a s e d r e s p i r a t i o n r a t e , h a n d

t e m p e r a t u r e , s k i n c o n d u c t a n c e ,

a n d u p p e r l i m b E M G d u r i n g a

b o u t o f i n t e r p r e t i n g

L o w

P o d h o r e c k i

& S p i e l h o l z

[ 8 ]

P r e v a l e n c e o f n e r v e

e n t r a p m e n t s b e t w e e n s i g n u s e r s

a n d

n o n s i g n u s e r s

N e r v e c o n d u c t i o n l a t e n c y

N o d i f f e r e n c e b e t w e e n s i g n e r s

a n d n o n - s i g n e r s - s u g g e s t S L I

r e l a t e d i n j u r i e s m a y b e m

o r e

r e l a t e d t o s o f t t i s s u e t r a u m

a

L o w

Q i n e t a l .

[ 1 3 ]

S

p e a k e r s p a c e

e

n v i r o n m e n t a l s t r e s s

E l e c t r o g o n

i o m e t r y ( k i n e m a t i c

o u t c o m e s )

I n c r e a s e d w r i s t m o t i o n ( v

e l o c i t y

a n d a c c e l e r a t i o n ) w i t h i n c

r e a s e d

s p e a k e r p a c e - S t r e s s s i g n

i f i c a n t l y

e f f e c t e d l e f t w r i s t m e a n v e l o c i t y

a n d a c c e l e r a t i o n

M e d i u m

R e g a l o e t a l .

[ 3 1 ]

m

u s c l e a c t i v a t i o n b e t w e e n s i g n

u s e r s a n d n o n s i g n u s e r s

G M E f o g n i t r o p e r r a e l c n U

G M E

t r e a t m e n t a n d a n a l y s i s p r e v e n t e d

m e a n i n g f u l i n f o r m a t i o n f r o m

b e i n g e x t r a c t e d

L o w

S h e a l y e t a l .

[ 3 2 ]

P

h y s i c a l e x p o s u r e

F r o n t a l p l a

n e v i d e o

( k i n e m a t i c o u t c o m e s )

K i n e m a t i c m a r k e r s ( j o i n t

a n g u l a r

v e l o c i t y a n d a c c e l e r a t i o n ) w e r e

a b o v e r e p o r t e d t h r e s h o l d l e v e l s

s e p a r a t i n g h i g h a n d l o w r i s k

g r o u p s

1 9 9 3 )

L o w




Table 3Summary of factors reported to impact MSD in SLI. The dependent measures

from Table 2 were categorized into the MSD impact categories described in thetable. The direction of the relationship is shown with an ↑ to denote an increasein the factors, while a decrease is denoted with a ↓. The impact on MSD riskis shown with a (+) to demonstrate an increase in MSD risk, while (−) is usedto demonstrate a decrease in MSD risk (i.e. an ↑ in subject matter knowledgedecreases (−) MSD risk). The shading distinguishes study types beginning withnarrative review (shaded grey), intervention (no shading), qualitative research(shaded grey), and quantitative research (no shading)

speaker pace and mechanical exposure through signingspeed, speaker pace has been kept as a separate factorin the analysis because the ultimate goal of the researchis to lead to interventions, and policy or practice inter-ventions for speaker pace may be different than inter-ventions for postural factors. Stress was used here todescribe psychological stress, psychosocial stress [14,15] and environmental stress [13]. Stress has also beendemonstrated to affect MSD development and progres-sion [16,17]. Similar to mechanical exposures, stress

likely contributes to MSD development directly, butstress may be affected by a number of situational andinterpreter specific factors [2,7,14,15].

Insuf ficient evidence was found to demonstrate theeffect on SLI MSD development of time-related fac-tors including lifetime exposure, exposure duration,rest breaks and micro-rest breaks. A strong body of research has demonstrated that exposure time and restplay a considerable role in MSD development andshould be managed accordingly (see review and guide




Table 4Level of evidence synthesis. This table describes all the factors that were reported to

impact MSD in SLI along withthe level of evidence in support of that factor. At least twomedium quality studies were required to achieve a limited evidence score. If fewer thantwo medium studies reported the result it was considered insuf ficient evidence (refer toTable 1 for level of evidence descriptions)

by Konz [18,19]). In this review, exposure durationand rest were kept as unique variables in the evidencesynthesis as they each represent independent units thatcan be affected with policy and practice changes (i.e.single exposure, or weekly duration limits, or manda-tory rest durations). However, when considered collec-

tively, thereweretwo medium [20,21]and two low [22,23] quality studies demonstrating that more rest (restbreaks or micro-rest breaks) decreased the risk of de-veloping MSD (considered limited evidence). Similar-ly, one medium quality study [24] and four low qualitystudies [23,25–27] showed that risk of injury increasedwith exposure time (single bout, weekly, or lifetime).These results suggest that more high quality researchbe geared toward understanding the work-to-rest rela-tionship within the context of SLI. More conclusiveresearch is necessary for guiding potential policy andpractice changes by AVLIC and RID and their interna-tional counterparts.

Many additional factors were linked to MSD riskamongst SLI, although the level of evidence is insuf fi-cient to substantiate them. These factors included workpressure, exaggerated sign style (signing big for a largeaudience, or small finger spelling for specific jargonrelated terms), gender, fear of injury, subject matter

knowledge, and general MSD awareness. Due to thelack of quality research in the area it is not possible atthis time to determine how much impact these factorsmay have on MSD in SLI. From a policy standpointmany of these factors represent practical and plausiblepathways to help mitigate risk. For example, a stan-dard health and safety contract with employers couldbe used to oblige employers to send preparation mate-rial to the interpreter in advance, allowing the SLI toimprovesubject matter knowledge in advance of an ap-pointment and relieve pressure related to a possible lackof topic knowledge. A contract could lay out rules forpresentations to ensure appropriate staging and sight




Fig. 2. A conceptual model to help describe the multi-factorial nature of MSD pathology development in SLI. The middle row represents thecascade of factors affecting tissue pathology. These factors may be influenced by situational factors (top row) and interpreter specific (bottomrow) factors. The model is not meant to describe or account for every potential injury pathway; rather it provides a more simple illustration todemonstrate how some work factors may impact other factors, which may impact injury risk.

lines, to reduce the need for exaggerated sign produc-tion. However in the absence of more conclusive in-formation about these potential factors, it may be dif fi-cult to justify the inclusion of such terms in contractualagreements. More high quality research is warrantedto improve our understanding of how these factors mayimpact MSDin SLI, and therebyenable evidence-based

policy.Throughout the review process it was evident that

SLIs are exposed to a variety of work situations in adiversity of complex environments. Each study de-scribed a host of situational and interpreter specific fac-tors that may contribute to MSD development in SLIs,some of which were researched, and some which re-main speculative, with limited research support. Tohelp understand the complex relationship between thevariety of factors described and MSD development, aconceptual model was developed (Fig. 2). The goal of the model is to present a simple graphic that can beused to guide future research and help demonstrate the

multi-factorial nature of injury development for prac-ticing interpreters, such as those registered with AVLICand RID. The model is comprised of three components:an injury section, a situational factors section, and anindividual interpreter section.

The injury section (center row in the model) de-

scribes how mechanical exposure created through theproduction of physical signs impacts the work respons-es of fatigue and stress, which may cascade into phys-ical effects of micro trauma and tissue injury. Thisbasic framework of cascading effects causing MSDpathology is adapted fromthe model presented by Arm-strong [28].

The situation factorscomponent (toprow in themod-

el) describes considerations such as speaker specific

factors, work demand factors and environmental fac-

tors. Each factor is considered to affect one or more

components within the injury section. For example, in-

creased speaker pace has been shown to increase joint

acceleration [13]. The variation in situation factors,

and the means to modify them, may differ between self-employed interpreters working in varied settings and

salaried interpreters potentially working in a uniform

setting.

The third row represents factors specific to the inter-

preter. These may include factors related to their indi-

vidual training and knowledgebase (sign style,ef ficien-

cy, etc.), their psychological and psychosocial state, in

addition to any personal anatomic factors. Again, each

factor is considered to impact one or more components

within the injury section. For example, an interpreter

with a larger cognitive capacity and improved ef ficien-

cy may be able to store a greater amount of an audible

message in working memory, allowing them to cogni-

tively produce a more ef ficient signed message using

fewer total signs and thus allowing them to take longer

micro rest breaks. More research is needed to under-

stand if this is indeed a mechanism to reduce mechani-

cal exposures in SLIs.

It is clear that the job of interpreting is associated

with MSD pathology. Numerous studies have identi-

fied a high prevalence of pain, discomfort, and injury

amongst this population. The challenge for this young

profession moving forward is how to mitigate these

risks appropriately to help build a healthy work force




of interpreters capable of handling the growing work-

load. The research review demonstrated a lack of highquality research from which to develop risk mitigation

strategies. However, the review highlighted several tar-

geted areas where appropriate intervention may help

mitigate MSD risks.

Work and rest – factors that figure in MSD preven-

tion across many domains–were not conclusively asso-

ciated with a change in SLI MSD risk, due in part to a

lack of quality research, and the diversity of duration

and rest time outcome measures used in those studies.

Future research on SLI should be directed towards bet-

ter understandingthe implications of exposure duration

and rest if work /rest schedules or exposure policies are

to be mandated. Currently both AVLIC and RID have90-minute maximum single-bout duration policies, yet

the research evidence for these is insuf ficient.

Limited evidence supports that increased speakerpace (high repetition), increased stress, and increased

mechanical exposure increase MSD pathology risk. In-

terventions in these areas are more complex than work-

to-rest interventions. The nature of the language con-

strains changes to sign mechanics and mechanical ex-

posures. Securing the cooperation of speakers is a sig-

nificant obstacle and potential added source of stress.

The conceptual model aims to capture the requisite

complexity of the SLI task and interactions among fac-tors associated with MSD pathology in the literature.

While it is not a quantitative model of injury, it may

be used to ensure that future research accounts for the

confounders present in this complex task, and encour-

age research consideration of both cognitive and phys-

ical factors. Interpreters and those working with inter-

preters may also use this model to visualize how differ-

ent work factors impact other work factors, which may

impact injury risk.

Acknowledgements

We are grateful for the immense practical assistance

of the Association of Visual Language Interpreters of

Canada (AVLIC). We would also like to thank RID for

their assistance in retrieving articles from the Journal

of Interpretation. Steven Fischer was supported by aNSERC PGS Doctoral award.

References

[1] Sanderson G (1987) Overuse syndrome among sign languageinterpreters. J Interpret 4, 73-78.

[2] Watson J (1987) Interpreter burnout. J Interpret 4, 79-85.[3] Sweeney M, Peterson M, O’Neil V (1994) Health hazard eval-

uation report: Ohio chapter, registry of interpreters for thedeaf. NIOSH Report number: HETA-92-0268-2477.

[4] Boocock MG, McNair PJ, Larmer PJ, Armstrong B, CollierM, Simmonds M, Garrett M (2007) Interventions for the pre-vention of and management of neck/upper extremity mus-culoskeletal conditions: a systematic review. Occup Environ

Med 64, 291-303.[5] Slavin RE (1995) Best evidence synthesis: An intelligent al-

ternative to meta-analysis. J Clin Epidemiol 48, 9-18.[6] Stedt JD (1989) Carpal Tunnel Syndrome: The risk to educa-

tional interpreters. Am Ann Deaf 134, 223-226.[7] Dean R, Pollard Jr R (2001) Application of demand-control

theory to sign language interpreting: Implications for stressand interpreter training. J Deaf Stud Deaf Educ 6, 1-14.

[8] Podhorodecki AD, Spielholz NI (1993) Electromyographic

study of overuse syndromes in signlanguage interpreters. ArchPhys Med Rehabil 74, 261-262.

[9] Marras W, Schoenmarklin R (1993) Wrist motions in industry.Ergonomics 36, 341-351.

[10] Remple D, Bach J, Gordon L, So Y (1998) Effects of forearmpronation/supination on carpal tunnel pressure. J Hand Surg

23A, 38-42.[11] Keir P, Bach J, Hudes M, Remple D (2007) Guidelines for

wrist posture based on carpal tunnel thresholds. Hum Factors

49, 88-99.[12] Hagberg M, Stenberg B, Sundelin G (1987) The use of sign

language as an aggravating factor in shoulder tendinitis, a casehistory of a deaf-mute cleaner. J Hum Ergo. 16, 173-178.

[13] Qin J, Marshall MM, Mozrall J, Marschark M (2008) Effectsof pace and stress on upper extremity kinematic responses insign language interpreters. Ergonomics 51, 274-289.

[14] Feuerstein M, Marshall L, Shaw WS, Burrell LM (2000) Mul-ticomponent intervention for work-related upper extremitydisorders. J Occup Rehabil 10, 71-83.

[15] Delisle A, Durand M-J, Imbeau D, Lariviere C (2007) Theeffects of two interventions on persistent pain: A multiplesingle-case study among sign language interpreters. Int J Ind

Ergon 37, 111-123.[16] Bongers PM, De Winter CR, Kompier MAJ, Hilderbrandt

VH (1993) Psychosocial factors at work and musculoskeletaldisease. Scand J Work and Environ Health 19, 297-312.

[17] Bongers PM, Kremer AM, ter Laak J (2002) Are psychophys-ical factors, risk factors for symptoms and signs of the shoul-der, elbow, hand/wrist?: A review of the epidemiological lit-erature. Am J Ind Med 41, 315-342.

[18] Konz S (1998a) Work/rest: Part 1 – Guidelines for the practi-tioner. Int J Ind Ergon 22, 67-71.

[19] Konz S (1998b), Work/rest: Part 2 – The scientific basis (kn-owledge base) for the guide. Int J Ind Ergon 22, 73-99.

[20] Feuerstein M, Fitzgerald TE (1992) Biomechanical factorsaffecting upper extremity cumulative trauma disorders in signlanguage interpreters. J Occup Med 34, 257-264.

[21] Delisle A, Lariviere C, Imbeau D, Durand M-J (2005) Physicalexposure of sign language interpreters: Baseline measures andreliability analysis. Eur J of Appl Physiol 94, 448-460.

[22] DeCaro JJ, Feuerstein M, Hurwitz TA (1992) Cumulativetrauma disorders among educational interpreters. Contributingfactors and intervention. Am Ann Deaf 137, 288-292.

[23] Johnson WL, Feuerstein M (2005) An interpreter’s interpre-tation: Sign language interpreters’ view of musculoskeletaldisorders. J Occup Rehabil 15, 401-415.




[24] Feuerstein M, Carosella AM, Burrell LM, Marshall L, De-Caro JJ (1997) Occupational upper extremity symptoms insign language interpreters: Prevalence and correlates of pain,function, and work disability. J Occup Rehabil 7, 187-205.

[25] Cohn L, Lowry RM, Hart S (1990) Overuse syndromes of the upper extremities in interpreters for the deaf. Orthopedics

13(2), 207-209.[26] Madden M (1995) The prevalence of occupational overuse

syndrome among Australian sign language interpreters. J Oc-

cup Health and Safety – Australia and New Zealand 11, 257-263.

[27] Scheuerle J, Guilford AM, Habal MB (2000) Work-relatedcumulative trauma disorders and interpreters for the deaf. Appl

Occup Environ Hyg 15, 429-434.[28] Armstrong TJ, Buckle P, Fine LJ, Hagberg M, Jonsson B, Kil-

bom A, Kuorinka I, Silverstein B, Sjogaard G, Vikari-JunturaER (1993) A conceptual model for work-related neck and up-

per limb musculoskeletal disorders. Scand J Work and Environ Health 19, 73-81.

[29] Meals RA, Payne W, Gaines R (1988) Functional demandsand consequences of manual communication. J Hand Surg

13A(5), 686-691.[30] Peper E, Gibney KH (1999) Psychophysiological basis for

discomfort during sign language interpreting. J Interpret , 11-18.

[31] Regalo SCH, Teixeira VR, Vitti M, Chaves TC, Hallak JEC,Bevilaqua-Grossi D, de Oliveira AS (2006) Assessment of themaximum voluntary arm muscle contraction in sign languagefor the deaf. Electromyogr Clin Neurophysiol 46, 229-233.

[32] Shealy J, Feuerstein M, Latko W (1991) Biomechanical anal-ysis of upper extremity risk in Sign Language Interpreting. J

Occup Rehabil 1, 217-225.[33] Smith SM, Kress TA, Hart WH (2000) Hand/wrist disorders

among sign language communicators. Am Ann Deaf 145, 22-25.

[34] Stedt JD (1992) Interpreter’s wrist. Repetitive stress injury and

carpal tunnel syndrome in sign language interpreters. Am Ann Deaf 137, 40-43.



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