NECK AND UPPER EXTREMITY ERGONOMICS 101...Tendonitis(e) 3.4 95 $15,721 Knee 10.1 56 $14,245 Work-Related Musculoskeletal Disorders (WMSDs) of the Neck, Back, and Upper Extremity, Washington

NECK AND UPPER EXTREMITY

ERGONOMICS 101UUCSF Occupational Medicine CME

March 11, 2017Carisa Harris Adamson, PhD, PT, CPE

I have no personal conflicts of interest to disclose.

The UC Ergonomics Research & Graduate Training Program is supported by:

GooglePentax

LogitechSantos Human

Why Ergonomics Today?U.S. Companies Pay $62 Billion Per Year for Workplace Injuries

$16 billion direct costs from WMSDs

Indirect costs are 2-5 times greater

The annual cost to U.S. business of lost-time workplace injuries is greater than the GDP of 91 countries

http://www.lco-cdo.org/vulnerable-workers-final-report.pdf

Incidence & Prevalence

356,910 WMSDs* in private industry in the United States *

incidence rate of 29.8 per 10,000 full-time workers

median of 12 days away from work

accounted for 32% of all injuries and illnesses reported to BLS

Definition of WMSDs:• A pinched nerve; herniated disc; meniscus tear; sprain, strain, or tear; hernia; pain,

swelling, and numbness; carpal tunnel syndrome and tarsal tunnel syndrome; Raynaud's syndrome and Raynaud’s phenomenon; musculoskeletal system and connective tissue diseases and disorders, AND

• overexertion …repetitive motion…. multiple exertions or vibration.

Bureau of Labor Statistics. Nonfatal Occupational Injuries and Illnesses Requiring Days Away From Work, 2015. Available at: http://www.bls.gov/news.release/osh2.nr0.htm.

By Occupation

OccupationNumber of Incident

CasesIncidence Rate per

10,000 Workers

Laborers and freight handlers21,990 111.0

Nursing aides and orderlies19,360 180.5

Janitors and cleaners15,810 102.6

Heavy and tractor-trailer truck drivers 15,320 95.6

Emergency medical ttechnicians/paramedics 3,980 187.4

Firefighters5,630 168.5

Telecommunication line iinstallers/repairers 2,190 224.6

Incidence of Work-Related Musculoskeletal Disorders in Private Industry, United, States, 2015

https://www.cdc.gov/niosh/docs/97-141/pdfs/97-141.pdf

By Body Region

Type

Incidence per

10,000 FTEs(b)

Median

Lost Workdays(c) Median Cost(d)

All 90.0 56 $11,183

Back 40.8 35 $6,032

Shoulder 14.8 129 $28,228

Rotator cuff syndrome(e) 6.2 192 $37,835

Elbow/forearm 5.3 116 $18,083

Epicondylitis(e) 1.6 129 $19,484

Hand/wrist 15.3 79 $14,166

Carpal tunnel syndrome(e) 6.4 100 $17,536

Tendonitis(e) 3.4 95 $15,721

Knee 10.1 56 $14,245

Work-Related Musculoskeletal Disorders (WMSDs) of the Neck, Back, and Upper Extremity, Washington State Workers’ Compensation Compensable(a) Claims, State Fund and self-insured, 2002–2010

EEvidence from Epidemiological StudiesStrong EEvidence (++)Evidence(+)IInsufficient (0)

Force Repetition Awkward Posture

Static Posture

Combo Vibration

Neck & Neck/Shoulder + + ++ . . 0Shoulder 0 + + . . 0Elbow + 0 0 . ++ .Hand/WristTendonitis + + + . ++ +Carpal Tunnel Syndrome + + 0 . ++Hand Arm Vibration . . . . . ++Back ++ . + 0 . ++


WWhy injuries occur

2001 National Research Council Institute of Medicine report on MSDs and the workplace

DDemand vs. Capacity

40

30

20

10

0

0 2 4 6 8 10 12 14 16 18

Load(kg)

Frequency (Lifts / minute)REPETITION

Unacceptable(Demand > Capacity)

Acceptable(Capacity > Demand)

Acute Injury

Repetitive StrainInjury, Fatigue

© Jim Potvin (2016)

FORCE

DDemand

EXERTION(FORCE)

FREQUENCY OF EXERTIONS (REPETITION)

DURATION OFEXERTION

RECOVERY

© Jim Potvin (2016)

CCapacity

Force production influenced by:

Number of motor units activated

Muscle fiber type

Muscle architecture (PCSA)

Muscle Length

Velocity & Type of Contraction

Muscle Fatigue

CCapacityFatigue: decreased ability to generate force (%MVC)

Symptoms: discomfort, pain, tremor, endurance

© Jim Potvin (2016)https://image.slidesharecdn.com/10motorunitsr20022013-al-131106170713-phpapp01/95/10-motor-unit-sr2002-2013-al-11-638.jpg?cb=1383757997

C of G

Demand vs. Capacity

Torque = Force x moment arm

Torque external = Torque internal

DDemand vs. Capacity

NECK & SHOULDER MUSCULOSKELTAL

DISORDERSNECK

UUpper Neck Tension Syndrome

SHOULDERImpingement Syndrome

biceps tendonitis



Static Posture

Combo Vibration

Neck & Neck/Shhoulder + + ++ . . 0Shoulder 0 + + . . 0Elbow + 0 0 . ++ .Hand/WristTTendonitis + + + . ++ +Carpal Tunnel SSyndrome + + 0 . ++Hand Arm VVibration . . . . . ++Back ++ . + 0 . ++


Neck Tension Syndrome

•Aching discomfort at the base of neck/upper back- can be unilateral•Headaches due to radiating pain •Intermittent neck muscle spasms •Tenderness to palpation

• IR = 31.5 per 10,000 FTEs

• Among a large Danish Cohort Study:

o 12 month prevalence 31%

o Point prevalence: 21%o Prevalence Chronic

Symptoms >3mos): 14%

Picavet HSJ, Schouten JSAG. Musculoskeletal pain in the Netherlands: prevalence, consequences and risk groups, the DMC study. Pain.2003;102:167-78.

[Chaffin 1973]

Time to Fatigue for Sustained Cervical Flexion

• Annual Incidence of pain >1week in office environment 34%

• Prolonged neck flexion and rotation

• Increase computer use

Palmer & Smedley, 2007

Systematic Review (N=136; n=21)

Studies included

– 15 Cross-Sectional– 4 prospective– 2 Case-Control

• Static Neck Loading

• Repetitive or forceful shoulder work

• High Job Strain

Palmer KT & Smedley J. Work relatedness of chronic neck pain with physical findings—a systematic review. Scand J Work Environ Health. 2007;33(3):165-191.

Shoulder DisordersSupraspinatus tendon gets impinged under coracoacromial arch

Microtrauma of bicipital tendon (long) as it passes through the bicipital groove of humeral head

Time to Fatigue for Unsupported Reach Activities

Van Rijn et al, 2010Systematic Review (N=1739; n=17)

– 14 Cross Sectional– 2 Prospective– 1 Case-Control

High Force (OR 2.8 - 4.2)– >10% MVC– Lifting>20kg >10x/day– High hand exertion >1hr/day

oHigh Repetition (OR 1.04 - 4.7)

– Shoulder movements– Hand exertions (>2hrs/day)– Hand arm vibration– Working with hand above shoulder height– Working °

High Psychosocial Demand (OR 1.5 - 3.19)vanRijn RM, Huissted BMA, Koes BW, Burdorf A. Associations between work-related factors and specific disorders of the shoulder- a systematic review of the literature. Scand J Work Environ Health 2010;36(3):189-201.

Examples

DISTAL UPPER EXTREMITY DISORDERS

EElbowlateral epicondylitismedial epicondylitis

Hand/Wristsix extensor compartments

intersection syndromethree flexor sites

stenosing tenosynovitis

Entrapment NeuropathiesCarpal tunnel syndrome

Cubital tunnel syndrome Guyon's canal compression

Hand-arm-vibration syndrome

Lateral & Medial Epicondylitis



Static Posture

Combo Vibration



Biomechanical Exposure

Systematic Review (N=633; n=13) on elbow disorders and work related factors

LE associated with:

– Handling tools >1 kg (ORs of 2.1–3.0)– handling loads >20 kg at least 10 times/day (OR 2.6) – repetitive movements >2 h/day (ORs of 2.8–4.7)

ME associated with:

– Handling loads >5 kg (2 times/min at minimum of 2 h/day), – handling loads >20 kg at least 10 times/day, – high hand grip forces for >1 h/day, – repetitive movements for >2 h/day (ORs of 2.2–3.6) – working with vibrating tools >2 h/day (OR 2.2)

vanRijn RM, Huissted BMA, Koes BW, Burdorf A. Associations between work-related factors and specific disorders at the elbow: a systematic review of the literature. Rheumatology. 2009;48:528-536.

611 people followed for up to 3.5 years

12 manufacturing and service sectors in WA

Case Criteria: pain at LE with resisted wrist extension & symptoms

IR = 4.91 per 100 person-years

Posture and force associated with lateral epicondylitis (LE)• ° for 40% AND

o Power grip [HR=2.8; 95%CI: 1.35-5.77]o 95%CI: 1.19-5.24]o %time forceful exertion [HR=2.3; 95%CI: 1.09-4.66]

Older exposed workers (35-64 yo) were 4x more likely to get LE

Engaging in hobbies/sports with high hand force did not increase risk

Fan JZ, Silverstein BA, Bao S, Bonauto DK, Howard NL, and Smith CK. The association between combination of hand force and forearm posture and incidence of lateral epicondylitis in a working posture. Human Factors. 2014;56(1):151-165.


Hand/Wrist Tendinopathy

Irritation of EPB & APL tendons or synovium under sheath

Precision vs. PowerPower Grip A &C

Spherical grip A

Cylindrical grip C

Hook grip J

Lumbrical Grip

Precision Grip D-F

Lateral Pinch G

Pad to Pad Pinch I

Tip to Tip Pinch H

Increasing Strength

Prospective Right Wrist Tendinosis

Summary

28 MONTH FOLLOW UP N=413

Right Side

Incid./ 100 PYs

Right Side

Incid./100PYs

Extensor Tendonitis 22 4.56

Flexor Tendonitis 11 2.24

Dorsal Compartment 1 13 2.68

Flexor Carpi Radialis 7 1.42


Flexor Carpi Ulnaris 0 0.00


Flexor Digit.Sup. 5 1.01


Trigger Finger 2 0.40

Dorsal Compartment 5 0 0.00Dorsal

Compartment 6 4 0.81Intersection

Syndrome 0 0.00

Incidence of Hand/Wrist Tendinopathy

Harris, C. Eisen, E., Goldberg, R., Krause, N., Rempel, D. “Workplace and individual factors of Wrist Tendinosis among blue-collar workers- the San Francisco Study.” Scan J Work Environ Health. 2011; 37 (2): 85-98.

FCR > FDS > FCU

DC1(EPB/APL) >> DC6 (ECU) > DC3(EPL) or DC4(ED)



Static Posture

Combo Vibration



NIOSH UEMSD Consortium StudyDetermine exposure-response relationship between physical exposure & UEMSDs413 individuals in 4 sectors followed for up to 28 mos.Individual exposure assessment & physical examsForceful exertion:

Pinch )

XTWA = [( X1*p1) + (X2*p2) + …. (X4*p4)]

0

1

2

3

4

5

6

7

8

9

10

Haz

ard

Rat

io &

95%

CI

lowVASmed high low

Tool Weightmed high low

Normal. Peak Forcemed high low

% Time Heavy Pinchmed high

Force Measures: age-, gender-, and repetition(reps/min)-adjusted


Harris, C. Eisen, E., Goldberg, R., Krause, N., Rempel, D. “Workplace and individual factors of Wrist Tendinosis among blue-collar workers-the San Francisco Study.” Scan J Work Environ Health. 2011; 37 (2): 85-98.

Harris, C. Eisen, E., Goldberg, R., Krause, N., Rempel, D. “Workplace and individual factors of Wrist Tendinosis among blue-collar workers-the San Francisco Study.” Scan J Work Environ Health. 2011; 37 (2): 85-98.


Harris-Adamson C, Eisen EA, Goldberg R, You D, and Rempel D. The impact of posture on wrist tendinosis among blue-2014;56(1):143-150.


Carpal Tunnel Syndrome2 million outpatient visits for CTS

Over 400,000 outpatient carpal tunnel release surgeries per year

50% 1 month lost time

11% lost or changed jobs

Most common peripheral nerve entrapment syndrome

pheral nerve entrapment

70 mm Hg0 mm Hg

Nerve Compression - 4 weeks

Mild perineural edema Epineurial fibrosisPerineurial thickeningLoss of myelinAxon dropout

Rempel DM, Diao E. Entrapment Neuropathies: pathophysiology and pathogenesis. Journal of Electromyography and Kinesiology. 2004:14; 71–75Keir PJ & Rempel DM. Pathomechanics of peripheral nerve loading: evidence in carpal Tunnel Syndrome. Journal of Hand Therapy. 2005:18(2);259-269.



Static Posture

Combo Vibration



Covariate N=2474 (179 cases) HR [CI]*Female 1.30 [0.98-1.72]Age ( 40 years) 2.84 [1.85-4.37]

2) 1.67 [1.26-2.21]Co-morbidities (DM, RA, thyroid) 0.95 [0.62-1.44]Non-occupational hand activity 0.58 [0.41-0.82]

>3 hrs/wk

*adjusted for gender, age, & BMI.

Personal Factors

Harris-Adamson C, Eisen EA, Dale AM, Evanoff B, Hegmann KT, Thiese MS, Kapellusch J, Garg A, Burt S, Silverstein B, Bao S, Merlino L, Gerr F, Rempel D. Personal and workplace psychosocial risk factors for carpal tunnel syndrome: a pooled study cohort: author response. Occup Environ Med. 2014;71(4):303-4.

WWRIST POSTURE PEAK HAND FORCE


Harris-Adamson C, Eisen EA, Kapellusch J, Garg A, Hegmann KT, Thiese MS, Dale AM, Evanoff B, Burt S, Bao S, Silverstein B, Merlino L, Gerr F, Rempel D. Biomechanical risk factors for carpal tunnel syndrome: a pooled study of 2474 workers. Occup Environ Med. 2015;72(1):33-41



% TIME HAND EXERTION(any & forceful)

REPETITION(any & forceful)

Risk of CTS increases linearly with increasing age and increasing BMI

Biomechanical factors associated with CTS• Peak hand force • Forceful hand repetition rate (>3 exertions/min)• % time in forceful hand exertions (> 11%)

Biomechanical factors nnot associated with CTS• Total hand repetition rate• % time any hand exertions• Wrist posture

[Forceful = grip]



ACGIH TLV for Hand Activity

high risk-needs analysis/ job design

intermediate risk; surveillance and general controls recommended

<AL (0.56): low risk

TLV for HAL Score = NPF / (10- HAL)

% M

VC

Exposure1 N=2751 (n=186) HR*TLV for HAL 1.73 [1.19-2.5]TLV for HAL 1.48 [1.02-2.13]

Exposure2 N=2299 (n=84) IRR*TLV for HAL 1.95 [1.21-3.16]TLV for HAL 2.70 [1.48-4.91]

Risk increased for those above the Action Limit –current cutoffs might not be sufficiently protective

ACGIH TLV for HAL

1 Kapellusch JM, Gerr FE, Malloy EJ, Garg A, Harris-Adamson C, Bao SS, Burt SE, Dale AM, Eisen E, Evanoff BA, Hegmann KT, Silverstein BA, Thiese MS, and Rempel D. Exposure-Response Relationships for the ACGIH TLV for Hand Activity Level: Results from a Pooled Data Study of Carpal Tunnel Syndrome. Scand J Work Environ Health. 2014;40(6):610-20.

2 Bonfiglioli R, Mattioli S, Armstrong TJ, Graziosi F, Marinelli F, Farioli A, Violante FS. Validation of the ACGIH TLV for hand activity level in the OCTOPUS cohort: a two-year longitudinal study of carpal tunnel syndrome. Scand J Work Environ Health 2013;39(2):155-163.

Work Psychosocial FactorsN Cases(n) HR 95% CI

Psychological Demand 1538 102Low 41 1.00 refHigh 61 1.38 0.94-2.05

N Cases(n) HR 95% CIDecision Latitude 1530 101

Low 43 1.00 refHigh 58 0.85 0.57-1.27

N Cases(n) HR 95% CIJob Strain 1527 101

Low(Low Demand & High Control)

28 1.00 refActive

(High Demand & High Control)30 1.29 0.76-2.18

Passive(Low Demand & Low Control)

13 1.06 0.55-2.05High

(High Demand & Low Control)30 1.51 0.91-2.52

*Adj for age gender, BMI, study site

Harris-Adamson C, Eisen EA, Neophytou A, Kapellusch J, Garg A, Hegmann KT, Thiese MS, Dale AM, Evanoff B, Bao S, Silverstein B, Gerr F, Burt S, Rempel D. Biomechanical and psychosocial exposures are independent risk factors for carpal tunnel syndrome: assessment of confounding using causal diagrams. Occup Environ Med. 2016 Nov;73(11):727-734.

Are Predictors of Work Disability Different?• Defined as (SF-12 & DASH):

– Pace/Quality Change due to hand symptoms,– Lost Time due to hand symptoms, or– Job Change due to hand symptoms

Covariate HR

Female 1.75 [1.23-2.5]

0.83 [0.59-1.15]

2) 1.23 [0.80-1.87]

Rheumatoid Arthritis 1.85 [1.04-3.26]

High Job Strain(High Demand, Low Control) 2.38 [1.03-5.51]*adjusted for gender, age, BMI & study site

Biomechanical ExposuresExposure N=340 (n=178) HR*

PPace ChangeHal Scale 1.87 [1.19-2.94]Hal Scale>6 1.69 [0.97-2.93]

% time in All Exertions % 0.81 [0.50-1.31]% time in All Exertions>76% 1.96 [1.20-3.20]

Lost TimeTotal Repetition Rate 2.33 [1.02-5.34]Total Repetition Rate>24 2.16 [0.97-4.79]

Forceful Repetition Rate 2.23 [1.01-4.95]Forceful Repetition Rate>8 1.83 [0.88-3.77]

*All models adjusted for gender, age, BMI, study site & non-overlapping exposures

Exposure N=365 (n=118) HR*

JJob ChangeHal Scale 3.45 [1.60-7.43]Hal Scale>6 3.25 [1.46-7.25]

Total Repetition Rate 2.24 [1.13-4.44]Total Repetition Rate>24 2.47 [1.21-5.06]

% time in All Exertions 1.27 [0.65-2.48]% time in All Exertions>76% 2.76 [1.35-5.66]

% time in Forceful Exertions 1.27 [0.65-2.48]% time in Forceful Exertions>28% 2.76 [1.02-4.05]

*All models adjusted for gender, age, BMI, study site & non-overlapping exposures

Biomechanical Exposures

SummaryBeing female or having RA increased risk

Increasing age and BMI did NOT increase risk of disability but did increase risk for CTSHigh job strain increased risk of CTS anddisability

Pain was protective for time lost

Physical factors had strongest associations with job change (vs. pace change or lost time)

MMeasures of both forceful hand activity and repetition were associated with work disability

51

Milk and Dairy Production Chair Manufacturing

Mushroom Growing Stone Manufacturing

Hand Arm Vibration Syndrome

Changes in sensory perception which can lead to permanent numbness of fingers, muscle weakness and, in some cases, bouts of white finger.

Hand Arm Vibration Syndrome

RRisk FactorsVibration (ISO Standards 2631-5349)

o Magnitude

o Frequency

o Direction

Worker

o Exposure Duration

o Posture

o Contact Location

o Applied Force

o Temperature

ControlsSource Control

o Reduce vibration level

Path Controlo Limit exposure time

Receiver Controlo Vibration damping apparel

o Reduce other risk factors

ConclusionInjury occurs when (work) demand > (worker) capacity

Even low physical demand for long periods of time can exceed a workers capacity (ie., result in fatigue)

Force is an important risk factor for MSDs and can be measured in various ways:

Peak Force% time spent in Forceful ExertionForceful Repetition Rate

The ACGIH TLV for HAL is not adequately protective of workers

Risk factors associated with the severity of an UEMSD (work disability) may differ than those associated with its incidence

Questions & Commentshttp://ergo.berkeley.edu

[email protected]

Question #1

According to the Bureau of Labor Statistics, work related musculoskeletal disorders:

a) Have an incidence rate of 3 per 10,000 full-time workers

b) Have a low severity and rarely require time away from work

c) accounted for approximately one third of all injuries and illnesses reported to BLS

d) None of the above

Question #2Total repetition rate alone is an important risk factor for the occurrence of distal upper extremity musculoskeletal disorders such as wrist tendinitis and carpal tunnel syndrome.

a) TRUE

b) FALSE

Question # 3

In a recent large cohort study in the United States, the following exposure(s) were found to be associated with an increased risk of Carpal Tunnel Syndrome:

a) Spending more than 11% time in forceful hand exertion (Pinch>1kg or grip>4kg)

b) Forceful repetition rate >3/minute

c) -10 Scale (0 to 10)

d) All of the above

e) None of the above

Documents

NECK AND UPPER EXTREMITY ERGONOMICS 101...Tendonitis(e) 3.4 95 $15,721 Knee 10.1 56 $14,245 Work-Related Musculoskeletal Disorders (WMSDs) of the Neck, Back, and Upper Extremity, Washington