NECK AND UPPER EXTREMITY ERGONOMICS 101

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1 NECK AND UPPER EXTREMITY ERGONOMICS 101 UCSF Occupational Medicine CME March 11, 2017 Carisa Harris Adamson, PhD, PT, CPE I have no personal conflicts of interest to disclose. The UC Ergonomics Research & Graduate Training Program is supported by: Google Pentax Logitech Santos 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 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, Available at:

2 By Occupation Incidence of Work-Related Musculoskeletal Disorders in Private Industry, United, States, 2015 Occupation Laborers and freight handlers Nursing aides and orderlies Number of Incident Cases Incidence Rate per 10,000 Workers 21, , Janitors and cleaners 15, Heavy and tractor-trailer truck drivers 15, Emergency medical technicians/paramedics 3, Firefighters 5, Telecommunication line installers/repairers 2, By Body Region Work-Related Musculoskeletal Disorders (WMSDs) of the Neck, Back, and Upper Extremity, Washington State Workers Compensation Compensable (a) Claims, State Fund and self-insured, Incidence per Median Type 10,000 FTEs (b) Lost Workdays (c) Median Cost (d) All $11,183 Back $6,032 Shoulder $28,228 Rotator cuff syndrome (e) $37,835 Elbow/forearm $18,083 Epicondylitis (e) $19,484 Hand/wrist $14,166 Carpal tunnel syndrome (e) $17,536 Tendonitis (e) $15,721 Knee $14,245 Strong Evidence (++) Evidence(+) Insufficient (0) Evidence from Epidemiological Studies Force Repetition Awkward Static Combo Vibration Neck & Neck/Shoulder Shoulder Elbow Hand/Wrist Tendonitis Carpal Tunnel Syndrome Hand Arm Vibration Back Why injuries occur 2001 National Research Council Institute of Medicine report on MSDs and the workplace

3 Demand vs. Capacity 40 Acute Injury Load (kg) FORCE Unacceptable (Demand > Capacity) 10 Acceptable (Capacity > Demand) Repetitive Strain Injury, Fatigue Frequency (Lifts / minute) REPETITION Jim Potvin (2016) RECOVERY Demand EXERTION (FORCE) DURATION OF EXERTION FREQUENCY OF EXERTIONS (REPETITION) Jim Potvin (2016) Capacity Force production influenced by: Number of motor units activated Muscle fiber type Muscle architecture (PCSA) Muscle Length Velocity & Type of Contraction Muscle Fatigue Capacity Fatigue: decreased ability to generate force (%MVC) Symptoms: discomfort, pain, tremor, endurance phpapp01/95/10-motor-unit-sr al jpg?cb= Jim Potvin (2016)

4 Demand vs. Capacity Torque = Force x moment arm C of G Torque external = Torque internal Demand vs. Capacity NECK & SHOULDER MUSCULOSKELTAL DISORDERS NECK Upper Neck Tension Syndrome SHOULDER Impingement Syndrome biceps tendonitis Strong Evidence (++) Evidence(+) Insufficient (0) Evidence from Epidemiological Studies Force Repetition Awkward Static Combo Vibration Neck & Neck/Shoulder Shoulder Elbow Hand/Wrist Tendonitis Carpal Tunnel Syndrome Hand Arm Vibration Back

5 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: Time to Fatigue for Sustained Cervical Flexion Annual Incidence of pain >1week in office environment 34% Prolonged neck flexion and rotation Increase computer use [Chaffin 1973] 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): Shoulder Disorders Supraspinatus tendon gets impinged under coracoacromial arch Microtrauma of bicipital tendon (long) as it passes through the bicipital groove of humeral head

6 Time to Fatigue for Unsupported Reach Activities Van Rijn et al, 2010 Systematic Review (N=1739; n=17) 14 Cross Sectional 2 Prospective 1 Case-Control High Force (OR ) >10% MVC Lifting>20kg >10x/day High hand exertion >1hr/day o High Repetition (OR ) Shoulder movements Hand exertions (>2hrs/day) Hand arm vibration Working with hand above shoulder height Working High Psychosocial Demand (OR ) 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): Examples DISTAL UPPER EXTREMITY DISORDERS Elbow lateral epicondylitis medial epicondylitis Hand/Wrist six extensor compartments intersection syndrome three flexor sites stenosing tenosynovitis Entrapment Neuropathies Carpal tunnel syndrome Cubital tunnel syndrome Guyon's canal compression Hand-arm-vibration syndrome

7 Lateral & Medial Epicondylitis Strong Evidence (++) Evidence(+) Insufficient (0) Evidence from Epidemiological Studies Force Repetition Awkward Static Combo Vibration Neck & Neck/Shoulder Shoulder Elbow Hand/Wrist Tendonitis Carpal Tunnel Syndrome Hand Arm Vibration Back Biomechanical Exposure Systematic Review (N=633; n=13) on elbow disorders and work related factors LE associated with: Handling tools >1 kg (ORs of ) handling loads >20 kg at least 10 times/day (OR 2.6) repetitive movements >2 h/day (ORs of ) 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 ) 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: Biomechanical Exposure 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 and force associated with lateral epicondylitis (LE) for 40% AND o Power grip [HR=2.8; 95%CI: ] o 95%CI: ] o %time forceful exertion [HR=2.3; 95%CI: ] 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):

8 Hand/Wrist Tendinopathy Irritation of EPB & APL tendons or synovium under sheath Precision Lateral Pinch G Pad to Pad Pinch I Tip to Tip Pinch H vs. Power Power Grip A &C Spherical grip A Cylindrical grip C Hook grip J Lumbrical Grip Precision Grip D-F Increasing Strength Incidence of Hand/Wrist Tendinopathy Prospective Right Wrist Tendinosis Summary Extensor Right Side 28 MONTH FOLLOW UP N=413 Incid./ 100 PYs Right Side Incid./ 100 PYs Flexor Tendonitis Tendonitis Dorsal Flexor Carpi FCR > FDS > FCU Compartment Radialis Dorsal Flexor Carpi Compartment Ulnaris DC1(EPB/APL) >> Dorsal Flexor Digit. DC6 (ECU) > Compartment Sup DC3(EPL) or Dorsal Trigger DC4(ED) Compartment Finger Dorsal Compartment Dorsal Compartment Intersection Syndrome 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): Strong Evidence (++) Evidence(+) Insufficient (0) Evidence from Epidemiological Studies Force Repetition Awkward Static Combo Vibration Neck & Neck/Shoulder Shoulder Elbow Hand/Wrist Tendonitis Carpal Tunnel Syndrome Hand Arm Vibration Back

9 NIOSH UEMSD Consortium Study Determine exposureresponse relationship between physical exposure & UEMSDs 413 individuals in 4 sectors followed for up to 28 mos. Individual exposure assessment & physical exams Forceful exertion: Pinch ) X TWA = [( X 1 *p 1 ) + (X 2 *p 2 ) +. (X 4 *p 4 )] Biomechanical Exposure Hazard Ratio & 95% CI Force Measures: age-, gender-, and repetition(reps/min)-adjusted low VAS Tool Weight Normal. Peak Force % Time Heavy Pinch med high low med high low med high low med high Harris, C. Eisen, E., Goldberg, R., Krause, N., Rempel, D. Workplace and individual factors of Wrist Tendinosis among blue-collar workersthe San Francisco Study. Scan J Work Environ Health. 2011; 37 (2): Biomechanical Exposure Harris, C. Eisen, E., Goldberg, R., Krause, N., Rempel, D. Workplace and individual factors of Wrist Tendinosis among blue-collar workersthe San Francisco Study. Scan J Work Environ Health. 2011; 37 (2): Biomechanical Exposure Harris-Adamson C, Eisen EA, Goldberg R, You D, and Rempel D. The impact of posture on wrist tendinosis among blue- 2014;56(1):

10 Carpal Tunnel Syndrome 2 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 pheral nerve entrapment syndrome Nerve Compression - 4 weeks 0 mm Hg 70 mm Hg Mild perineural edema Epineurial fibrosis Perineurial thickening Loss of myelin Axon dropout Rempel DM, Diao E. Entrapment Neuropathies: pathophysiology and pathogenesis. Journal of Electromyography and Kinesiology. 2004:14; Keir PJ & Rempel DM. Pathomechanics of peripheral nerve loading: evidence in carpal Tunnel Syndrome. Journal of Hand Therapy. 2005:18(2); Strong Evidence (++) Evidence(+) Insufficient (0) Evidence from Epidemiological Studies Force Repetition Awkward Static Combo Vibration Neck & Neck/Shoulder Shoulder Elbow Hand/Wrist Tendonitis Carpal Tunnel Syndrome Hand Arm Vibration Back Personal Factors Covariate N=2474 (179 cases) HR [CI]* Female 1.30 [ ] Age ( 40 years) 2.84 [ ] 2 ) 1.67 [ ] Co-morbidities (DM, RA, thyroid) 0.95 [ ] Non-occupational hand activity 0.58 [ ] >3 hrs/wk *adjusted for gender, age, & BMI. 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.

11 Biomechanical Exposure WRIST 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 Biomechanical Exposure % TIME HAND EXERTION (any & forceful) REPETITION (any & forceful) 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 Biomechanical Exposure 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 not associated with CTS Total hand repetition rate % time any hand exertions Wrist posture [Forceful = grip] 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 ACGIH TLV for Hand Activity TLV for HAL Score = NPF / (10- HAL) % MVC high risk-needs analysis/ job design intermediate risk; surveillance and general controls recommended <AL (0.56): low risk

12 ACGIH TLV for HAL Exposure 1 N=2751 (n=186) HR* TLV for HAL 1.73 [ ] TLV for HAL 1.48 [ ] Exposure 2 N=2299 (n=84) IRR* TLV for HAL 1.95 [ ] TLV for HAL 2.70 [ ] Risk increased for those above the Action Limit current cutoffs might not be sufficiently protective 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): 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): Work Psychosocial Factors N Cases(n) HR 95% CI Psychological Demand Low ref High N Cases(n) HR 95% CI Decision Latitude Low ref High N Cases(n) HR 95% CI Job Strain Low (Low Demand & High Control) ref Active (High Demand & High Control) Passive (Low Demand & Low Control) High (High Demand & Low Control) *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 Nov;73(11): 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 [ ] 0.83 [ ] 2 ) 1.23 [ ] Rheumatoid Arthritis 1.85 [ ] High Job Strain (High Demand, Low Control) 2.38 [ ] *adjusted for gender, age, BMI & study site Biomechanical Exposures Exposure N=340 (n=178) HR* Pace Change Hal Scale 1.87 [ ] Hal Scale > [ ] % time in All Exertions % 0.81 [ ] % time in All Exertions >76% 1.96 [ ] Lost Time Total Repetition Rate 2.33 [ ] Total Repetition Rate > [ ] Forceful Repetition Rate 2.23 [ ] Forceful Repetition Rate > [ ] *All models adjusted for gender, age, BMI, study site & non-overlapping exposures

13 Biomechanical Exposures Exposure N=365 (n=118) HR* Job Change Hal Scale 3.45 [ ] Hal Scale > [ ] Total Repetition Rate 2.24 [ ] Total Repetition Rate > [ ] % time in All Exertions 1.27 [ ] % time in All Exertions >76% 2.76 [ ] % time in Forceful Exertions 1.27 [ ] % time in Forceful Exertions >28% 2.76 [ ] *All models adjusted for gender, age, BMI, study site & non-overlapping exposures Summary Being female or having RA increased risk Increasing age and BMI did NOT increase risk of disability but did increase risk for CTS High job strain increased risk of CTS and disability Pain was protective for time lost Physical factors had strongest associations with job change (vs. pace change or lost time) Measures of both forceful hand activity and repetition were associated with work disability Mushroom Growing Stone Manufacturing Milk and Dairy Production Chair Manufacturing 51 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.

14 Hand Arm Vibration Syndrome Risk Factors Vibration (ISO Standards ) o Magnitude o Frequency o Direction Worker o Exposure Duration o o Contact Location o Applied Force o Temperature Controls Source Control o Reduce vibration level Path Control o Limit exposure time Receiver Control o Vibration damping apparel o Reduce other risk factors Conclusion Injury 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 Exertion Forceful 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 & Comments Carisa.Harris-Adamson@ucsf.edu 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

15 Question #2 Total 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