KNR 342 Occupational Biomechanics

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KNR 342Occupational Biomechanics

• Dr. Steve McCaw
• 227B Horton
• 438-3804
• smccaw_at_ilstu.edu
• www.cast.ilstu.edu/mccaw

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Ergonomics Ergo work nomos natural laws

• Management labor recognize that injury and
  reduced performance reflect a mismatch between
• the worker
• Job demands
• the task
• the environment.

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Hierarchical Goals of Occupational Biomechanics

• Generate
• tolerable
• acceptable
• optimal
• working conditions

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Factors Affecting Performance Injury
People are different.
Individual
body size shape (anthropometrics)
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Performance Injury
Individual
body size shape (anthropometrics) fitness level
/ injury history
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Performance Injury
Individual
body size shape (anthropometrics) fitness level
/ injury history off-work activities
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Performance Injury
Individual
body size shape (anthropometrics) fitness level
/ injury history off-work activities psychologica
l status
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Psychology of Recovery
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Performance Injury
Individual
body size shape (anthropometrics) fitness level
/ injury history off-work activities psychologica
l status Motivation injury benefits social
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Performance Injury
Environment
physical layout psychological demands
The effect of stress to adverse health may be
analogous to that of cigarette smoking to lung
cancer. While most people who smoke do not get
lung cancer, most cases of lung cancer are
related to smoking. Kroemer, Kroemer
Kroemer-Elbert, 2001.
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Performance Injury
Environment
physical layout psychological demands Lighting,
visual aids Noise
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Performance Injury
Task
KAZIMIR MALEVICH Female reaper 1912The
Kustodiev Picture Gallery, Astrakhan
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At-risk occupations U.S. Bureau of Labor
Statistics, 1996

• 1. Truck driver.
• 2. Non-construction laborer.
• 3. Nursing aides and orderlies.
• 4. Janitors and cleaners.
• 5. Assemblers.
• 6. Construction laborers.
• 7. Carpenters
• 8. Stock handlers and baggers.
• 9. Cashiers
• 10. Cooks
• 11. Miscellaneous food preparation staff.

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Top 10causesof injury
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Performance Injury
Task
Speed of working Complexity of task Fit of
components
KAZIMIR MALEVICH Female reaper 1912The
Kustodiev Picture Gallery, Astrakhan
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Performance Injury
Individual
Task
Environment
Mismatch predisposes to Injury
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Nothing is static.
Simple model of accident causation. Oborne,
1982.
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Ergonomics

• Psychologists investigate mental function and the
  workplace
• human factors, cognitive factors
• Exercise physiologists evaluate metabolic,
  respiratory CV effects of prolonged, strenuous
  activities in industry
• work physiology

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Occupational Biomechanics

• Biomechanics
• apply laws of physics and engineering concepts to
  
• Describe motion undergone by various body
  segments
• kinematics
• Understand the forces acting on these segments
• kinetics

Biomechanics Science concerned with the
mechanical behavior of the NMS system and
component tissues when physical tasks are
performed
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Who Uses Occupational Biomechanics? YOU
Do. Will.

• Engineers
• Workplace design
• Process control
• Safety Managers
• Allied health providers
• Physicians
• Nurses
• Rehabilitation personnel
• PT, OT, AT

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Techniques of Biomechanics

• Kinematics - time and space variables.
• Displacement
• Velocity
• Acceleration
• Kinetics - force and energy variables
• F m a
• Ft mVf - mVi
• Fd 1/2 mV2 mgh

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Biomechanics Techniques

• Kinematics - time and space
• Displacement
• Velocity
• Acceleration
• Kinetics - force (torque) energy
• F m a
• Ft mVf - mVi
• Fd 1/2 mV2 mgh

Demands of the Task Environment
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Occupational Biomechanics

• complements psychological and physiological
  knowledge
• Considers physical interaction of worker, task
  workplace
• Basis of OSHA guidelines
• Focus is mechanical stress on the body

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Occupational Biomechanics

• complements psychological and physiological
  knowledge
• Considers physical interaction of worker, task
  workplace
• Basis of OSHA guidelines
• Focus is mechanical stress on the body

Force / Area
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Six Methodological Areas
Major Application Areas
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Objectives of Occupational Biomechanics
Maximize safety productivity

• Minimize fatigue overexertion
• Improve quality and quantity of output
• Minimize time lost to and cost of injury
  accident
• Minimize absenteeism and labor force turnover

Fit the Job to the Worker. Tools, layout,
organization, flow
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Need for Biomechanics Evaluation

• increased complexity of industrial and
  manufacturing processes
• rising costs
• health care, rehabilitation, insurance
• increase in litigation / bad PR stemming from
  injury
• new legislation (anticipated??)
• OSHA 2000 rejected 2001

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Knowledge of Occupational Biomechanics is used to

• Evaluate physical demands of existing jobs and
  workplaces
• Suggest alternative work methods
• scientific principle/basis for change
• Facilitate employee selection and placement
  procedures

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Social/legal support for occupational
biomechanics

• Hiring cannot discriminate on basis of
• age
• race
• gender
• disability
• but jobs must not provide undue risk for injury

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OSHA Act of 1970

• Employers are to provide employees with
• Competent fellow employees managers
• A safe working environment
• Knowledge of hazards
• Safety rules
• Safe tools

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Implementing a Program
Attitude
Employee - Self-help
Employer - Investment
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Safety must be accepted as

• Legally necessary
• Economically advantageous
• Ethically imperative

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Need for an Occupational Biomechanics Specialty

• Epidemiological support of occupational
  biomechanics
• Health and quality of life are greatly reduced
  for many because of musculoskeletal disorders
• acute
• chronic

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We want to encourage employers to take the high
road to safety - Joseph A. Dear Former
OSHA Administrator
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We want to encourage employers to take the high
road to safety and we will use our enforcement
program to preclude them from taking the low
road. - Joseph A. Dear Former OSHA
Administrator
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Dealing with injury creates a logistical
nightmare
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Event Sudden Force

• Trauma Type Impact
• Typical Medical Outcomes
• Contusion (bruise)
• Laceration (cuts)
• Sprain (ligament)
• Fracture (bone)
• Subluxation \ dislocation (joint)
• Concussion (brain)

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Event Repeated Motion

• Trauma Type Overexertion, overuse injury
• RMI repetitive motion injury
• RSI repetitive strain injury
• CTD cumulative trauma disease
• RMD Repetitive Motion Disorder
• OOD Occupational Overuse Disorder
• UECTD Upper Extremity Cumulative Trauma Disorder
  
• Vibration syndrome

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Event Volitional Activity

• Trauma Type Overexertion
• Typical Medical Outcomes
• Muscle strain
• Tendonitis inflamed tendon
• Tenosynovitis inflamed tendon sheath
• Myofascial Disorders
• Nerve Entrapment Disorders
• Low Back Pain
• Carpal Tunnel Syndrome

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Types of Injuries(Bureau of Labor Statistics,
1999)
Values 1000
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The Need for an Occupational Biomechanics
Specialty

• 1990
• 1.8 million disabling work injuries in US
• permanent impairment 600,000
• 72 of injuries of 3 kinds
• overexertion (31)
• collision (struck by or striking) (24)
• falls (17)

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Placebo effects and surgery for treatment of
overuse injuries.
Biomech-LJune 22, 2006

• Research has shown that arthroscopic debridement
  operations on the knee for osteoarthritis often
  provide little more than a placebo effect. Many
  patients report symptomatic relief after
  undergoing arthroscopy of the knee but it is not
  clear how the procedure achieves this result. A
  randomized controlled trial to evaluate the
  efficacy of arthroscopy for osteoarthritis of the
  knee showed that the outcomes after arthroscopic
  lavage or arthroscopic debridement were no better
  than those after a placebo procedure (Moseley et
  al, 2002).
• Does anyone know if anyone has done any similar
  research concerning common surgical treatments
  for overuse injuries? Hutson (1997) has cast
  doubt on the efficacy of many forms of medical
  treatment for overuse injuries (such as splinting
  a sore wrist rather than resting it) hence it
  would be interesting to know if the outcomes of
  surgery for carpal tunnel syndrome (i.e.
  decompression of the carpal tunnel) ever reflect
  a placebo effect (especially if this is merely
  due to rest after the operation).
• Regards,David McFarlane, Ergonomist, WorkCover
  Authority, New South Wales, Australia
• References1. J. Moseley, K. O'Malley, N.
  Petersen, T. Menke, B. Brody, D. Kuykendall, J.
  Hollingsworth, C. Ashton and N. Wray, (2002), "A
  Controlled Trial of Arthroscopic Surgery for
  Osteoarthritis of the Knee", New England Journal
  of Medicine, July 11, 2002, Volume 34781-88,
  Number 2. 
• 2. M. Hutson, (1997), "Work-Related Upper Limb
  Disorders Recognition and Management",
  (Butterworth-Heinemann Oxford).

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Job-related Injuries

• Bureau of Labor Statistics (for 1994)
• 705,000 (32) of illness causing missed work were
  overexertion \ repeated motion
• 367,000(52) were lifting related
• 65 affected the back
• median 6 days off work (mean 120 days)
  Interpret?
• 93,000 (13) were pushing/pulling related
• 52 affected the back
• median 7 days off work
• 69,000 (10) holding, carrying, turning objects
• 58 affected the back
• median 6 days off work

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At-risk occupations U.S. Bureau of Labor
Statistics, 19961999

• 3. Nursing aides and orderlies.
• 1. Truck driver.
• 2. Non-construction laborer.
• 5. Assemblers.
• 4. Janitors and cleaners.
• Registered Nurses
• 8. Stock handlers and baggers.
• 6. Construction laborers.
• 9. Cashiers
• Sales Supervisors and proprietors
• 7. Carpenters
• 10. Cooks
• 11. Miscellaneous food preparation staff.

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Cost of overuse/overexertion injuries to society
(1995)

• lost wages
• lost productivity
• administrative expenses
• health care costs

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Cost of overuse/overexertion injuries to society
(1995)

• Depends who you talk to
• Textbook (no source) 126 billion
• National Safety Council 119.4 billion
• NIOSH 13-20 billion
• California Workers Compensation Board
• 21,453 average cost
• National Council on Compensation Insurance
• 12,370 average RMI claim

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Cost of overuse/overexertion injuries to society
(1995)
Pantagraph, 7/18/06
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Cost of overuse/overexertion injuries to society
(1995)

• Depends who you talk to
• National Safety Council 119.4 billion
• NIOSH 13-20 billion
• California Workers Compensation Board
• 21,453 average cost
• National Council on Compensation Insurance
• 12,370 average RMI claim

Regardless of the estimate used, the problem is
large both in health and economic terms.
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Injured Worker Characteristics

• Men
• 66 of injury (55 of workforce)
• Age
• 25-44 57 of injury (54 of workforce)
• gt45 years 24 of injury (29 of workforce)
• Most workers gt 1 year service
• 25 injured gt 5 years service

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Forerunners of Overuse Disorders

• Rapid and often-repeated actions
• Exertion of finger, hand, or arm forces
• Pounding and jerking
• Contorted body joints
• Polished-by-use sections of the workplace or
  clothing custom-made padding
• Blurred outlines of the body owing to vibration
• The feeling of cold and the hissing sound of
  fast-flowing air

K, K K-E, 2001
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Simple interventions can be VERY effective.
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Goal understand biomechanics of awkward
posture
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Occupational Risk Factors FIT (Cumulative Trauma
Disorders)

• Mechanical Stress (Force / area)
• Frequency (Repetition)
• Intensity (Force exerted)
• Time (Duration of loading)

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Next the BIO portion

• Osteology
• study of bones.
• Arthrology
• study of joints.
• Myology
• study of muscles.
• Neurology
• study of nerves.

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Call it a night.