Transcript Presentation by Dr Addley

Ergonomic Issues in
the Courtroom
Judicial Studies Board for Northern Ireland
29th May 2007
Dr Ken Addley
Director NICS OHS
www.nicsohs.gov.uk
Outline
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The back, posture, seats and sitting
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Computers and writing
Evolution – the Computer Age
The Vertebral Column
General Characteristics
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Formed from 26 irregular bones
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Axial support of trunk
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Surrounds and protects spinal cord
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Provides attachment points for ribs and
muscles of back
The Spine
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Cervical is the neck area
made up of 7 vertebrae and
curved inward or lordosis
Thoracic is mid-back with 12
vertebrae and has outward
curve or kyphosis
Lumbar area is lower back
with 5 vertebrae and is
curved inward or lordosis
Sacrum is below lumbar and
is solid mass of bone.
Anatomy: Soft Tissues
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Nerves branch off the spinal cord.
Ligaments are small, non-elastic bands that
connect to the discs and vertebrae, lending
support and stability to the spine.
Muscles have strong attachments to the
vertebrae along the entire length of the spine strongest in their mid-range position
Anatomy: Bones & Discs
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Bony vertebrae;
Facet Joints – 20%
weight
Discs – 80% weight
T11
T12
Vertebral Body
L1
L2
Spinal Cord
L3
L4
Intervertebral Disc
L5
Back Pain
Low Back Pain
•
affects 7 out of 10 people
•
commonest at age 35-55 yrs
•
10 Million working days lost
•
£481 million cost to NHS
•
£5 billion cost to industry
Risk Factors for Back Pain
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Increase force/stress
Repetitive Motion/twisting/Forward bending
Poor or improper lifting techniques
Poor posture
Poor Job design
Deconditioned/Poor physical fitness
Overweight
Tall stature
Common Back Problems
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Strains and sprains
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Facet joint pain
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Disc erosion
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Sciatic nerve impingement
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Herniated discs
Strains and Sprains
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Commonest cause of Low Back Pain
A pull on the soft muscle fibres causing bruising
inside the muscle.
Excessive pressure on the joints and those
ligaments attached to the joints.
Symptoms - stiffness, pain & aching, loss of
mobility.
Disc Problems (1)
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Acute - excessive and unusual stress and
strain forces on the back.
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Chronic - ageing, wear and tear and past
injury (Degenerative Disc Disease):
-
35% Healthy Male Volunteers
have significant DDD Paajenan et al
- 90% people age >50 have DDD
Miller et al
Disc Problems (2)
Herniated / Bulging Disc
Posture
Lumbar Disc Pressures
Mechanics: Poor Posture
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Spending long periods of time in abnormal
positions is stressful and damaging to the spine.
With increased lumbar lordosis, facet joints are
under increased pressure, nerve root spaces
become smaller, and muscle and ligaments are
shortened.
Means that the spine’s normal curves are
exaggerated or decreased creating stresses and
strains in the tissues.
Ideal Posture
The ideal posture is governed by:
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The chair
The task
The person
Sitting habits
The Chair
Low Back Support
Chair Height
Adjust or use foot rest
Chair Height
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Feet flat on floor
May need a foot rest
Thighs parallel to the
ground
Or knees slightly
lower than hips
Seat Pan Depth
Incorrect
Too Long: can cut off
circulation
Incorrect
Too Short: does not
provide enough support
Seat Pan Depth
1-2 inches from back
of knees to front of
seat
Correct
Ankles Tucked
Leaning forward
One size doesn’t fit everyone!
Adjust the chair to suit
A Good Ergonomic Chair
Well-designed and adjustable
Provides support to the back, legs, buttocks
and arms, while reducing exposure to
awkward postures, contact stress and
forceful exertions.
The Task
The Task
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Not unduly repetitive
No fixed, awkward or rigid postures
Tolerable working environment
Equipment ergonomically designed
Pace of work manageable
Adequate training
Task matched to the individual
The Person
The Person
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Trained and competent
Not anxious or tensed
Complies with safe system of work
Adjustment for disability
Seek help, advice or guidance
Sitting
Pick the Better Posture
Sitting geometry
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In unsupported chair (no back)
- the spine tends to flatten.
With a lumbar support
- the spine tends to retain
its natural shape.
Sitting in a chair place your forearm in the curve
of your lower back and sit back in your seat this
gives you an idea of a good sitting posture
Sitting & low back pain
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Some research shows a relationship between
low-back pain and prolonged sitting. Others
do not.
Drivers who sit longer than 3.5 hours/day
have a 3x increase in risk of disc herniation.
HSE recommends 15 min break per hour for
computer operators.
Bad Posture: Sitting
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Slumping in chairs.
Sitting with legs folded to one side.
Sitting with ankles crossed.
Slipping down the seat.
Persistently leaning forward.
Sitting on edge of seat
Prolonged sitting –
do stretches throughout the
day to keep your muscles
flexible and avoid injury.
Computers & Writing
The Digital Courtroom
V HS
DV D
Available Resources
1. Document Camera
2. Touch Screen Annotator
3. Laptop Computer Video Hookup
4. Audio/Video playback
5. Touch Screen Annotator
1
2
3
Ergonomically Correct
Work Station
Head Level
Line of Sight
Shoulders Relaxed
Wrists straight
Elbows at Sides
Low Back Supported
Feet Supported
Work Surface Height
Normal Working Area
Musculoskeletal
Problems
Musculoskeletal Disorders
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Common self-reported workrelated illness
Major reason for seeking
healthcare
Major reason for work absence
- 10 million days/yr
- ave time off 18 days
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Mostly no objective pathology
Upper Limb Disorders (1)
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A variety of soft tissue injuries affecting the
muscles, tendons and nerves of the hands,
arms, shoulders and neck
If connected to work, also known as:
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Work related Upper Limb Disorder (WRULD)
Repetitive Strain Injury (RSI)
Cumulative Trauma Disorder (CTD)
Occupational Overuse Syndrome (OOS)
Upper Limb Disorders (2)
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Carpel tunnel syndrome
Cubital tunnel syndrome
Thoracic outlet syndrome
Raynaud’s syndrome (white
finger)
Rotator cuff syndrome
DeQuervain’s disease
Tendinitis
Tenosynovitis
Trigger finger
Ganglion cyst
Upper Limb Disorders (3)
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Historically thought to be caused by repetitive
movements of hands or arms, usually at speed
and for prolonged periods ("dynamic loading")
Later, awkward/fixed postures ("static loading")
Importance of "non-physical" factors recently
recognised by HSE.
Use of keyboards and mouse devices
Use of Keyboard and Mouse (1)
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Keep your fingers relaxed.
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Use a soft touch on the keyboard instead of
pounding keys with unnecessary force.
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Grasp the mouse gently – move using elbows
not wrists.
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Avoid holding a pen or anything else in your
hands while you type or use the mouse.
Use of Keyboard and Mouse (2)
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Relax your fingers and hands between bursts of
typing or mousing using a flat, neutral straight
wrist posture.
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Don't rest your elbows on hard surfaces.
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Use an Optical pick-up mouse.
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Rest your eyes occasionally by focusing on
distant objects.
Writer’s Cramp
Diseases of Scribes and Notaries
“Incessant driving of the pen over paper causes intense fatigue
of the hand and the whole arm because of the continuous and
almost tonic strain on the muscles and tendons, which in
course of time results in failure in the right hand.”
“Those who suffer most from these ailments are book-keepers
and accountants, as they are called, for example those who
hire themselves to work for merchants. Also we must reckon in
the same category the private secretaries of princes.”
“In winter they must take care not to let the hands grow numb
from excessive cold, so they must be protected by good thick
gloves.”
1713: Ramazzini: De Morbis Artificum Diatriba
Writer’s Cramp- Sir Richard Gower
1893
“The occurrence of the disease is influenced less by the
amount than by the manner of writing.
There are in writing two chief elements: the way in which the
pen is held, and the way in which the movements are
effected.”
Writer’s Cramp- Sir Richard Gower
1893
He finds that he is grasping the pen too tightly, and
cannot help doing so; taking a firmer hold seems to
increase the difficulty, and he finds that he writes slowly,
as if a weight were attached to the hand.
The hand feels strangely tired, and an aching pain in the
finger or thumb or first metacarpal bone, or in the wrist or
forearm, makes it still more difficult for him to go on
writing.
Writer’s Cramp- Sir Richard Gower
1893
Gowers recognised that lawyer’s clerks are especially affected by
reason of their cramped position. He described four methods of
writing:
(1)
The hand resting on the little finger; movement of the pen by
the fingers and the thumb.
(2)
The hand resting on the wrist; lateral movement assisted by
the abductors of the wrist.
(3)
The middle of the forearm used as a fulcrum.
(4)
The arm moved freely from the shoulder; the fingers
scarcely move.
He found that cramp occurred especially in the first two groups;
writers using the last method are immune.
Writer’s Cramp- Sir Richard Gower
1893
The best and only free method is to write from the upper arm and
shoulder, with no fixation of the arm; the forearm, wrist and little finger
rest on the table so as to take some of the weight of the limb from the
shoulder-muscles, but both wrist and forearm move along the table as
the writing progresses from left to right.
In this way the pen can be held lightly; very little of the movement is
effected by the small muscles of the hand; the fingers scarcely alter
their position, except when a stroke is carried far above or below the
line; and even for this a movement of the fingers is not always
necessary.
Summary – Computers & Writing
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Ensure desk surface at correct height – adjust
chair if necessary
Use mouse correctly – optical pick-up
Don’t grip pen too tightly
Don’t use a thin pen
Don’t hold a fixed posture – avoid hovering
Take time to stretch when away from the desk
Summary - Sitting
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Choose your seat carefully and adjust to suit
Don’t slump
Don’t cross your legs or ankles
Don’t adopt fixed postures
Take time to stretch when away from the desk
Northern Ireland Civil Service
Occupational Health Service
NICS Centre for Workplace Health Improvement
Lincoln Building
27-45 Great Victoria Street
Belfast BT2 7SH
Website: www.nicsohs.gov.uk