1. Ergonomics
WRULD and musculoskeletal disorders
Loisa Sessman, Halmstad University

2. Health and safety
 Accidents
 Unsafe behavior
 Unsafe systems
 Everyday accidents
 Slipping, tripping & falling
 Machinery – safety distance
 Ergonomic injuries
 Lifting and handling injuries
 Work-related upper limb disorders
 Musculoskeletal pain resulting from unsatisfactory
working posture
Loisa Sessman, Halmstad University

3. Ergonomic injuries
 Mismatch
 Over-use injury
 “Creep” effect (fatigue)
 Mechanical strength
 Co-ordination
 Range of motion
 Foreseeable, injuries can be predicted!
 Back pain
 Occupational
 Personal risk factors
Loisa Sessman, Halmstad University

4. Lifting and handling
 Lift close to the body
 Reduce the lever arm
 Control
 Symmetric
 Avoid asymmetric lifting
 Foot placement
 Weight limits
 Different limits for different countries
 Sweden, 7 kg = ok, 7-25 kg = risky 25 kg = very
high risk
Loisa Sessman, Halmstad University

5. Work-related upper limb disorders
 WRULD
 Umbrella term for CTD and RSI
 Repetitive strain injury (RSI)
 Cumulative trauma disorders CTD
 Mainly affects:
 Industrial assembly workers
 Workers at supermarket checkouts
 Musicians
 Keyboard users
Loisa Sessman, Halmstad University

6. RSI & CTD
 Often occurs in the upper limb
 Injuries in nerves, muscles, ligaments, tendons
and joints etc
 Causes pain
 Related to work intensity and duration
 Weeks, months or years
 Diffuse symptoms
 Often unreported
 Several reasons (work and/or leisure time)
Loisa Sessman, Halmstad University

7. RSI & CTD
 CTD & RSI increases
 Increased awareness and reporting
 Increased specialization
 Computer work
 Mental stress
 Posture
 Force
 Repetition
Loisa Sessman, Halmstad University

8. Postures
 Extreme flexion and extension, ulnar and radial
deviation of the hand
 Carpal Tunnel Syndrome
 Tenosynovitis
 Extreme flexion of the elbow
 Cubital Tunnel Syndrome
 Extreme rotation of the forearm
 Epicondylitis
 Work above shoulder level
 Thoracic Outlet Syndrome
Loisa Sessman, Halmstad University

9. Carpal Tunnel Syndrome
 Results from high repetitive work in extreme
positions, often in combinations with force
 Median nerve get squeezed
 Numbness, tingling pain and clumsiness
Loisa Sessman, Halmstad University

10. Tenosynovitis
 Tendon sheath swells
 Occurs at wrists and ankles where tendons cross
ligaments
 Pain, burning sensation and swelling
Loisa Sessman, Halmstad University

11. Cubital Tunnel Syndrome
 Compression of the ulnar nerve in the elbow
 Tingling and numbness occurs at the little finger
and the ulnar side of the ring finger
 Causes when resting the elbow on a hard surface
or sharp edge
Loisa Sessman, Halmstad University

12. Epicondylitis
 Lateral epicondylitis – De
Quervain's disease (tennis elbow) Lateral epicondylitis
 Injuries and pain resulting from
work with computer mouse
 Causes of high repetitive finger
Medial
movements in combination with epicondylitis
static work Tendon
 The symptoms: pain in the forearm Muscle
and weakness in the hand and
wrist
 Medial epicondylitis – golfer’s arm http://www.orthoactiv.de/index.php?open=peripherenerven
 Similar to tennis elbow
 Affects the medial epicondyle of
the humerus
Loisa Sessman, Halmstad University

13. Tendonitis or tendinitis
 Inflammation of a tendon
 Pain, swelling, burning sensation
 Tendonitis or bursitis at the rotator cuff
 Unnatural static positions
 Heavy work
 External load
 Repetitive arm movements
 Work above shoulder height
Loisa Sessman, Halmstad University

14. Thoracic outlet syndrome
 Compression of three nerves of the arm and blood
vessels
 Numbness
 Difficult to move the arm
Loisa Sessman, Halmstad University

15. Contact stress
 Mechanical stress (contact stress) on nerves and
tendons
 Handhold objects with sharp edges and hard objects
 Vibrating tools - Raynauds syndrom (white fingers)
 Reducing contact stress
 Change posture
 Use gloves
 Use design-friendly tools
 Use grip surfaces that are smooth, non conductive
of cold or heat and anti-slip
Loisa Sessman, Halmstad University

16. Repetition
 High repetitive work require more muscle effort
 The muscles need more time to recover
 Vary postures can reduce repetitive movements
Loisa Sessman, Halmstad University

17. Other causes
 Temperature
 Cold
• Blood circulation
• Time for recovery
 Heat
• Sweat – slip
 Vibration
 Blood circulation
 Require greater grip force
 Try to isolate the vibrations!
Loisa Sessman, Halmstad University

18. Conclusion
There are several musculoskeletal disorders caused
by extreme postures, forces, high repetitive work.
Also hand-tools and environmenment
can cause injuries.
Loisa Sessman, Halmstad University