Ergonomics WRULD and musculoskeletal disorders Loisa Sessman, Halmstad University

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

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

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

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

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

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

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

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

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

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

Epicondylitis Lateral epicondylitis – De Quervain's disease (tennis elbow) Injuries and pain resulting from work with computer mouse Causes of high repetitive finger movements in combination with static work The symptoms: pain in the forearm and weakness in the hand and wrist Medial epicondylitis – golfer’s arm Similar to tennis elbow Affects the medial epicondyle of the humerus Muscle Tendon Medial epicondylitis Lateral epicondylitis Loisa Sessman, Halmstad University

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

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

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

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

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

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