International Module W 506 Ergonomic Essentials Day 3

International Module W 506 Ergonomic Essentials Day 3

MUSCULOSKELETAL DISORDERS (MSDs)

Outline • MSDs – – – Definition Parts of body at risk Impact of MSDs on industry Risk factors Low back disorders Risk management • WRULD – – Definition Risk Factors Injury mechanisms Risk management

Nature & Causes of Manual Handling Disorders • 4 key physical risk factors: – – – Repetition Force Posture Vibration Combination of factors • Cumulative damage

Low Back Disorders • The spine – Function • Facilitates movement • Protects spinal cord • Protects vital body organs

Low Back Disorders • Structures of the spine – Muscles, tendons and ligaments – Vertebrae – Discs Mc. Phee

Low Back Disorders • Injury Mechanisms of the Spine – – – Lifting/forceful movement Awkward postures Heavy physical work Whole body vibration Personal variables (strength, age, gender, abdominal girth HOW?

Risk Identification • Indicators for risk in manual handling tasks: – – – Weight & load (force) Frequency of lift (repetition) Distances moved (force, posture) Workplace layout (posture, vibration) Personal variables (abdominal girth, age, gender, strength and mobility)

Risk Assessment Strategies • Review work tasks to identify ‘risky’ tasks/personnel – Physical demands – Psychological demands – Individual risk factors • Undertake formal manual task risk assessment – Legislative requirement to use specific tool? • MAC (UK) • COP Risk Assessment Tool (Australia) • OCRA (EU standard)

Detailed Ergonomics Methods • Biomechanical – ‘risk’ at max. compression force of 3. 4 k. N at L 4/L 5 or L 5/S 1 joints • Physiological – ‘risk’ at max. energy expenditure of 2. 2 – 4. 7 kcal/min • Psychophysical – ‘risk’ at max. acceptable weight (75% female & ~ 90% male workers) • Combination Approach

Examples of these ergonomics methods (1) • Biomechanical – 2 D & 3 D static strength models – Lumbar Motion Monitor Source: http: //www. nexgenergo. com/ergonomics/lumbarmm. html

Examples of these ergonomics methods (2) • Physiological – HR monitoring – Borg rating of perceived exertion scale (RPE) Borg’s RPE (15 level scale) • • • • 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 No exertion at all Extremely light Very light Light Somewhat hard Hard Very hard Extremely hard Maximal exertion

Examples of these ergonomics methods (3) • Psychophysical Methods – Snook Tables • Designing manual tasks for more than 75% female work population reduces risk of injury • Tables provide information on object weight, distances load is lifted from and to, and frequency of lift. • Useful for running ‘what if’ scenarios. • Useful web link: http: //libertymmhtables. libertymutual. com/CM_LMTables. Web/pdf/Liberty. Mutual. Tables. pdf

Examples of these ergonomics methods (4) • Combination Approach – NIOSH equation • Biomechanical, physiological, psychological criteria to determine lifting limits • 3 indices: – lifting index » Ratio of load to recommended weight limit – Job severity index » Measurement of job demands – Lifting strength rating » Strength requirements

Other Ergonomics Methods (1) • Epidemiological – Nordic Questionnaire

Other Ergonomics Methods (2) • Postural methods – – OWAS RULA REBA • Combination postural methods – QEC – Man. TRA UOW

Risk Control 1. Eliminate manual handling activity 2. Redesign to eliminate risk 3. Reduce the risk 1. Redesign load 2. Redesign work area 3. Use mechanical aids &/or equipment 4. Training in risk assessment and ergonomic principles

Example of Workplace Modification • This workplace washes hospital linen. • Linen bags are suspended on a conveyor system and delivered to worker who unties the bottom of the bag and directs washing into chute, eliminating need to manually handle the bag. UOW

Use of mechanical aids • Use of bin lifter to assist with emptying large and or heavy bins. Backwatch collections Work. Cover NSW

Principles of manual handling • Commit to risk management approach (eliminate manual handling risk!) • When lifting & handling a load – – – – – Plan the lift/handling activity Keep the load close to waist (centre of gravity) Keep stable position Ensure good grip ‘good posture’ (head up, keep the curves 0 Avoid twisting/sideways bending Move smoothly Know your capacity Adjust the load position AFTER putting it down – e. g. sliding

General Guidance for Lifting & Handling Source: HSE: Getting to Grips with Manual Handling

Lifting & Lowering Mass Guidance Source: HSE: Getting to Grips with Manual Handling

WORK-RELATED UPPER LIMB DISORDERS (WRULDs) • • • CTD RSI OCD OOS WRULD! BP

WORK-RELATED UPPER LIMB DISORDERS (WRULDs) • Increasing occurrence of WRULDs • Risk Factors: Physical Risk Factors Psychosocial Risk Factors Individual Risk Factors Repetition Job demands Age Force Job control Gender Posture Social relations at work Socioeconomic status Vibration Pre-existing musculoskeletal disorders

The Upper Limb (1) • • • Shoulder Upper arm Forearm Wrist Hand BP

The Upper Limb (2) • Function of the arm and hand – Mechanical power (large muscles) – Manipulation (small muscles of hand) BP

Types of grip • Pinch/Precision • Power/Palmar Mc. Phee

UL: Injury Mechanisms (1) • Shoulder – – High moments at shoulder Static load on shoulder Awkward shoulder posture No time for tissue recovery BP

UL: Injury Mechanisms (2) • Hand & Forearm – – – High forces + repetitive work High forces required by task Non-optimal postures Static loads Use of power tools • High vibration • High/poor torques – High levels of precision placement in task • Increases time • Increases static loading • Increases force requirements

WRULD: Risk Identification • Risk Identification – – – – Force (weight and load) Repetition (frequency of activity) Posture (workplace layout: distances, forces) Duration Psychosocial factors Work organisational factors (e. g. shift work) Personal variables (e. g. age, gender)

WRULD: Risk Assessment • Risk Assessment Techniques – Simple • e. g. HSE risk Assessment Worksheet – Complex • e. g. RULA, OWAS, OCRA (ISO 11228 -3: 2007)

WRULD: Risk Control (1) • Risk Control – Structural modifications • Use of ‘ergonomic’ work tools – Bend tool handles to 5 o-10 o – Avoid extreme ulnar/radial deviation – Use low forces when rotating or flexing wrist – Minimise forces for finger pinch movements (<10 N (20% of weakest operator max. pinch strength)) Stevenson ASCC 2007

WRULD: Risk Control (2) • Risk Control – Structural modifications (cont. ) • Appropriate workstation layout & equipment – Facilitates optimal postures • Reduce excessive force, awkward postures and any compression of tissues while working – Use large muscle groups, not small Stevenson

WRULD: Risk Control (3) • Organisational modifications – ‘Ergonomically’ designed job (pace, variation, etc) • • Rotate between high and low repetition jobs Use machinery for repetitive jobs and workers for variable tasks Allow self pacing Utilise ergonomic criteria in planning work systems and purchasing equipment – Reduce duration of frequent & repetitive movements • Design out repetitive tasks/jobs (esp. < 30 second cycle time) – Ensure adequate recovery time • Eliminate unnecessary overtime • Avoid repetitive work in extreme tempts. • Pauses in work cycles • Training & Retraining

Summary • MSDs – – – Definition Parts of body at risk Impact of MSDs on industry Risk factors Low back disorders Risk management • WRULD – – Definition Risk Factors Injury mechanisms Risk management