Occupational Ergonomics

Intro to Ergonomics - Work Fit Fundamentals

• Ergonomics: "Fitting the job to the worker." Goal: optimize human well-being & system performance.
• Primary Goals:
  • Enhance performance & productivity.
  • Improve safety, reduce injuries/errors.
  • Increase comfort & job satisfaction.
• Types:
  • Physical: Body mechanics, posture, repetitive tasks, workplace layout.
  • Cognitive: Mental workload, decision-making, human-computer interaction.
  • Organizational: Teamwork, work design, communication, organizational culture.
• Importance:
  • Prevents Musculoskeletal Disorders (MSDs).
  • ↑ Productivity, ↓ errors & costs.

⭐ The primary goal of ergonomics is to enhance efficiency and well-being by adapting work conditions to suit the capabilities of the worker.

Ergonomic Risk Factors - Strain Triggers

Key physical factors increasing Musculoskeletal Disorder (MSD) risk. 📌 Mnemonic: R.A.F.T.S.

• Repetition: Performing the same motions frequently or for prolonged periods.
• Awkward Postures: Deviating from neutral body positions.
  • Neck flexion > 20°
  • Shoulder flexion/abduction > 60°
  • Wrist deviation (ulnar/radial)
  • Sustained trunk flexion or twisting.
• Force: Amount of physical effort required; can be high or sudden.
• Time (Static Postures): Holding a posture for a long duration, leading to muscle fatigue.
• Stress (Contact Stress): Localized pressure from hard surfaces or sharp edges on body parts (e.g., wrists, forearms).

• Other Physical Factors:
  • Vibration: Hand-Arm Vibration (HAVS) from power tools; Whole-Body Vibration (WBV) from driving.
  • Extreme Temperatures: Working in excessive heat or cold.
• Psychosocial Factors: (Briefly)
  • High job demands, low job control, poor workplace support.

⭐ The most common combination of risk factors leading to MSDs is repetition combined with force and/or awkward posture.

Common Ergo Disorders - Workplace Ailments

Common Work-related Musculoskeletal Disorders (WMSDs):

• Upper Limb:
  • Carpal Tunnel Syndrome (CTS): Median nerve compression at wrist.
    • Symptoms: Paresthesia (thumb, index, middle, radial ring finger), nocturnal pain.
    • Signs: Tinel's and Phalen's tests have limited diagnostic accuracy; modern diagnosis relies on clinical history, electrodiagnostic studies (nerve conduction/EMG), and imaging.
  • Tendinitis/Tenosynovitis: Inflammation of tendon/sheath.
    • Examples: De Quervain's (thumb), rotator cuff (shoulder), trigger finger.
  • Epicondylitis:
    • Lateral (Tennis Elbow): Pain at outer elbow.
    • Medial (Golfer's Elbow): Pain at inner elbow.
  • Hand-Arm Vibration Syndrome (HAVS): From vibrating tools; vascular (white finger), neuro, musculoskeletal effects.
• Back:
  • Low Back Pain (LBP): Most common WMSD; often non-specific.
  • Disc Herniation: Nucleus pulposus protrusion, potential nerve root compression.
• Neck:
  • Cervicalgia: General neck pain and stiffness.
  • Tension Neck Syndrome: Postural pain/stiffness in neck/shoulders.

⭐ While Phalen's test and Tinel's sign are still used for Carpal Tunnel Syndrome, electrodiagnostic studies provide definitive confirmation and severity assessment.

Prevention & Control - Ergo Solutions

⭐ Engineering controls are the most effective in the hierarchy for ergonomics, aiming to fit the job to the worker.

• Hierarchy of Controls: Prioritizes interventions. 📌 E.S.E.A.P. (Elimination, Substitution, Engineering, Administrative, PPE).

• Engineering Controls: Modify tasks, workstation, equipment.

  • Workstation: Adjustable chair/desk height, monitor position (top at/below eye level).
  • Tools: Ergonomic handles, ↓vibration.

• Administrative Controls: Change work procedures/schedules.

  • Job rotation, work-rest cycles, training on proper techniques.

• Personal Protective Equipment (PPE): Last resort.

  • E.g., anti-vibration gloves (note limitations).

• Ergonomic Assessment: Observation, checklists (RULA, REBA), direct measurement.

High‑Yield Points - ⚡ Biggest Takeaways

• Occupational Ergonomics: Adapting work to the worker to prevent Musculoskeletal Disorders (MSDs).
• Common MSDs: Carpal Tunnel Syndrome (CTS), Low Back Pain (LBP), Tendinitis, Tenosynovitis.
• Major risk factors: Repetitive tasks, awkward postures, forceful exertions, vibration.
• Prevention hierarchy: Engineering controls (e.g., tool redesign) are most effective, followed by administrative controls.
• Ergonomic assessment tools include RULA (Rapid Upper Limb Assessment) and REBA (Rapid Entire Body Assessment).
• Primary goals: Improve worker comfort, safety, efficiency; reduce work-related injuries.