CEA Musculoskeletal Disorder Prevention 3 — Questions and Answers
Question 1: Which factor is NOT included as a multiplier in the Revised NIOSH Lifting Equation (RNLE)?
- Load Constant (LC)
- Coupling Multiplier (CM)
- Vertical Travel Distance Multiplier (DM)
- Worker Age Multiplier (WAM) (Correct answer)
Correct answer: Worker Age Multiplier (WAM)
The RNLE includes multipliers for horizontal distance, vertical height, distance traveled, asymmetry, frequency, and coupling quality — but NOT worker age.
Question 2: A data entry clerk develops pain and stiffness in the neck and upper trapezius after several months on a new workstation. The MOST likely ergonomic root cause is:
- Insufficient keyboard wrist rest thickness
- Monitor positioned too low requiring sustained neck flexion (Correct answer)
- Chair seat pan too long causing pressure behind the knees
- Keyboard tray positioned too low
Correct answer: Monitor positioned too low requiring sustained neck flexion
A monitor positioned too low forces sustained neck flexion, increasing static loading on cervical muscles and the upper trapezius, leading to neck and shoulder MSDs.
Question 3: What is the primary biomechanical reason that grip force increases MSD risk at the wrist and forearm?
- Gripping reduces blood flow to the fingertips only
- High grip force increases tendon tension and compressive forces on wrist structures (Correct answer)
- Grip activates the triceps, overloading the elbow
- Grip force directly compresses the ulnar nerve at the wrist
Correct answer: High grip force increases tendon tension and compressive forces on wrist structures
Forceful gripping increases tension in finger flexor tendons that pass through the carpal tunnel and elevates compressive forces on wrist joints, raising MSD risk.
Question 4: Which of the following describes 'cumulative trauma disorder (CTD)' most accurately?
- A single traumatic event that damages musculoskeletal tissue
- A condition caused by the accumulation of micro-traumas from repeated occupational exposures over time (Correct answer)
- An acute injury resulting from one excessive lift
- Any musculoskeletal disorder with a duration exceeding 90 days
Correct answer: A condition caused by the accumulation of micro-traumas from repeated occupational exposures over time
CTDs develop gradually from repeated sub-threshold exposures that cause micro-damage faster than tissue can repair, eventually manifesting as clinically significant disorders.
Question 5: A production line requires workers to assemble small components with a pinch grip 800 times per hour. Which engineering control would BEST reduce MSD risk?
- Providing anti-fatigue mats at the workstation
- Redesigning the components or fixtures to allow a power grip instead of a pinch grip (Correct answer)
- Requiring workers to take two 10-minute rest breaks per shift
- Adding wrist supports to the workbench edge
Correct answer: Redesigning the components or fixtures to allow a power grip instead of a pinch grip
Pinch grip generates up to 5 times more tendon and joint force than a power grip for equivalent effort; redesigning to allow a power grip is the most effective engineering solution.
Question 6: When evaluating awkward postures using the RULA (Rapid Upper Limb Assessment) tool, a score of 7 indicates:
- Acceptable posture; no change required
- Further investigation may be required soon
- Investigate and implement changes
- Investigate and implement changes immediately (Correct answer)
Correct answer: Investigate and implement changes immediately
In RULA, a grand score of 7 represents the highest action level, indicating unacceptable risk that requires immediate investigation and implementation of changes.
Question 7: Which condition involves inflammation of the tendon sheath and is characterized by a 'trigger' or locking sensation in the finger?
- Carpal tunnel syndrome
- Stenosing tenosynovitis (trigger finger) (Correct answer)
- De Quervain's tenosynovitis
- Dupuytren's contracture
Correct answer: Stenosing tenosynovitis (trigger finger)
Stenosing tenosynovitis (trigger finger) involves thickening of the tendon sheath causing the tendon to catch or lock as it glides, producing the characteristic triggering sensation.
CEA Musculoskeletal Disorder Prevention 3
Which factor is NOT included as a multiplier in the Revised NIOSH Lifting Equation (RNLE)?