CIEE Repetitive Motion & CTD Prevention 5 — Questions and Answers
Question 1: Which nerve conduction study finding confirms median nerve dysfunction at the carpal tunnel in a worker with suspected CTS?
- Increased H-reflex latency in the lower extremity
- Prolonged distal sensory or motor latency across the wrist (Correct answer)
- Reduced F-wave amplitude in the ulnar nerve
- Elevated compound muscle action potential in the thenar eminence
Correct answer: Prolonged distal sensory or motor latency across the wrist
Electrodiagnostic CTS confirmation requires prolonged distal sensory and/or motor latency of the median nerve across the wrist, reflecting slowed conduction through the compressed carpal tunnel.
Question 2: A company implements a symptom surveillance program as part of its CTD prevention strategy. The PRIMARY purpose of early symptom reporting is to:
- Document cases for OSHA 300 log compliance only
- Identify emerging CTDs before they progress to irreversible structural damage (Correct answer)
- Justify workers' compensation cost forecasting
- Establish baseline data for litigation defense
Correct answer: Identify emerging CTDs before they progress to irreversible structural damage
Early symptom surveillance catches CTDs at reversible stages, allowing timely ergonomic intervention before chronic structural changes such as tendon fibrosis or nerve demyelination occur.
Question 3: The ISO 11228-3 standard provides guidance for ergonomic assessment of:
- Manual lifting and carrying of loads
- Pushing and pulling tasks with wheeled equipment
- Handling of low loads at high frequency (repetitive tasks) (Correct answer)
- Whole-body vibration in seated operators
Correct answer: Handling of low loads at high frequency (repetitive tasks)
ISO 11228-3 specifically covers ergonomic recommendations for handling low loads at high frequency, directly addressing repetitive motion risk in assembly and manufacturing jobs.
Question 4: A new power screwdriver has a no-load speed of 1,200 RPM and produces significant torque reaction. Which handle design feature BEST prevents the torque reaction from producing repetitive wrist injury?
- Textured rubber grip surface
- Reaction bar or torque arm to absorb reactive force (Correct answer)
- Longer handle for increased leverage
- Reduced battery voltage to lower torque output
Correct answer: Reaction bar or torque arm to absorb reactive force
A torque reaction bar or fixture-mounted torque arm absorbs the torque reaction at the tool mounting point rather than transmitting it through the operator's wrist.
Question 5: Which psychosocial work factor has been shown in research to INCREASE susceptibility to upper-extremity CTDs independent of physical loading?
- High job autonomy and decision-making latitude
- High job demands combined with low control (job strain) (Correct answer)
- Positive supervisor feedback frequency
- Adequate task variety within a shift
Correct answer: High job demands combined with low control (job strain)
Job strain (high demands + low control) is associated with elevated musculoskeletal disorder risk through both physiological stress pathways and reduced ability to modify work pace or technique.
Question 6: When quantifying repetition for CTD risk assessment, which approach most accurately reflects tissue exposure compared to simply counting cycles per minute?
- Measuring ambient temperature at the workstation
- Recording time-weighted average (TWA) exposure across the full shift (Correct answer)
- Counting the number of distinct product types handled
- Surveying worker perception of workload difficulty
Correct answer: Recording time-weighted average (TWA) exposure across the full shift
Time-weighted average exposure integrated over the full shift accounts for variation in task pace and duration, providing a more accurate picture of cumulative tissue loading than instantaneous cycle counts.
Question 7: After implementing ergonomic controls for a repetitive packaging line, which metric would BEST evaluate the EFFECTIVENESS of the intervention in reducing CTD risk?
- Employee satisfaction survey scores
- Pre- and post-intervention peak force measurements and OSHA recordable CTD incidence rates (Correct answer)
- Production throughput per hour before and after redesign
- Number of ergonomic awareness training sessions completed
Correct answer: Pre- and post-intervention peak force measurements and OSHA recordable CTD incidence rates
Combining objective biomechanical measures (peak force) with health outcome data (OSHA recordable CTD rates) provides the most direct evidence of whether the intervention reduced both exposure and injury.
CIEE Repetitive Motion & CTD Prevention 5
Which nerve conduction study finding confirms median nerve dysfunction at the carpal tunnel in a worker with suspected CTS?