CASE STUDY
Ergonomics Case Study: Preventing a $28,000 Shoulder Injury with a $3,500 Ergonomic Intervention
How a targeted ergonomic risk assessment traced repeated shoulder strains back to a single misspecified part, eliminated the excessive force exposure at its source, and reduced injury risk on the task for good.
$28K+
Median Shoulder WMSD Claim
Median cost of a compensable shoulder WMSD claim
$3,500
Total Intervention Cost
All-in cost to resolve the root cause
~8x
Estimated ROI
Based on the avoided injury cost
CASE OVERVIEW
Findings from Our Ergonomics Case Study: Shoulder Injury Prevention
Situation
A manufacturing client experienced repeated shoulder strain incidents during routine maintenance, specifically the manual removal of a filter cap. Workers reported excessive effort and awkward body positioning as the primary contributors to discomfort and injury.
Analysis
An ergonomic risk assessment by Examinetics identified excessive force requirements and poor mechanical positioning. Further investigation revealed incorrectly sized O-rings that caused workers to over-tighten filter bolts beyond specification. This compounded the force required during removal.
Outcome
A targeted $3,500 intervention eliminated the root cause, restored proper torque specifications, and substantially reduced injury risk on the task. Results led to the ongoing prevention of potential exposure to $28,000+ shoulder WMSD claims.
Key Findings at a Glance
- Excessive Torque: Workers applied 60–155 lbs instead of the 50 lb specification
- Root Cause: Wrong-sized O-rings driving over-tightening behavior
- Compounding Factors: Reach distance, awkward working heights, single-arm force
- Resolution: Engineering controls plus postural and process improvements
CONTEXT & COST EXPOSURE
Why Shoulder WMSDs Are So Costly in Manufacturing
Shoulder work-related musculoskeletal disorders (WMSDs) are among the most financially and operationally disruptive workplace injuries in manufacturing environments. The cost burden extends well beyond the initial medical claim.
An Examinetics client began seeing repeated shoulder strain incidents on a routine filter cap removal task. Workers reported that the task took significant physical effort and put them in uncomfortable positions.
Leadership recognized the pattern and initiated a structured ergonomic evaluation to find the underlying cause before more injuries occurred.
Common Ergonomic Risk Factors for Shoulder Injuries
High-Force Tasks
Repetitive Motion
Awkward Postures
Poor Leverage
RISK FACTOR ASSESSMENT
The Ergonomic Challenge: Six Ergonomic Hazards on One Task
The ergonomic assessment identified six distinct risk exposures during the filter cap removal task. Each factor independently raised the risk of shoulder strain. Together, they created conditions highly conducive to musculoskeletal injury.
1
Excessive Force Requirements
Workers applied 60 to 155 lbs of torque to loosen bolts, exceeding the 50 lb recommended specification by up to three times in some cases.
2
Over-Tightening Beyond Specification
Bolt tightening during filter changes routinely exceeded the 50 lb specification, compounding the effort required during the next removal.
3
Extended Reach Distance
Employees reached 20 to 25 inches because of equipment placement and repurposed containers stored near the workspace.
4
Awkward Working Heights
The task occurred at heights of roughly 33, 52, and 64 inches. None of them aligned with optimal biomechanical positioning.
5
Single-Arm Force Application
Tool size and tight workspace conditions forced workers to apply force with one arm, elbow fully extended. This position eliminates mechanical advantage.
6
Workplace Constraints
A repurposed step stool holding a bucket reduced available workspace, increasing reach distance and limiting safe body positioning.
PHYSICAL STRAIN MECHANISM
Biomechanical Risk Analysis: How Poor Body Mechanics Concentrated Load on the Shoulder
The Strain Pathway
Reach distance, working height, and single-arm force application combined to concentrate load on the smallest and most vulnerable muscles of the shoulder complex.
Arm Positioned at Shoulder Height
Scapular stabilizers are placed under full stretch with reduced load-bearing capacity.
Elbow Fully Extended
Mechanical leverage is reduced to near zero. The shoulder absorbs the primary force load.
Legs and Torso Disengaged
Larger muscle groups are not recruited, so smaller shoulder muscles compensate.
Instability Behavior Observed
Workers stepped on nearby pipes to gain leverage, increasing both fall risk and strain risk.
Why This Posture Carries a High Risk of Injury
When force is applied with the arm raised and the elbow locked, the rotator cuff and deltoid have to stabilize the joint and generate torque at the same time. That dual demand, under load at end-range, is a primary mechanism of rotator cuff tears and shoulder impingement.
Because the legs and core could not be engaged, 100% of the required force was channeled through the shoulder rather than distributed across the kinetic chain.
Workers frequently struggled to loosen the bolts. In some cases, they stepped on nearby pipes to generate additional leverage, which compounded instability and fall risk.
PARTICIPATORY ERGONOMICS PROCESS
Root Cause Discovery: Employee Feedback Surfaced a Process Failure
A participatory ergonomics investigation brought employees, supervisors, and safety personnel into the analysis. The goal was to evaluate the task from multiple perspectives. That cross-functional approach surfaced a root cause that a purely observational assessment would likely have missed.
Root Cause Identified
The O-rings installed on the filters were the incorrect size. This was a process and equipment issue, not a worker behavior issue.
Downstream Effects
- Filters leaked or overflowed because of a poor seal.
- Workers tightened lids beyond the 50 lb specification to stop the leaks.
- Excessive force was then required at the next maintenance cycle to reopen the filters.
Contributing Equipment Factors
Residue Buildup
Hardened residue accumulated on nuts and bolts, increasing friction during removal.
Thread Damage
Repeated over-tightening stripped or damaged bolt threads over time.
Increased Friction
Buildup and thread damage together compounded the force needed for removal.
Key Takeaway: The excessive force requirement was driven by process and equipment failures, not worker technique.
HIERARCHY OF CONTROLS APPLIED
Ergonomic Solutions: Control Measures Applied
The intervention followed the hierarchy of controls framework, prioritizing engineering solutions that remove the hazard at its source before relying on administrative or behavioral measures.
The goal of this comprehensive approach is to immediately reduce hazards and ensure long-term worker safety.
Engineering Controls
The most important step was identifying and sourcing the correct O-ring size. Correctly specified O-rings were procured from certified suppliers and installed across all affected units.
As part of quality verification, post-installation pressure testing confirmed a leak-free seal. The replacement O-rings have an expected lifespan aligned with normal operating conditions.
Engineering control solutions include:
- Purchase and install correctly sized O-rings.
- Restore the proper torque specification to 50 lbs, as originally designed.
- Remove the need for excessive tightening at the source to prevent future equipment damage.
Administrative Controls & Ergonomic Training
Detailed Standard Operating Procedures (SOPs) were updated to require an O-ring inspection at every filter change. This includes visual checks for wear, cracks, or deformation. All maintenance personnel receive quarterly training on the updated SOPs.
Preventive action items include:
- Add the O-ring inspection step to the filter change SOP documentation.
- Provide physical examples of worn or damaged O-rings for early identification and comparison.
- Record every inspection and replacement in a single system of record.
Postural Training & Proper Body Mechanics
A comprehensive training program instructs workers on proper body mechanics for tasks that require force. Reinforcement training sessions are held biannually and integrated into daily safety briefings.
Key postural and body positions include:
- Staggered stance with a slight knee bend: Distributes body weight and lowers the center of gravity, engaging leg muscles to generate power and reduce strain on the back
- Neutral spine maintained throughout the task: Keeps the spinal column in its natural alignment, minimizing shear force and vertebral disc compression
- Force generated through the legs and ground: Uses the stronger muscles of the lower body instead of relying on upper body strength alone
- Elbows slightly bent (never locked): Allows dynamic movement and shock absorption, protecting joints and tendons from hyperextension injuries
Additional Safety Measures
Proper Tool Usage
Torque wrenches (and all other tools) are calibrated on schedule and used to manufacturer specifications, which prevents both over-tightening and under-tightening.
Optimized Workspace Setup
Implementing 5S principles (Sort, Set in Order, Shine, Standardize, Sustain) leads to a safer, more efficient work environment. Organized tools and clear pathways reduce reach distance, minimize the risk of accidents, and improve workflow.
SUSTAINING THE RESULTS
Continuous Improvement: Keeping the Ergonomic Gains In Place
Engineering controls fix the workplace hazard once. A routine cadence of inspection, training, and data review is what keeps it fixed. Here’s a look at how these ergonomic practices should be implemented:
Monthly | Inspection of critical equipment, with all findings recorded in a digital logbook for trend analysis and accountability. |
Quarterly | Training for all maintenance personnel, focused on the updated SOPs. |
Twice a Year | Reinforcement training on proper body mechanics for force-intensive tasks. |
Daily | Correct postural reminders integrated into existing safety briefings. |
RETURN ON INVESTMENT
Financial Impact and Injury Costs Avoided
$28K+
Injury Claim Avoided
Median compensable shoulder WMSD cost per incident
$3,500
Intervention Cost
Total all-in investment to resolve the root cause
~8x
Estimated ROI
Estimated return based on avoided injury cost
Additional Financial and Operational Benefits
Reduced Lost Work Time
Avoiding significant lost productivity and operational disruption.
Lower Workers’ Compensation Exposure
Fewer workers’ comp claims and premiums.
Less Production Disruption
Maintenance tasks completed without incident or delay.
Improved Workforce Morale
Visible safety investment supports retention and engagement.
ORGANIZATIONAL LESSON
Strategic Takeaway: Ergonomic Principles That Transfer to Any Facility
Ergonomic risk often originates from system design failures, not worker behavior. Effective intervention means investigating upstream causes.
What first looked like a posture problem was entirely attributable to incorrect component sizing, equipment condition, and workspace configuration. Workers were adapting rationally to a flawed system.
What a Proactive Assessment Enables
- Eliminate Excessive Force Exposure: Address the hazard at its source instead of managing symptoms.
- Prevent Future Injuries: Break the cycle before additional claims accumulate.
- Improve Operational Efficiency: Equipment that works as designed reduces maintenance time and rework.
Key Principle
When workers are consistently struggling with a task, the first question should not be:
“How do we train them better?”
Instead, it should be:
“What is the system requiring them to do, and why?”
Request an Ergonomic Risk Assessment With Examinetics Today
Examinetics’ certified ergonomic assessment specialists can evaluate the physical demands of the work your people actually do, then recommend control measures that fit your environment and your budget. Assessments are available across single sites and multi-site operations nationwide.
For questions about our workplace ergonomic testing or to request a quote, contact us today.
Ergonomic Risk Assessment FAQs
An ergonomic risk assessment breaks a job down into its physical tasks and measures the demand each one places on the body. A certified ergonomic assessment specialist evaluates force, repetition, duration, posture, and reach. They then compare those physical demands against the physical capabilities of the workers performing the task.
In this case, the assessment measured three things: applied torque, reach distance, and working height. This helped pinpoint where injury risk was concentrated.
The four most common ergonomic risk factors for shoulder injuries include:
- High-force tasks
- Repetitive motions
- Awkward postures
- Poor mechanical leverage
Work performed at or above shoulder height is a major concern because it loads the rotator cuff and deltoid near the end of their range. Risk becomes even greater when several ergonomic hazards appear together on the same task.
It is a framework that ranks control measures by the extent to which they remove a hazard.
Elimination and engineering controls come first because they remove the hazard at its source.
Administrative and work practice controls, such as SOPs and ergonomic training, come next.
Personal protective equipment comes last because it depends on the worker rather than on changing the work.
This case study’s intervention led with engineering controls and used administrative and training measures to sustain them..
Training changes how a worker approaches a task. Engineering controls change the task itself.
No amount of training on proper body mechanics would have reduced the 60 to 155 lbs of torque these workers had to apply, because the excessive force came from an incorrectly sized component (O-ring).
Correcting the part removed the hazard. Training was then reinforced safe-technique for the standard physical demands that remained.
An observational assessment records what an evaluator can see. Participatory ergonomics brings employees, supervisors, and safety personnel into the analysis, which matters because workers know why they adapt the way they do.
Here, employee feedback led directly to the O-ring finding that explained the over-tightening. An observational review on its own would most likely have recorded the posture and recommended training as the solution.
Yes. Examinetics ergonomists work across multi-site and multi-region operations using one standardized set of protocols, so findings at a plant in one state are directly comparable to findings at another location. Program development, gap assessments, and ongoing metrics review can all be managed in one place.