Work-Related Musculoskeletal Injuries and Prevention

Introduction

Work-Related Musculoskeletal Injury (WRMI) :

"a wide range of inflammatory and degenerative diseases and disorders that result in pain and functional impairment...arise when an individual is exposed to work activities and work conditions that significantly contribute to their development or exacerbation but which do NOT act as the sole determinant of causation"[1]

"[WRMIs] affect the soft tissue of the body, such as the muscles, the tendons that connect muscles to bones, ligaments that connect bone to bone, nerves and blood vessels. These disorders have also been referred to as: cumulative trauma disorders, repetitive strain injuries and overuse injuries."   -SHARP (Safety and Health Assessment and Research Prevention)

Prevalence [1]

Lifetime prevalence = 90%

12 mos Prevalence Prevented from Working Sx Last > 3 days
Low Back            62.5%                   7.8%           38.4%
Neck            47.6%                   3.5%           29.7%
Upper Back            41%                   1.7%           22.9%
Shoulder            22.9%                   1.1%           12.5%



“We tend to think that we are not going to get hurt because we have all this knowledge about on-the-job injuries. Our knowledge or ergonomics might help us avoid injury, but we’re still forced into bad postures, and we’re lifting more than we should.” -Teri Jennings PT, NY, USA, Fosnaught (1999)

Although the incidence is high, reported injury in the workplace is NOT

“…many PTs who are injured don’t go to employee health…they treat themselves, or a colleague treats them, and they keep on working. The injury’s not reported and there’s no cost to management.”-Jones PT quoted from Fosnaught (1999)

"The prevelance of shoulder symptoms seems to be relatively high, varying from 6% to 25% in the general population."[1]

In a Nut Shell, the PT profession requires "high levels of postural stresses (standing, walking, stooping)"[2] repeatedly throughout each day.  

Who’s at risk for developing WRMI?[1][3][4][2]

General Risk Factors

  • Physical therapy.jpg
    Repetitive, labor intensive work
  • Younger (<30)
  • During first 5 yrs or practice
    • >50% (including practicing students) unofficially state sustaining WRMIs, yet do not report these injuries to proper personnel.
  • Lifting pt’s and/or equipment
  • Transferring pt’s
  • Responding to unexpected movement
  • Manual Therapy
  • Failure to take rest breaks
  • Inadequate staffing
  • Inadequate training on injury prevention


Note: Lifting and transferring pt's is the most likely cause of injury secondary to the following contributing factors: awkward shape of a body (i.e. not compact, no handles or easy places to grab), combativeness, contractedness, demented, resistant to movement, fear etc...

Psychosocial Risk Factors  [1][4]

  • Type A personality
  • Low work content
  • Low social support
  • High perceived work load
  • Time pressure
  • Low job control
  • Perceived stress
  • High psychological stresses
  • Providing domestic work
  • Unsatisfactory leisure activities

External Risk Factors

Low Back [1][4][5] [2]

  • Small workspace
  • High productivity demands
  • Understaffing
  • Pt’s size, condition, shape, assisting during gait, confused/agitated
  • Providing manual resistance
  • Unadjustable beds/mats/chairs/commodes
  • Repetitive bending, twisting, lifting
    • Cumulative loads to the spine throughout the day, week, years
    • Although peak forces may be mild, repetitive cumulative loads increase risk of damaging low back tissue thus resulting in injury

Neck/Upper Back/Shoulder [1][4] [6]

  • Type A personality
  • Scheduling
  • Rest breaks
  • Work-load
    • OverTime
    • High work-load
  • Repetitiveness (Female)
  • Manual techniques
  • High mental load
    • Hectic work enviornment
    • Exhaustion at end of day
  • Unsatisfactory leisure time
    • Female and Males - Neck
    • Males - Shoulder
  • Blue collar work (Male)

Hand and Wrist [7]

  • High volume of manual therapy
  • Static positioning of a joint - decreased blood flow to area
  • Sustained duration pressure through a joint
  • Small, unsupported joints
  • High work load
  • Scheduling/decreased rest breaks

Internal Risk Factors

Low Back [1][4][5][2]

  • Female
    • Ht and wt less than male counterparts
    • Pregnancy, increased stresses on body and increased ligamentous laxity
  • Psychosocial Health
    • Stress
  • Lack of experience
    • Uncomfortable requesting assistance
  • Postural Stresses
    • Standing, walking, stooping

Neck/Upper Back/Shoulder[1][4]

Poor-posture-examples.jpg


  • Poor posture "rounded shoulders" - increased anterior muscle girth
  • Volume of pressing is greater than pulling - i.e. weaker posterior musculature
  • Lack of stability through trunk and hips
  • Age
  • Smoking
  • Mental stress
  • Previous injury
  • Unhealthy BMI

Wrist and Hand [8]

  • MCP is more commonly injured in younger therapists
  • CMC is more commonly injured in older therapists
  • Increased CMC joint laxity
  • Decreased tip pinch strength
  • Decreased Body Mass Index (BMI)

Biomechanical Forces Present in High Risk Activities

M vs F.jpg  

Consequences of Injuries [1][9]

Personal 

Depression.jpg



  • Depression
  • Anger
  • Early signs of aging due to stress
  • Potential negative effects on family or relationship


Work-Related

  • Leave work
  • Absentee
  • Worker’s Compensation
  • Lost productivity
  • Retraining of staff

Economical Costs

  • The direct costs of an injury are the easiest to see and understand.  These costs include emergency room and doctor visits, medical bills, medicines, and rehabilitation.
  • Indirect costs of an injury are often overlooked.  These costs can amount up to 4 times the direct cost of the injury.  Indirect costs include administrative time dealing with the injury and medical care, raises in insurance costs, replacing the hours lost of the injured employee with hiring another employee, loss of reputation and confidence in employees and clients, unwanted media attention, and more.
  • The total costs of an injury are suprising.  Beyond the direct costs, the indirect costs greatly increase the overall costs.  This is the true amount that the injury will cost in terms of money.

Prevention of Injuries

Risk Assessment [1]

  • Employer’s responsibility
    • Eliminate or minimize work hazards
    • encourage open discussion among employees regarding injury and prevention
  • To include (but not limited to):
    • Minimal lifting approach
    • Knowledge/training on proper use of equipment
    • Adequate staffing
    • Re-evaluating content and frequency of training courses
      • Especially w/ younger/newly hired PT’s
      • Training programs have little effect without aggressive ergonomic evaluation
    • PT available for staff

Training [5][7]

  • "...bodymechanics and back-care training are valid elements of injury prevention programs, but only when combined with an ergonomic approach..." -Owen and Garg
  • "To help prevent shoulder injuries, employers should conduct a worksite evaluation, consider feasible control measures and train employees"[3]
  • "Integrating your entire body, using your body's weight, proper joint alignment, and a variety of movements will help develop dynamic body mechanics ensuring the successful use of your hands." - Barbara Frye

Custom Training [9]

  • Bio-mechanic and ergonomical training, lifting and manual handling with hand/body as main tool, safe use of equipment, effects sustained postures, caseload variation, work organization, working with other professionals
  • Include Cognitive Behavioral Theory
    • Activity Pacing
      • Scheduling activities
    • Attention Diversion
      • Distracting patient
    • Cognitive Restructuring
      • Identify and restructure dysfunctional thoughts and emotions
    • Goal Setting
      • Patient-centered
    • Graded Exposure
      • Gradual systematic progression
    • Maintenance Strategies
      • Plan to manage flare-ups
    • Problem-solving Strategies
      • Define problem and how you are going to solve the problem
  • Prompted “micro” breaks
    • Leads to increased work productivity
  • However ... risk reducing behaviors without immediate benefit are often NOT perceived as beneficial

Body Mechanics [10] [5][2] [2]

Spinal Compression is a result of trunk extensor activation along with ligaments and discs trying to support the force from Lumbar spine up. According to NIOSH (National Institute for Occupational Safety and Health) spinal compression >3400N puts a person at risk of low back injury; with a maximum permissable limit of 6400N. When comparing 3 different (unspecified) lifting techniques, Gagnon et al. estimated compressive forces to be 5744-7951N at the L5/S1 disc space. This estimate exceeds the limit of risk but also exceeds the permissable limit defined by NIOSH.


Analysis & Evidence shows:

"Free Style" vs "Squat Lift"

  •       Free style lift revealed participants pulled load toward body while a squat lift requires vertical lifting
  •       Free Style lifting limiting muscle is hip extensor strengh
  •       Lifting Vertical limiting muscle is knee extensor strength
  •       Free style lifting (“perceived as most suitable by subject”) vs. Squat lift
  •       Able to lift more weight (~16% greater load) and repetitively 
  •       Transfers load from the UE and torso to the LE (which have greater strength)
  •       Greater load = greater lift angle
  •       The greater the angle leads to less muscle energy expenditure

Lifting at an angle / "free style" results in:

  • Decreased compressive forces at elbow, shoulder, L5/S1 disc space (~11%), and hip
  •       Pt reported comfort and feeling of security during transfer
  • Increased compressive forces at knees and ankles

Green Zone.jpg
Lifting Techniques

  • Keep objects in your “green” zone
    • "Green" zone = elbows at your side
    • Reaching at arm’s length increases load on low back x 10
  • Bend w/ legs NOT (only) hips
    • Bending at "hips only" results in substantial increase of spinal loading; demanding the lumbar muscles and ligaments to support the trunk which is usually ~ 1/2 total body weight[5]
  • Keep normal curves
    • Cervical, Thoracic, Lumbar, and Sacral
  • No holding breath
  • Legs and abdomen
  • Know limits 


  • MAINTAIN NEUTRAL SPINE 
    • Keep normal curves
      • Cervical, Thoracic, Lumbar, and Sacral
  • Keep head up
  • Wide BOS
  •      Scissor position (in tight spaces)
  • Keep load close
  • Contract Abdominals
  • Bend knees and hips
  • Move Trunk (hips up) as a whole body unit --> Move feet (do NOT twist)
     
    Spine.png
Lifting.png










Equipment [3][5]

  • Non-Compliance with assistive devices is generally due to shortage of staff to assist, increased time (of pt care) and accessibility of equipment, apprehension of younger PT's to contradict “typical” protocol of more experienced PTs and ward culture
  • Compliance is greater with heavy patients, and when there is a perceived risk of injury
  •         Compliance increases when staff properly trained on equipment
  • May reduce peak forces however what is the effect on cumulative forces?
    • Bending to retrieve equipment, pt transfers and set-up of equipment
    • Many times results in greater forward flexed times and greater cumulative spinal forces than manual transfer

Hand and Wrist Saving techniques [7]

Good example of reinforcing one hand with the other and using the knuckles instead of the finger tips


  • ALWAYS keep joints that you are not using relaxed
  • Use elbow for sustained, static pressure
  • Use the forearm for effleurage, increasing circulation to the area
  • Knuckles can be used for light to medium weigth bearing
  • Keep joints in line with one another
  • Keep wrist in neutral
  • Two hands are always better than one
  • Reinforce joint in with opposite hand
  • Use entire body in movements

Posture.png
Prevention/Intervention Strategies [1][4]

  • Reporting Injuries
    • Makes the problem less invisibile --> increase workplace safety
  • Implementing mandatory “micro” rest breaks throughout the day
  • Managing/Coping with stress
  • Footwear
  • Use your entire body when possible, especially large muscles that are meant to take the load
  • Exercise
    • Increase core/trunk strength
    • Flexibility
    • Endurance
    • Mid and Lower Trap, Rotator Cuff
  • Warming up prior
    • Stairs, walking ~5 min
    • Stretching/Going through the motions before a transfer/lift/manual therapy
  • Maintain Healthy Weight/Lifestyle
  • Posture Checks throughout day
    • Sitting, standing, pt care
  • Ask for help
    • Work as a team (Co-treats)
  • Use your whole body when performing manual therapy instead of just your upper extremities
  • Use of Assistive Devices (including but not limited to)[9]:
  • Battery operated lifts (hoyer lifts)
  • Gait belts
  • Draw sheets and friction reducing sheets

Exercise to Maintain Healthy Shoulders[3][4]

PottsShoulder.jpg
  • Key to prevention of shoulder injury is strengthening core rotator cuff musculature
  • Apply heat to shoulder muscles before exercise
  • Keep arm below shoulder height while doing arm stretches
  • Gradually increase shoulder movements while warming up

  i.e. - big circles, across body movements, shoulder blade rolls etc.

  • While sitting or standing, keep arm vertical and close to body
  • Pendulum stretching exercises relieve pressure on the rotator cuff
  • Perform muscle strengthening exercises



Exercise Selections for Prevention of Shoulder Injury

Shoulder Injury Prevention Video Clip


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Recent Related Research (from Pubmed)

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References

  1. 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 1.11 The chartered society of physiotherapy. Employment relations and union services:health & safety –work-related strain injuries (musculoskeletal).www.csp.org.uk. Accessed June 2011.
  2. 2.0 2.1 2.2 2.3 2.4 2.5 Garg A, Owen B, Beller D and Banaag. A biomechanical and ergonomic evaluation of patient transferring tasks: bed to wheelchair and wheelchair to bed. Ergonomics. 1991;34 (3). 289-312.
  3. 3.0 3.1 3.2 3.3 Yassi A, Cooper JE, Tate RB, et al. A randomized controlled trial to prevent patient lift and transfer injuries of health care workers. Spine. 2001.;26 (16) 1739-1746.
  4. 4.0 4.1 4.2 4.3 4.4 4.5 4.6 4.7 Fredriksson K, Alfredson L, Koster M , et al. Risk factors for neck and upper limb disorders: results from 24 years of follow up. Occup Enviorn Med. 1999;56.59-66.
  5. 5.0 5.1 5.2 5.3 5.4 5.5 Daynard D, Yassi A, Cooper J E, et al. Biomechanical analysis of peak and cumulative spinal loads during simulated patient-handling activities: a substudy of a randomized controlled trial to prevent lift and transfer injury of health care workers. Applied Ergonomics. 2001;32. 199-214.
  6. Holte K, Westgaard R. Daytime trapezius muscle activity and shoulder-neck pain of service workers with wors stress and low biomechanical exposure. Amer Jour of Industrial Med. 2002; 41. 393-405.
  7. 7.0 7.1 7.2 Frye, Barbara. "Hand and Wrist." Body Mechanics for Manual Therapists: a Functional Approach to Self-care. Philadelphia: Wolters Kluwer/Lippincott Williams & Wilkins, 2010. Print.
  8. Wajon, A., and L. Ada. "Prevalence of Thumb Pain in Physical Therapists Practicing Spinal Manipulative Therapy." Journal of Hand Therapy 16.3 (2003): 237-44. Print.
  9. 9.0 9.1 9.2 Boocok M G, McNair P J, Larmer P J, et al. Intervention for the prevention and management of neck/upper extremity musculoskeletal conditions: a systematic review. Occup Enviorn Med. 2007.;64. 291-303.
  10. Garg A, Sharma D, Chaffin D, et al. Biomechanical stresses as related to motion trajectory of lifting. The human factors society. 1983;25 (5). 527-539.