Musculoskeletal Injury Prevention Presented by Roland Reenders Safe Work Manitoba January 25, 2017
Presentation Outline • MSI Hazards • Costs • How an MSI can occur – Back injuries, shoulders • How to reduce risk – Controls – Personal control
5 Hazard Categories • • • Physical Biological Chemical and mineral Psychosocial Musculoskeletal
MSI Definition A musculoskeletal injury (MSI) is soft tissue damage or aggravation in the musculoskeletal system caused when demands exceed the tolerance of connective or related soft tissues such as muscles, tendons, ligaments, nerves, discs and joints.
Musculoskeletal Injuries • Are costly, consider hidden costs
Anatomy of an MSI • Muscles, ligaments, intervertebral discs and other connective tissues have limits on how much they can be compressed, twisted or pulled before they begin to fail. • Injury process: – high loads, short duration (suddenly) – low loads repeated or sustained (cumulative)
Ligaments • Ligaments are like strong, stiff strings that connect your bones together. • If a joint is forced beyond its normal range of motion, the ligament may stretch or tear (sprain).
Muscles • Muscles, via the tendon, connect bones to bones and cause movement. • A muscle used beyond its tolerance can develop a tear (strain)
Discs • An intervertebral disc challenged beyond its tolerance can bulge or tear (herniate)
MSIs – Body Parts 1 2 3 4 5 Back – 47% Neck & shoulders – 15% Legs & feet – 14% Arms & hands – 12% Other & multiple – 11% Almost as many back injuries as other injuries combined!
Back Injuries • So why are there so many back injuries? – Working Positions • Forces acting on the spine • Muscle and ligament stress
Neck loading Source: Kenneth k. Hansraj MD Chief of Spine Surgery New York Spine Surgery & Rehabilitation Medicine New York: Assessment of Stresses in the Cervical Spine Caused by Posture and Position of the Head:
Spine • 33 small block-like bones called vertebrae arranged in slight “S” curve. • Flexible discs between each vertebrae to allow movement. • Discs can become damaged: – Bending/shear – Twisting/torque – Compression
Bending Back disc wedging + shear forces Shear
Twisting / Torque
Compression • NIOSH safe lift limit – 51 lbs; 764 lbs spine compression • Many work tasks exceed safe tolerance, especially when combined with bending, reaching and Compression twisting
Shoulder Postures • Reaching – increases shoulder stress
Shoulder Postures • Reaching
Sitting Posture • Sitting adds stress to the spine and supporting structures • Increased disc pressure • Ab muscles disengage, less spine support • Muscle imbalances, fatigue • Avoid prolonged sitting! Stand Sit
Sitting • Labour market trends 1970 and 2000 • Most Canadians spend 70% of their waking day sitting • Prolonged sitting is linked to many negative effects
Manual Materials Handling
Controls for MSI Hazards • If an MSI hazard cannot be eliminated, there are four main measures that will reduce risk: 1. 2. 3. 4. Engineering controls Safe work procedures (SWPs) Appropriate work schedules Personal protective equipment (PPE) • Ergonomics – “fit the job to the worker”
1. Engineering Controls • Physical changes made to the workstation, equipment, tools and materials • Improve the “fit” of the job to the worker – work in more neutral postures – decrease physical effort when performing tasks – decrease forces acting on the body – be more comfortable
Controls Examples From: Grandjean (1988)
Chairs • Chairs are NOT one-size fits all • Many women sit in chairs that don’t fit • A correct chair fits the user properly
Controls Examples • Office – improve postures
Controls Examples • Office – improve postures
Ball, Kneel Chair ? ?
2. Safe Work Procedures • How to perform a job or job task safely – equipment or devices to be used – safe body positions or movements Safe work procedures 2. 1. 1 • (a)develop safe work procedures for the work; • (b)train workers in the safe work procedures in a manner that ensures workers are able to apply the training provided; • (c)ensure that workers comply with those SWPs.
Postures – Lifting
3. Work Schedules • Modify work schedules to reduce the frequency or duration of an MSI hazard – Job rotation – Task scheduling – Micro breaks – Task variation
4. PPE – What Works?
Follow Up on MSI Controls • Following up will ensure that: – changes to work processes are being followed – changes implemented are effective – job tasks are being performed as outlined in safe work procedures – training is consistent with the safe work procedure • Who should follow up?
Exercise • Exercise can reduce your risk for injury
Exercise • Endurance – core – shoulder blade region – hips
Symmetry • Poor symmetry (imbalances) can lead to symptoms over time
Exercise • Stretch breaks
Exercise • Exercise sensibly
Hazard Controls Effectiveness Personal control Equipment or Engineering Job organization Personal protective equipment Bodymechanics/fitness
Summary • MSI defined • Costs • How MSIs occur – Demands on soft tissues – Back, shoulders • How to reduce risk – Controls • Engineered, SWPs, work schedules, PPE – Exercise
Thank you for your attention Today’s presentation is an overview of the Musculoskeletal Injury Prevention full-day course. Consider attending the full-day session for this and other courses by registering on-line at www. safemanitoba. com
Roles Workplace Safety & Health Branch