3Musculoskeletal System Components The musculoskeletal system includes:Muscles, tendons and tendon sheathsJoints and ligamentsSpinal column and discs= Soft TissueKey Message: Basic introduction to the body systems that can be affectedMuscles: Support and move our jointsTendons: Very strong fibers that attach muscles to bones. Allows our muscle forces to be converted into movement of the bodyTendon sheaths: Membrane that surrounds the tendon and helps movements to be smooth and fluid.Joints: Connection point of several bones to give us a range of movement optionsLigaments: Strong fibers that connect bones to other bones. Provide support and stability to the joint. Can be stretched to the point where they permanently change length. This reduces stability of the joint.Spinal Column: Body vertebrae stacked one on top of another in the trunk. Provides structural support to the body and attachment points for trunk musclesDisc: Shock absorber between two discs. Facilitates motion between spine vertebrae.
4Why MSDs happen? Injury repeated exertion time MSDs can result from repeated loadingtimeTissue loadInjuryrepeated exertionGreat visual of how work-related MSDs progressCumulative movements of high risk tasks, over time…..Age 32 on, the bodies tissue tolerance starts to decrease, we continue to do the same, or more demands of the job, eventually the tissue will breakAgeing population, the worker who has done his job for 20 years all of a sudden his shoulder gets tendonitis…..tissue tolerance has changed.We must work with the older body, understand the physiology, try not to wear it out at a lesser demand
6What should I look for? Signs: redness, heat, swelling, reduced movementSymptoms:pain, discomfort, weakness, tingling, numbness, sleep interruptiontaking anti-inflammatory medicationKEY MESSAGE: What should I look for and how do I know the severity of an MSDMost common sites affected by MSD’s are low back, neck, shoulders, elbows, wrists but can also show up in mid-upper back, hips, knees, ankles, hands.Typically, there is a gradual onset of the symptoms with worsening over time. Sometimes, an acute injury will not fully heal itself, which then leads to worsening symptoms of pain over time.Signs can be physically seen and observed by the person or someone else: redness, heat, swelling, reduced movementSymptoms can only be felt by the inflicted person: pain, discomfort, weakness, tingling, numbness
7Stages of MSD Progression Experience symptoms at work but can continue to workSymptoms decrease with restSigns and symptoms come and go more frequentlyLikely to experience symptoms after workSymptoms & Signs do not leaveNo longer able to workDisturbed sleepKEY MESSAGE: Most MSDs are at stage 3What is the progression of an MSD - RecognizeSleep is VERY importantStages:Experience symptoms at work but can continue to work. Symptoms decrease with rest.Signs and symptoms come and go more frequently and present after work. Pain and other symptoms may interrupt sleepPain, aching and fatigue even at rest. No longer able to work. Sleep disturbance is common.
8Reporting MSD Signs and Symptoms If you have recognized a MSD sign or symptoms or if you have experienced daily pains and strains, talk to a supervisor, start the MSD investigative process…Can’t prove when or where an MSD has started….cumulative micro tears…over time over doing a high risk taskSo important to do RA – omit all HIG MSD risk tasks, the only responsibility of an employerProve that there are NO high risk MSD tasks….Focue on the task (movement) not the individual worker
9Employee Discomfort Survey (EDS) Hand out the EDS survey (MSD Guideline ON, 2005)Anonymous – fill in the areas that are experiencing symptoms at the end of your shift….not a diagnostic toolSupervisors collect the data – summarise finings – subjective data as to where the human machine is breaking downDo another survey in 6 months after risk assessments have been performed, eliminating all HIGH risks…
11Causes of MSDs Primary risk factors: • High Force • Awkward Postures • RepetitionKEY MESSAGE: There will be three primary risk factors to review: force, posture, repetitionCan you give me examples of high force in your work day?Push/pull carry lift…..
12Force – Primary Risk Factor High Forces: Overexertion occurs when the force required exceeds the tolerance of the body’s tissues. The greater the force required, the greater the risk of injuryExamples in Mining?MMH, pushing, pulling, carryingKEY MESSAGE: High Force can lead to an increased risk of MSDExcessive force may cause acute injury or chronic injury through fatigue. Excessive or sustained force can cause fatigue of the muscles, which can wear down the musculoskeletal system.Better to push than pullLifting limits at work?NIOSH lifting standard: 23kg maximum lift – doesn’t take into account the real world
13Posture – Primary Risk Factor If a task involves taking a static or awkward posture, the risk of pains and strains increases.Awkward Posture - Involves bending or twisting away from a neutral posture.Static Posture - The same position held for a long period of time; can be either a neutral or awkward posture.PICTURE: Suggest using something more relevant to mining industryKEY MESSAGE: What constitutes a posture that may lead to increased risk of MSD?A neutral posture is a position taken near the middle of the body’s full range of motion.It does not involve any overextension of motion. It is the most desirable posture as it allows maximum efficiency with the least amount of energy.Awkward posture: A deviation from neutral is considered an awkward posture.As the joint moves away from the neutral midline, the strain on ligaments and tendons increases.When in a stretched position, the ligaments and tendons lose their ability to protect joints.Static Posture: A static posture is a posture that is held for a long period of time. The risk of a static posture is that it requires constant muscle contraction, decreased blood circulation and eventually a build up of metabolic waste products in the cell that can further damage the muscle.
14MSD Hazards – Awkward Postures Awkward postures to look out for…Mining examples – driving LHD trucks, neck rotated, back in flexion high freq.Lifting, holding drills above your headMore?
15Repetition – Primary Risk Factor Repetition is the number of times a task or similar motion is performed per minute, hour, shift, or day.Highly repetitive tasks can cause muscle fatigue, damage to other tissues and, eventually, pain and discomfortKEY MESSAGE: Repetition is the third primary risk factorRepetitive tasks which require one to use the same muscle groups over and over again are at a high risk for MSD development. The lack of time between tasks develops fatigue in the muscles which may increase their likely hood of injuryOne solution…..job rotation – use of different muscle groups.Guidelines:Duty Cycle = % repetition /day30 cycles per minute2 hours/dayCombination of all 3 primary risk factors….HIGH FORCE+AWKWARD POSTURES +REPETITION…..VERY HIGH RISK FOR AN MSD
16Other MSD Risk Factors Secondary risk factors: Contact stress VibrationTemperature (too hot or too cold)Work organization – (Mining piece work)Work methodsContact stress is stress developed from physical contact with a surface: boots on an uneven floor, wrists resting on a keyboard etc.There are two types of vibration: local and whole body. An example of local vibration is Hand-Arm Vibration Syndrome (HAVS or whitefinger) which develops from excessive vibration in the hands (often from hand-held power tools) that constricts the blood vessels in the fingers. Whole-body vibration (WBV) is often experienced in large mobile equipment.The vibrations may damage and stress the musculoskeletal system, especially the lower back region.Cold temperatures cause muscles to contract and become less malleable,presenting a risk of injury. High temperatures can cause fatigue to set in quickly.Work organization factors include job stress or work pacing which can increase strain. Mining risk = piece work….$ more important than health….Culture!Work methods focus on how efficiently the job is set up.Examples?
17MSD Risk Assessment Duration / Time Use the MSD Guideline “Risk Assessment” tool to perform an investigation with all workers – to brainstorm solutions….Participatory ErgonomicsGuidelines:Duty Cycle = % repetition /day30 cycles per minute> 2 hours/dayYou may deem a task is repetitive….case by case
18Reporting a MSD HazardIf you have recognized a MSD High risk factor within your job tasks, talk to a supervisor about it. Get involved with the assessment, find solutions!Reporting must follow with immediate investigation using the tools.Letting it slide, reporting as a medical does not solve the “root cause” – if the high risk task is still there – the human machine will keep breaking down.This step is the GAP in MSD prevention.WSIB stats are not true as medical aid increases frequency count….
20Ergonomics – Controlling Risk Factors Ergonomics ‘fitting the task to the worker’Removing or decreasing high risk factors from a worker’s daily tasks does not have to be expensive or complicated.Some examples of solutions:• Adjustable work benches to match needed height for each worker• Reorganizing work materials to reduce twisting and lifting• Using anti-vibration hand tools to reduce vibrationChanging posturesTaking micro-muscle breaksKEY MESSAGE: An introduction to the science of ergonomicsErgonomics is “the scientific discipline concerned with understanding interactions between humans and other elements of a system (i.e.tools, equipment, products, tasks, and environment). The purpose of ergonomics is “to optimize human well-being and overall system performance by controlling the risk factors associated with MSDs” (i.e. fit the task to the worker).Examples of easy solutions:• Adjustable work benches to match needed height for each worker• Reorganizing work materials to reduce twisting and lifting• Using anti-vibration hand tools to reduce vibration
21Reducing MSD ExposureThere are several steps that you can take to reduce your MSD exposure:Report MSD hazardsWork as a group to discuss solutionsWarm up your body for the dayUse the correct lifting techniqueKEY MESSAGE: These are things that the worker can do to reduce their exposure to MSDsThe supervisor’s role: Once hazards are reported, supervisors can take steps to either eliminate the hazard (i.e. adjustable work benches) or reduce the hazard (i.e. job rotation) or provide PPE to limit exposure to the hazard.Use your “core muscles” – retrain biomechanics
22Lifting BiomechanicsImproper lifting techniques require the muscles of the back to generate 10 times the weight being lifted!How can the forces on the back be lowered?Use your CORE muscle ALWAYS, wide stance, arch low backMust change our adult habits – ie. we only have 5000 “bad lifts” in a lifetime….we don’t want to use them up before retirement!Decrease wear and tear – use your knees, stomach – because we WILL have many bad lifts (getting boxes from the trunk of our cars) that we will not be able to put our knees into the equation – our backs will be ready due to less wasted lifts on silly things such as paper and pens.It takes 28 days to change a habit (Dr. Phil) – must talk/walk through the Lifting 101 for a month – then it becomes automatic for us.Lifting TipsFactors to take into consideration – dimensions/properties of the load, characteristics of the lifter, # repetitions,Keep your natural curve (lordosis) when lifting.Obtain a wide stance – feet wider than shoulder width.Use your abdominal/oblique core muscles at all timesCreeping - When driving, sitting for any length of time, walk around, and re-set tissue clock before lifting.Get out of the car at least once/hour. Discs are at a lengthened, weak position – high risk for injury!Don’t lift heavy items early in the a.m. – no flexion….Disc bending stresses increased by 300%Ligaments by 80%Adams, Dolan, Hutton (1987)Anderson & Ortengren (1974)110 º sitting posture – less force/load than standing posture – don’t stay at 90º, move around, feet up on desk…..5. Kelsey (1975) Variable work- not too much of anything have merit in reducing LBD6. Push rather than Pull7. Unloading boxes : use boxes with handlesLimit max. weight – standards, policies Trunk: slight bend knees, keep lordosis, contract core
23Personal Protective Equipment Personal Protective Equipment (PPE) is not the best solution but may be appropriate in some situations.Examples:Effective:• Well-designed “anti-vibration” gloves• Kneepads for kneeling work• Anti-fatigue matting• Shock-absorbing insolesKEY MESSAGE: There are PPE solutions that can contribute to reducing exposure to MSD hazards.PPE Controls are used as a last resort. Some PPE may not be beneficial to the workers. There are some devices which may reduce the risk of developing an MSD, while others may do nothing, or even increase the risk of injury.A 1994 NIOSH report, “Workplace Use of Back Belts”, concluded:Back belts do not prevent injuries amoung uninjured workers nor are they protective for those who have not been injured.Ineffective:• Back belts• Wrist supports or splints
24Lifestyle FactorsProper exercise and nutrition help keep the musculoskeletal system operating at its peak, and thus helping to prevent injuriesStretch/Exercise: 30 minutes each daySleep > hours idealGood NutritionKEY MESSAGE: Fit and healthy workers are strong workersRegular exercise keeps the musculoskeletal system strong and adaptable, and exercise and proper nutrition help workers to maintain a healthy weight, which reduces strain on the musculoskeletal system.Any movement – walk, breathe – doesn’t have to be high intensityDrink lots of water
25Suggesting a SolutionIf you have recognized a way to reduce your exposure to an MSD risk factor within your job tasks, talk to a supervisor about it.
27Identify the MSD hazards that exist in each of the pictures ACTIVITYIdentify the MSD hazards that exist in each of the picturesActivityHave the participants look at each picture. What risk factors(primary or secondary) can you identify? What controls can betaken (engineered, administrative, PPE)?
29Recognizing MSD Other hazards that may cause MSDs Contact stress Local or whole body vibration (WBV)Cold temperaturesWork organizationPsychosocialIndividual characteristicsLHD Load-Haul-Dump vehicle40 degree AP with neck ~ 88% of shift!
30Some suggestions:Picture 1, housekeeping under conveyor• Force - holding hose, pulling hose, back-pressure from water• Posture - awkward (neck, wrist), twisted back, static• Repetition - repeating job, dependent on length of conveyorsystem• Secondary - vibration (hose)