Upper Limb Problems Paper

Upper Limb Problems Paper ORDER NOW FOR CUSTOMIZED AND ORIGINAL ESSAY PAPERS ON Upper Limb Problems Paper Explain how work activities cause upper limb problems or only disclose existing conditions using four levels of “causality” ? Upper Limb Problems Paper 2. What factors contribute to ergonomic exposures to musculoskeletal stress? attachment_1 CHAPTER 5: REPETITIVE TASKS, RISK ASSESSMENT AND TASK DESIGN 1 CHAPTER 5: REPETITIVE TASKS, RISK ASSESSMENT AND TASK DESIGN 2 General requirements for humans in systems ?Repetitive, monotonous work should be minimized. ?When repetition cannot be minimized, the optimum combination of force, repetition, posture and duration of task performance must be defined and implemented. ?The risk of injury to the musculoskeletal system must be ALARP (‘as low as reasonably practical’). ?All tasks requiring repetitive movements of the upper limbs should bear a low risk of causing musculoskeletal injury as defined by a Strain Index rating of less than 6 (or equivalent valid and reliable risk assessment tool) ?Repetitive tasks involving the operation of cursor control devices should be carried out with: neutral wrist postures; low forces; low repetition rates and short durations. Upper Limb Problems 3 ?Traditionally 2 schools of thought: ?If a person experiences pain at work, apart from minor aches and pains which are always reversible, the pain is a characteristic of the person or is caused by a disease which would have occurred anyway ?If a person experiences pain at work it must be the work that caused it. People in this camp use the terms “pain”, “disorder” and “injury” almost interchangeably – but if someone complains of a headache at work, is it a head disorder or a head injury? ?Easy to define minimum requirements for health. Large grey area which gets bigger when people refuse to accept discomfort as part of life. Feedback from employers, HFE and the medical profession can amplify the process WMSDs (‘RSI’) as a “Manufactured” Disease: The Sociologist’s view (Arksey, 1998) 4 ?All “diseases” are ultimately socially constructed concepts their recognition depends on the society in which they occur ?As people’s expectations are raised, they are less likely to accept discomfort as “part of life” ?RSI (Repeated Strain Injury) is a socially constructed category for aches and pains experienced at work ?Existence and nature of pathology is unclear Misleading Terminology 5 ?Not a medical diagnosis – at best, a process description but also used as an outcome ?No standard definition – some people use it as a general term for all work-related upper limb conditions (what about knee problems?) ?Others use it only for mysterious pain that doesn’t fit into any known categories ?“Work-related upper limb disorder” or even “regional pain syndrome” are probably less confusing ?Pointless to talk about “keyboard injuries” or “barmaid’s elbow” – we’re really talking about misuse Possible Mechanisms of Tissue Pathomechanics 6 ?Localised fatigue in muscle as a source of pain (inefficient recruitment of motor units) ?Inflammation – tendonitis ?Damage without inflammation – tendonosis (e.g. to extensor carpi brevis radialis in tennis elbow) ?Fibrosis – increase in the extracellular matrix in muscle tissue – matrix is a barrier to nutrients and contains pain receptors ?Experimental evidence for an increase in muscle collagen after exertion WMSD’s: Scratching the Surface: Possible Mechanisms of Tissue Pathomechanics 7 ?Increase in muscle collagen increases muscle stiffness Upper Limb Problems Paper ?Accompanied by decreased shock absorption ?Rehab takes a long time and scarring may never be completely reversed ?“Ragged” red fibres and increased “fatigability” of muscles ?RSI as a form of peripheral neuropathy ?RSI as a disorder of “nocioception” Upper Limb Problems: An Epidemiological View 8 ?Do work activities cause upper limb problems or do they just disclose existing conditions? ?4 levels of “causality”: ?Work exposure is a necessary cause of the disorder (e.g. silicosis, lead poisoning) ?Work exposure is a contributory causal factor but not a necessary one ?Work exposure provokes a latent weakness or aggravates an existing disease ?Work exposes the worker to potential dangers which may increase the likelihood of a disease developing (e.g. alcoholism in liquor industry) Musculoskeletal Disorders in Sportsmen and Musicians 9 ?Disorders of the musculoskeletal apparatus ? disorders due to secondary compensatory techniques ? Tendinitis and tensosynovitis ? Ganglia in the wrist due to friction of tendon against bone ? Dupuytrens’ contractures ? Joints – e.g. traumatic arthritis in drummers. ? Problems due to joint laxity (genetic). Muscular stabilisation of joint ? Job stress superimposed on underlying degenerative process ?Nerve entrapment syndromes ? Carpal tunnel syndrome (pianists, flutists and guitarists) ? Ulnar nerve entrapment proximal to the wrist ? cervical radiculopathies (osteoarthritic spurs, cervical disc disease) ?Disorders of motor function Musicians and Sportsmen 10 ?Disorders of motor function ? Focal dystonias” (occupational cramps) . Poorly understood, lack of definitive therapy. Lack of motor control, involuntary movements, central and peripheral NS factors probably involved. ?For all WRMD’s clinics report a predominance of keyboard players followed by string players ?Wind and brass players are limited in their practice hours (running out of “breath”) ?Females more susceptible than males (play different instruments) ?In all cases, injury is a process rather than an event. A process superimposed on the rest of the patient’s life. Common “Ergonomic” Disorders: Ratings from 1 to 4 11 ?Tennis Elbow ?Tendonitis/Tenosynovitis ?“Insertion” syndromes (“policeman’s” heel) ?Bursitis (e.g. “housemaid’s knee”) ?Rotator cuff syndrome (“swimmer’s shoulder) ?Joint diseases (hip, knee) ?Compartment syndromes (more common in sport) ?Nerve entrapment syndromes (carpal tunnel) ?Other diffuse, difficult to diagnose conditions (“RSI”) ?Occupational cramps (“writer’s cramp” children and biros) ?Myalgia/myopathy Tennis Elbow 12 ?Overexertion of the extensor muscles of the wrist can lead to a condition known as “tennis elbow” (lateral humeral epicondylitis) Tennis Elbow 13 Evidence for Work Relatedness 14 ?From the evidence available it would seem that a “high-risk” job for epicondylitis will be one which requires high grip forces combined with repetitive work in extreme postures or pronation and supination of the wrist ?Essentially factors that increase the stress on the tendon insertions ?Low-friction handles and contaminants such as sweat, oil, and lard that reduce friction (Bobjer et al., 1993) would seem to increase the risk by causing people to grip harder ?Perhaps this is why the disorder has been found in occupations such as fish processing where several different factors operate together. Tenosynovitis 15 Tenosynovitis 16 Risk Factors 17 ?Upper Limb Problems Paper Extreme positions of the wrist can press the flexor tendons of the fingers against the bones of the wrist, increasing the friction in the tendons ?Rapid, repetitive movements of hand or fingers can cause the sheaths surrounding tendons to produce excess synovial fluid ? The resultant swelling causes pain and impedes movement of the tendon in the sheath. This is known as “tenosynovitis.” ?Repeated exposure can ultimately leave scar tissue which impedes movement of the tendon in its sheath and thus degrades function. Joint structure may be degraded by the formation of bony spurs around damaged areas. Carpal Tunnel Syndrome ? Carpal tunnel syndrome (CTS) is associated with forceful and repetitive work alone or in combination with other factors ? Vibration of the hand and wrist is also associated with the condition but extreme postures on their own are not ? Combined stressors such as force and extreme posture or repetition are strongly associated with CTS ? As with tennis elbow, it seems that CTS is more common in “hand-intensive jobs” in fish processing, supermarkets (checkout workers), etc. 18 Carpal Tunnel Syndrome 19 Shoulder Problems 20 Punnett et al. (2000) found an increased risk of shoulder disorder when the shoulder was abducted or flexed more than 90°, with the risk increasing in proportion to the percentage of the work cycle that the arm was held in that position ? High risks were found to occur when the flexion or abduction was held for more than 10% of the work cycle ? There is evidence for a positive association between highly repetitive work (cycle times less than 30 s or spending more than 50% of the time doing the same task) and shoulder problems ? Repeated or static shoulder postures (more than 60° of shoulder flexion or abduction with increased risk when posture is combined with other stressors such as holding a tool) also increase the risk ? Shoulder Problems 21 ? ? ? ? ? ? ? ? ? If possible work with the hands near waist level and close to the body If the hands have to be positioned above shoulder level, their elevation above the shoulders should be no more than 35°. Hand loads should not exceed 0.4 kg and the posture should be held for no more than 20 s for each minute of work Avoid shoulder flexion/abduction >90° for >10% of cycle time Select taller workers for workplaces which cannot be modified Take regular rest breaks Minimize handheld weight Provide external support for the weight of the arms (slings, ledges, etc.) Confine work objects within the zone of convenient reach Provide wrist rests for keyboard workers ? A Shoulder-Straining Task Shoulder Problems 22 Problems Determining Work-Relatedness 23 ? Mainly cross-sectional studies – can’t make causal statements ? Outcomes measured as presence or absence of pain ? Exposure assessments are crude (e.g. job title) ? Lack of evidence of dose-response relationships ? An abundance of confounding variables ? Problems with risk factor epidemiology (plenty of evidence for “risk factors” but we still don’t know what causes the disease). ? Odds ratios have enormous confidence intervals (e.g. 1.2-25) ? Possible solutions: ? Large well-controlled studies across many different sectors ? Small, tightly focused investigations of high risk areas with interventions and follow-up Ergonomic Exposures to Musculoskeletal Stress 24 ?Force ?Posture ?Repetition ?Duration ?Psychosocial strain ?The ergonomic approach is to minimise exposure to factors that might plausibly cause a problem. Lower the forces people have to exert and you lower the strain in muscles, tendons etc. Avoid contorted postures because joints and weaker and tendons and ligaments pre-stressed. Lower the repetition rate and reduce friction and the rate of cell death. Reduce the duration of an activity to permit recovery. ?Differences between work and exercise Force 25 ?Force limits in manual work (University of Surrey) Upper Limb Problems Paper ?Load endurance curve. <20% maximum contraction sustainable for long periods ?Industrial Engineering: Guides for Lifting and Carrying limits (Ayoub and Mital) ?Liberty Mutual Assurance Co. Tables of Maximum Acceptable weights for Men and Women ?Biomechanical Modelling Techniques (SCTL’s) ?Electromyography 26 Biomechanical Modeling Electromygraphy Posture 27 ?Joints in the mid point of the range (except the knee) ?Avoid extreme flexion/extension, adduction/abduction, pronation/supination. ?The human body in “Neutral” ?Muscle length/tension relationships ?How to achieve good postures: Bend the handle not the wrist ? Use handles of appropriate length ? Grip strength maximum when thumb can just overlap forefingers ? Optimum work surface heights defined in functional terms ? The optimum zone 40cm deep, shoulder width wide, hip to shoulder depth high ? Examples of Guidelines 28 ?Hand and Wrist ?? ?? ?? Neutral posture: bend handle not the wrist Avoid use of pinch grip Damp vibration from power tools ?Elbow ?? ?? ?? Avoid high grip forces Use high friction handles Protect against “kick-back” from levers and handles ?Shoulder ?? ?? ?? ?? ?? ?? Keep hands close to body No more than 35 degrees of elevation above shoulders 90 degrees flexion or abduction – less than 10% of work cycle Hand loads < 4kg. No more than 20 seconds/minute Select taller workers for these jobs or fit longer handles Bend the Handle, not the Wrist 29 Repetition and Duration 30 ?< 2000 repetitive movements per hour ?Eliminate jobs with cycle times <30 seconds ?Design out movements requiring rapid acceleration of body parts (e.g. flicking, swatting etc.) ?Rotate jobs ?Design-in micro breaks. ?NIOSH equation allows duration of manual handling operations to be included in risk assessments Risk Assessment: The Strain Index 31 Risk Assessment: Quick Exposure Checklist 32 ?Checklist for use in consultation with employees ?Copy available in Chapter 5 ?Also considers psychosocial stress Other Problems: the Knee 33 Occupational Factors Associated with Increased Risk ? ? ? ? ? ? ? ? ? Occupational knee bending Kneeling >1 h/day Squatting >1 h/day Getting up from kneeling/squatting >30 times/day Climbing >30 stairs/day Climbing >10 flights stairs/day Jumping from one level to another Caring for disabled relative at home (females only) Working in a heavy job >10 years Personal Factors are Associated with Increased Risk High-Risk Occupations ? ? ? ? ? ? Firefighter Farmer Construction worker Forestry worker Miner Carpet and floor layers and tiler Sports ? High risk for soccer and rugby and knee injury Prospects for Prevention 34 ? Can we prevent musculoskeletal pain any more than we can prevent headaches? ? Some evidence for benefits of exercise and the avoidance of exposures to sudden, unexpected forces ? At work, all we can (and should) do is to prevent avoidable stress. Workrelated pain will then take care of itself or be easier to cope with – the problem is to define a daily “dose” or exposure level for different joints/activities ? The perspective of ergonomics is to analyse jobs to identify stressful aspects and recommend redesign. ? Tools and guidelines exist to enable us to do this. ? Shift in management philosophy is needed – the work output may be fixed but the job is open to redesign Epidemiology vs Ergonomics. A Paradox 35 ? Back injury rates unchanged for 50 years despite massive changes in working life ? Looking at the big picture, injury rates and claims data stubbornly resistant to reduction – hence interest in psychosocial factors ? Changes in what we perceive as an injury and what we think are minimum requirements ? Plenty of evidence for the effectiveness and cost effectiveness of ergonomic intervention programmes in industry ? Upper Limb Problems Paper The key to success is to aim preventative efforts at high risk areas ? “Psychological overlay” affects outcomes in all these areas, particularly when there is a “compensation culture” Accident Migration – The Pessimist’s View 36 ?If you improve conditions at work, people will just injure themselves somewhere else ?Rest periods for data entry clerks taken up by knitting ?Might make it easier to cope at work, though ?Some disorders develop over time no matter what you do ?Interventions only postpone disorders or injuries, they don’t prevent them Guidelines for Prevention Programmes 37 ?Commitment by top management: ? ? ? ? Eliminating hazards gets top priority Health and safety of prime importance Accountability and responsibility delegated as close to the problem as possible Provision of resources and authority to make things happen ?Employee involvement: ? ? ? ? Complaint/suggestion procedure implemented to provide feedback Prompt reporting of disorders encouraged Health and safety committees established Ergonomic intervention teams established Guidelines for Prevention Programmes 38 ?Written programme: ? ? ? ? outline corporate goals and plans Advocated at the highest level Communicated to all employees Objectives set out with deadlines ?Review and evaluation ? ? ? ? Analyse trends in injury and illness rates Employee surveys Pre and post change comparisons Record of all job improvements implemented Programme Elements Worksite Analysis 39 ?Examination of injury and illness records ?Identification of problem areas and trends ?Visits to worksites to identify risks ? ? ? ? ? Video/photographs of tasks Measurement of workstations/forces Information on rest pauses Timing of repetition rates Basic postural analyses ?Follow-up when operations change Programme Elements: Hazard Prevention and Control 40 ? Personal Protective Equipment ? ? ? Proper fit Protection against cold Compatibility with rest of task ? Engineering controls ? ? ? Workspaces Work methods Tools ? Work Practices ? ? ? ? Work techniques Equipment maintenance Employee conditioning Monitoring ?Administrative controls ? Increase cycle time ? More rest pauses ? Use more people ? Rotate jobs ? Train standby workers ? Use preventative maintenance Programme Elements 41 ?Medical Management ? Injury and illness recording ? Early recognition and reporting ? Systematic evaluation and referral ? Rehabilitation ? Adequate staffing and facilities ?Training and Education ? General training ? Job-specific training ? Training of supervisors ? Training for managers ? Training for engineers and maintenance personnel Results of Effectiveness Studies Chatterjee 1992. Ford Motor Co. 42 ?Organisational Interventions: ? Steering committee established – management, engineering and occupational health all represented ? Planning and implementation of procedures, ensure appropriate facilities for rehabilitation ? Monitor progress ?Results. Yearly incidence rates for WMSD’s dropped from 2.1 to 0.1 in 3 years. Results of Effectiveness Studies Chatterjee 1992. Ford Motor Co. 43 ?Engineering Interventions: ? Task force established to deal with problems ? better maintenance schedule ? Feed-in and test prototypes ?Occupational Health: ? Emphasis on early diagnosis and job check ? Medical restriction system ?Educational Interventions: ? Education about WMSD risk factors, symptoms and avoidance ? Emphasis on early recognition and reporting ? Basic applied ergonomics course Research Directions 44 ?Demographic changes in some countries suggest a change in capacity of the workforce due to ageing, obesity and a sedentary lifestyle ?These factors will also have to be incorporated into models of WMSDs ?New users, new types of risk – tablets, smartphones and other devices Summary 45 ?No evidence that the workforce is getting younger, fitter or more motivated ?Need to design work so that people can cope ?Role of HFE is to optimise system functioning by fitting the job to the person ?Many guidelines and recommendations available. Something can usually be done ?Continuous gradual improvement more realistic than revolutionary or heroic attempts to solve the problem ?Work related musculoskeletal disorders are also people related musculoskeletal disorders, but at the end of the day, it’s easier to change the work than it is to change people……… … Get a 10 % discount on an order above $ 100 Use the following coupon code : NURSING10

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