Occupational Health Tools 2009
Musculoskeletal disorders
Differences between acute low back pain and specific back injuries
| Acute low back pain (ALBP) | Specific back injuries (SBI) |
|---|---|
| Poorly understood causes | Readily identifiable causes |
| Serious pathology rare | Trauma often detectable |
| More difficult to prevent | In theory, easy to prevent because the causes are well known:
|
| Can be effectively managed | Difficult to manage |
| Psychosocial factors important in the continuance of pain | Psychosocial factors less important |
| Secondary prevention is most important - stopping back pain getting worse | Primary prevention is the main aim - stopping it happening at all |
| Responsible for 90% of claims | Responsible for much more than 10% of costs. In some industries, the proportion of SBI may be higher than 10% |
| Employer role: respond to cases that do occur by using ACC publication Active and Working | Employer role: be preventive by using the techniques and information found in the Department of Labour publication Code of Practice for Manual Handling |
Discomfort, Pain and Injury
This integrated approach to Discomfort, Pain and Injury (DPI) covers:
- Acute low back pain
- Serious Back Injuries
- Gradual Process Injuries*
DOL and ACC suggest it is best to think about seven contributory factors that can influence DPI:
- Individual
- Psychosocial
- Work Organisation
- Work Layout/Awkward postures
- Task Invariability
- Load/Forceful Movements
- Environmental
We suggest this approach because one-shot fixes like ‘training how to lift’, ‘adjusting workstations’ or reducing force requirements often do not work when that’s all that is done.
In this Aide Memoir we explain what each of these factors is about, and direct you to more detailed information about each one.
Once you have thought about the whole picture, you will know the best place to look for detailed solutions.
Seven Contributory Factors
Further detail about each topic can be found on the ACC website. Details of where else to look are given for some topics.
1 Individual Factors
(A) Things a person can’t change about the way they are:
- height, dexterity, strength
(B) Relevant things a person can change to some extent about the way they are:
- exercise, sleep, food, breathing, fitness for tasks.
2 Psychosocial Factors
The way a person reacts in and to their social environment and its influences on their behaviour.
It’s often a two way thing - for example: the way a person reacts to pain and the way family, colleagues and management react to people who develop pain.
For more detail:
- look at the page on Stress in this booklet
- New Zealand Acute Low Back Pain Guide, Incorporating the Guide to Assessing Psychosocial Yellow Flags in Acute Low Back Pain. ACC Publication 1038. Go to www.acc.co.nz.
3 Work Organisation
How work is arranged, delegated and carried out - the timing of work, how much is expected, the discretion available in how to do tasks and the order in which they are done.
Detail: See the DOL publications about stress at: www.dol.govt.nz
In particular, see Table 1.2 of the Guideline Healthy Work for an overall approach to making work healthy.
4 Work Layout/Awkward postures
The way work is set up and the working positions people have to adopt to do it. (Traditional, physical ergonomics or ‘Fit Reach and See’.) For example: A short person has to hold their shoulders high because the bench where they filleting fish is not height adjustable.
Detail: look at the sections on Workstation Design, Office Chairs, Visual Display Units, Handtools and Sit-Stand Seats in this booklet. Also refer to the Code of Practice for Manual Handling.
5 Task Invariability
How much a task changes over time. For example: doing the same task all day without job rotation.
6 Load/Forceful Movements
The muscle forces a person has to use to get a job done.
Detail: look at the DOL/ACC Code of Practice for Manual Handling.
7 Environmental Factors
The conditions of lighting, heat, cold, humidity, air speed airborne contaminants and noise that work takes place in.
Detail: look at the relevant sections in this booklet.
Special notes:
(A) Acute Low Back Pain
What can happen when we bend down to tie up a shoelace. It is spontaneous and hard to prevent. The employer role is to react properly once it occurs. We know exactly what to do to make it better quickly. Psychosocial factors (the way people react) can play a big role in outcomes.
(B) Serious Back Injuries
Are thinks like fractures, severe disc problems and co-mordidity. In theory
these are easy to prevent by applying the Manual Handling COP. Psychosocial factors are not so important.
(C) Gradual Process Injuries
These include:
- Occupational overuse disorders (OOS)
- Repetitive Strain injury ( RSI)
- Musculoskeletal Disorders (MSD) and so on
- Carpal tunnel syndrome etc
Gradual Process Injuries
These are also known as “RSI” and overuse disorders and include:
1 Localised inflammations (tendonitis, tenosynovitis, epicondylitis, bursitis)
2 Entrapment syndromes (carpal tunnel syndrome, ulnar or radial nerve compression) and
3 Pain syndromes (myofascial pain syndromes, fibromyalgia).
Prevention focus – this table suggests how amenable the three types are to primary prevention (stopping something happening) or secondary prevention (stopping it getting worse).| Primary Prevention | Secondary Prevention | |
| Localised inflammations | More amenable to 10 prevention. | Important, though less so than for pain syndromes |
| Entrapment syndromes | More amenable to 10prevention. | Important, though less so than for pain syndromes |
| Pain Syndromes | Less amenable to 10prevention. | Psychosocial factors are likely to be barriers to recovery. |
Causative factors – this table suggests how important some of the seven factors are in the causation of GPI, and thus the possible relative merits of focusing on them when attempting prevention.
| Localised inflammations | (a) evidence that repetition (through work organization and/or task invariability), force and posture are risk factors (b) strong evidence that combinations of repetition, force and posture are risk factors. |
| Entrapment syndromes | (a) evidence that highly repetitive work alone (through work organization and/or task invariability) or in combination with other factors and forceful work and hand wrist vibration are risk factors – (b) strong evidence that combinations of force and repetition or force and posture – are risk factors. |
| Pain Syndromes | It is likely that fewer concrete statements can be made, except that individual factors and psychosocial factors may play a more important role. |
These comments stem from the averaged findings about large groups of people.
Each situation requires will be different and will evaluation on its own merits.Patient Handling
| Key principles | Key messages |
|---|---|
| A comprehensive approach is required to prevent back, neck and shoulder injuries to nurses, allied medical staff and carers. This includes a knowledge of injury prevention and injury management principles | This aide-mémoire outlines the essential elements of a comprehensive approach to patient handling as detailed in the ‘best practice’ New Zealand Patient Handling Guidelines. Page 8 of that guideline sets out minimum legal requirements. |
| Policies and planning: A clear policy and a considered plan help ensure everyone works towards a common goal in a consistent way. | The implementation of an effective patient handling programme is a significant task. It requires commitment - in terms of money (investment), management and staff time. |
| Review and evaluation: A systematic and planned approach is required at all levels of the organisation when conducting a review of a patient handling programme. | An organisation needs to know what’s going to enable it to measure progress and plan for the future. There are legal requirements on injury recording and reporting. |
| Risk assessment: The risk assessment process is used to identify the potential risks involved in patient handling and control them. | The risk assessment process takes place at two levels – at the workplace itself, and in relation to the handling of each individual patient. |
| Training and supervision: Training is vital to provide staff with skills to identify and manage the risks associated with patient handling. | Training on its own cannot bring about change. It must be supported with effective health and safety systems, appropriate equipment and safe workspaces. |
| Equipment: Where possible, equipment should be used to help move patients. Equipment is a vital part of implementing safer work practices and should be used in conjunction with safe patient handling techniques. | There is information available about a variety of patient handling aids and equipment on pages 61-98 of the New Zealand Patient Handling Guidelines. Further information can be sourced from the ACC website. |
Facility design:
The aim of facility design is to provide an environment where patient handling can be carried out in an efficient and safe manner to reduce the risk of injuries to both care and patient.
In practical terms this means ensuring that facilities are suitable for the techniques and equipment required for safe handling, and encourage patient independence to reduce the need for handling. A few key elements are enough space:
- around beds
- to move through doorways and in corridors
- in toilets and bathrooms
- for storage of mobile hoists within 20 metres of where they are needed
The various laws (E.g: HSE Act) and standards for building design do not cover patient handling needs adequately. Recommendations regarding facility design are covered in pages 101 – 132 of the Patient Handling Guideline.
Employee responsibility:
Employees need to fit in and support a comprehensive patient handling programme.
They have a responsibility to do the right things, as far as possible, in support of patients and their colleagues. These responsibilities include:
- attending training and implementing its intent as far as is possible
- reporting hazards to management
- reporting injuries and accidents
- and co-operating with the employer in matters of health and safety.
Monitoring, recording and reporting are legal requirements. Without this data there can be no effective evaluation and planning.
Further information
All Key Principles and Messages are comprehensively documented in the New Zealand Patient Handling Guidelines.
Call ACC on 0800 844 657 or download the various ACC and Department of Labour publications referred to here from www.acc.co.nz and www.dol.govt.nz respectively.
Ergonomics
Sitting and standing at work
Prolonged standing or sitting are both undesirable. A choice between the two needs to be given in many sorts of work.
Significant health effects have been shown to occur after prolonged standing and suggestions of health effects exist for prolonged sitting. Discomfort and fatigue are both clearly associated with prolonged sitting and prolonged standing. Therefore a decrease in effectiveness must also be expected in workers such as:
- Bank tellers
- Restaurant staff
- Health care workers
- Shop assistants
- Postal workers
- Laundry staff
Word of mouth has it that current retail practice regards sitting shop assistants as ‘unprofessional’ or that they cannot be ‘customer responsive’.
There is a need for shop assistants to:
- be vigilant for shoplifting
- be at the same eye-height as customers for clear communication
- to be active in re-stocking shelves and keeping displays neat.
However, the blanket rejection of any sitting is poorly informed – and not conducive to productive work in the overall sense.
Sitting all day
Attention has recently been drawn to the health effects of sitting for prolonged periods on aircraft flights. Consequences are thought to be a slightly increased risk of Venous Thromboembolism – referring to both deep vein thrombosis (DVT – or the process by which a blood clot forms in a vein) and pulmonary embolism (PE – when the blood clot travels to the lungs).
A slightly increased risk for these conditions (but one that ‘does not justify social alarm’, according to one group of researchers) has been detected in airline passengers.
Note that airline passengers are virtually confined to a seat for the duration of a flight but office workers who ‘sit all day’ rarely do so.
However, one study of self referred people showed a suggestion of a link between prolonged sitting in the weeks before an incident of DVT or PE. The people were sitting for periods of 3-6 hours without any getting up at all and spent 8 hours in total sitting per day.
Standing all day
The plight of (usually female) shop assistants who have to stand all day has been the focus of concern for decades. In the early 1870’s and 1880’s it was taken as a given that this was unhealthy to the extent that, in 1880, the Lancet in the UK launched a campaign against this ‘cruelty to women’.
Wearing high heels will, of course, make the effects of prolonged standing worse.
In the 1930’s the UK Government wrote a requirement for seats for workers into the Factories Act and, from 1946, New Zealand legislation has had a similar requirement.
Concerns named include:
- Varicose veins and circulatory problems
- Leg and back pain
- Difficulties in pregnancy
Evidence
There is good evidence that standing all day poses a significantly increased risk for varicose veins. There is evidence that prolonged sitting may pose a small risk for DVT and PE.
Legal
The intent of the HSE Regulations 1995 (Sections 5(2), d and e) are to provide relief from the effects of constant standing. They do not imply that people need to be able to sit down all day or take a sitting break whenever they wish.
Studies in industry show that people (who are able to choose) seem not to choose to sit all day. Workers using 900mm high benches in one factory, for example, chose to use a sit-stand seat (see below) for between 25 and 40% of the day, for certain tasks.
Tall chairs/stools
Sitting on a tall stool without a backrest or footrest is worse than standing.
Without support for the feet and lumbar spine, discomfort and fatigue will develop quickly when sitting on a tall chair.
Sit Stand Seats
Sit-stand seats are a good alternative to tall chairs. The main feature of the posture when using one is that the hip angle (the trunk - thigh angle) is open. This means that a backrest is not required.
The open posture:
- relieves tension in the erector spinae and gluteus maximus muscles
- tends to promote the correct shape of the lumbar spine and reduce pressure in the intervertebral discs –
- all without needing a backrest.
The reduction in stature should be less than 20 percent of normal standing height, in which case users will be able sit while working at a bench, as long as knee space is OK – and retail assistants would be able to scan for shoplifters.
Note that sit stand seats and tall chairs can get in the way when people get off them. If they clutter the space available to move around in they may be unsuitable for some locations (e.g: bank tellers).
Office chairs
| Chair element | Recommendations |
|---|---|
| Dimensions of the fixed aspects of the chair |
|
| Adjustability |
|
| Ease of adjustment |
|
| Armrests |
|
| Seat pan |
|
| Swivel |
|
| Legs and base |
|
Using a computer workstation
Head
- Face straight on – don’t turn your head to one side.
Shoulders
- Keep your shoulders low and relaxed.
Elbows
- Keep your elbows close beside your body
- Bend them between 90o and 120 o when keying or mousing
Lower back
- Support your lower back on the chair’s lumbar support.
Thighs and hips
- Your thighs and hips should be about parallel to the floor
Knees
- Your knees should be the same height as, or just below, your hips, with the feet slightly forward of the knees.
Feet
- The feet should be fully supported by the floor or a suitable footrest. They should not be resting on the base of the chair as this can mean too much bending of the knees and increase the pressure on the back of the legs and knees.
General
- Avoid sitting in the same position for long periods.
- Recline the chair back slightly or tilt the seat pan down slightly to alter body position from time to time.
- Take frequent breaks away from the computer to prevent fatigue. These breaks should be more often than the regular morning, lunch and afternoon breaks.
- Frequent short breaks are better than fewer long ones. A five minute break for every 55 minutes worked is recommended.
- Breaks should involve a complete break away from the computer, i.e. the break should not involve surfing the Internet or dealing with emails.
- Do exercises
- Make use of alternative tasks to relax - filing, standing to talk on the phone - any opportunity to move about the work environment.
- Change eye focus by looking at a distant object (over two to three metres away) every 10 minutes to give the eyes a rest.
- Keep a soft touch on the keys. Avoid ‘hammering’ the keys or overstretching the fingers to reach function keys. Learn to touch type.
Visual Display Units
| Item | Basic recommendations |
|---|---|
| Keyboard | Adjust the keyboard slope and position to avoid awkward upwards or sideways bending of the wristsProvide a minimum space of 150 mm in front of the keyboard to rest the hands and wrist when not keying.Make sure the keyboard is no higher than 30 mm at the ‘asdf…’ row of keys. |
| Screen | Adjust the height of the screen so that the top of the screen is at or just below eye level.Place the screen at a comfortable distance that allows the text to be read easily Keep the surface of the screen clean.Adjust the brightness and contrast controls on the screen to suit the lighting conditions in the room.Ensure the screen is free from glare or reflections.Set the text size or zoom so that text is large enough to read easily at the chosen screen distance.Ensure that the individual characters on the screen are sharply focused. There should be no flicker or movement. An image refresh rate of at least 85 Hz is recommended. |
| Mouse or input device | Keep the mouse within easy reach and positioned so it can be used with a straight wrist.Move the keyboard out of the way if you are using only the mouse. Use a narrow keyboard of a detachable numerical keypad if you use your mouse a lot (to get mouse closer to user).Support your forearm on the desk when using the mouse. Hold the mouse with a loose grip and rest your fingers lightly on the buttons.Select a mouse that fits your hand well and make sure the buttons lie under the fingers and are easy to click.Locate the mouse on the same level as the keyboard Know how to setup the mouse. Consult: “Start – Control Panel – Mouse” (or your system administrator) to alter the mouse settings – its speed, acceleration, pointer trails, left- or right-handedness, scrolling speed, double click speed etc. |
| Workstation | Depth – a minimum of 800 mm for an LCD or 950 for a CRT Height –adjustable (610-760 mm) so you can maintain your elbow at 9O˚-120˚ or (670-700 mm if fixed in height)Knee and foot room should be adequate. Thickness of desktop (no more than 30 mm) with round edges.Ensure there is enough desk space for any documents or other equipment. You may need to provide a larger desk if the user has to read and write while at the computer (a minimum width of 1600 mm is recommended). |
| Footrest | Height – between 50-185mm and slope 0˚-10˚Area – large enough to allow variation in foot position |
| Laptops | A docking station can be useful when using a laptop Use an external keyboard and mouse.When travelling, take other equipment: e.g: external mouse, extension lead – to allow flexibility for set up when travelling |
| Copy holders | Use one – to allow for more comfortable reading of text with less neck bending. Ensure they are large and strong enough to hold everything. |
| Environment | Space: 9-25 sq. metres per person is the suggested rangeThermal comfort: Summer (light clothing) temp 23°-26°C, average airflow velocity 0.1–0.25 m/s. Winter (heavy clothing) temp 20°-24°C, average airflow velocity 0.1–0.15 m/s. Humidity around 50%.Ventilation: 10 litres of air per person per second is the current standard but 25 litres per person per second is preferred.Noise: The recommended maximum average level for background noise is 45dBA at the position of the computer user.Visual conditions: For computer tasks, an average illuminance of 500-750 lux.Where possible, place workstations at right angles to windows.Windows and skylights should have adjustable blinds or drapes to control excess light. |
Hand Tools
Key principles
Hand tool selection is influenced by:
- the type of grip used to hold the tool (power grip or pinch grip)
- the force applied to it (high force requires a handle diameter of 32-50 mm and a handle length longer than the palm width)
- the position of tool use
- the height of the work
- the repetitiveness of the work (power tools may be needed for repetitive work).
Pinch grip.
Power grip.
Critical features of hand tool design are:
- one-handed tools: handle diameter, (32-50 mm power grip; 6-12 mm pinch grip) handle length (100-120 mm for high force tasks), tool weight – a tool suspender may be needed.
- two handed tools: in addition, handle separation, trap points
Bent-handled pliers are a good idea if used in an appropriate position.
Avoid the following actions:
- having a bent wrist when using a tool
- repeated rotation of the forearm (a powered tool may be required)
- working with raised shoulder or elbows held out (alter the work height).
Bent-handled pliers are
of no advantage in
horizontal positions.
Provide the tool with:
- comfortable, soft, non-slip handles
- for two handed tools: spring-opening
- for powered tools: large triggers (at least three fingers).
- Avoid pinch points, sharp edges, finger grooves.
Tool selection can affect shoulder posture. Use of a short shank screwdriver is indicated here.
| Item | Design features |
|---|---|
| Hammers |
|
| Double-handled tools used for power tasks |
|
| Double-handled tools used for precision tasks |
|
| Large screwdrivers |
|
| Precision screwdrivers |
|
| Scrapers |
|
| Saws |
|
| Hacksaws |
|
Repeated use of a tool like the one shown below may cause damage to the palm.
Double-handled tool openings need to be neither too small nor too great. They should also be spring loaded.
Reference: A Guide to Selecting Non-Powered Hand Tools, NIOSH. Cincinnati. DHSS publication 2004-164. (The pictures were taken from this publication.)
www.cdc.gov/niosh/docs/2004-164/default.html
Workstation design
| Aspect | Key principles |
|---|---|
| Postures |
|
| Movements and effort |
|
| Anthropometry (body sizes) |
|
| Sitting |
|
| Standing |
|
| Workstation design |
|
Download the New Zealand Patient Handling Guidelines from the ACC website
- Full document [pdf file, 6.976KB, 213 pages] External link
- Chapters [External Link]