Back Injuries: Causes, Prevention, and Treatment

As alluded to in the previous post, back injuries exact a large toll on the economy, as well as in the quality of life of the many workers that it afflicts. In order to properly address this issue, we must first identify the factors behind the occurence of back injuries.

Many workers handle loads that are far heavier than they should be handling, given the conditions that they work under in the first place (loads far from body, angle that the load is retrieved at, etc). The conditions listed previously add to the risk, as do the many occasions where the worker is required to repeat these tasks. Together, they add up to an increased risk of injury to the back. These injuries manifest themselves in various ways, resulting from bulging spinal discs, to sudden muscular spasms, to tears and sprains of the tendons and ligaments of back muscles.

How does one avoid such injuries? Bearing in mind that the most effective controls are engineering controls, the work environment should be changed to eliminate or greatly limit the instances where heavy loads are handled, and where back bending is required. Bringing in mechanical aids, reducing the weight of loads by spreading them out among more containers, or changing the material that work objects are made of help to reduce this risk factor. As far as posture is concerned, changing the work orientation so that all loads are situated between 33 and 38" above the standing surface, or at least between 22" and 49" above the standing surface will greatly reduce the instances where back bending is required as a work posture. Further tips of on administrative and behavioural controls can be accessed at the Mayo Clinic's website, on this page.

Regardless of the above measures, some worker may still suffer a back injury. If one of your workers, or if you are afflicted, remember that the "conventional wisdom" regarding laying on your back is largely misguided. While it is a good idea to avoid lifting objects immeadiately after an injury, laying around without movement will inhibit the flow of materials to the injury site, slowing the pace of recovery. In the case of severe, chronic back pain, surgery may be necessary. Consult your doctor if pain is persistent, in spite of initial treatment procedures.

Facts About Low Back Pain

To start off my series of posts on lower back pain and its ergonomic implications, a few facts regarding the disorder to lay the foundation for the rest of the week:

• 80% of the population will suffer from low back pain at some point in their lives (Source: Vallfors B. Acute, Subacute and Chronic Low Back Pain: Clinical Symptoms, Absenteeism and Working Environment. Scan J Rehab Med Suppl 1985; 11: 1-98).
• 50% of the population will suffer from low back pain this year (Source: Vallfors B. Acute, Subacute and Chronic Low Back Pain: Clinical Symptoms, Absenteeism and Working Environment. Scan J Rehab Med Suppl 1985; 11: 1-98).
• Low back pain costs the U.S. economy $90 billion dollars a year (Source).
• Low back pain is defined as any pain caused by injured discs, musle contractions, or other back disorders.
• Per capita health care costs for people with back pain verus those who did not suffer from back pain were 1.6 times higher ($3,498 vs. $2,177) (Source)
• Two types of back pain: acute (sudden onset, lasts for a few days at the longest) and chronic (develops over time, continual or frequently recurring pain)
• Those most at risk for back pain include those who engage in heavy labour, long periods of sitting or standing, people in poor physical shape, those who are chronically exposed to vibration, smokers, etc.

Just a few ways that low back pain is easily one of the greatest ergonomic challenges facing employers today...

Ergonomics In The Blogosphere: BrooklynDodger

I came across Google Blog Search this morning; naturally, I searched for ergonomics. It turns out that the Sunday Spotlight made the first page! Talk about moving up in the world! In addition, I decided to search for other blogs that talk about ergonomics, and occupational health and safety. Of the entries that I found, one blog stood out. BrooklynDodger is a blog that takes research articles, and highlights findings so that they are easily understood by people who have alot on their plate and not alot of time, like myself. Despite the most recent post focusing on something not necessarily work-related (alcohol use and marital satisfaction), most of the content is very relevant to OH&S professionals.

Also, I have now added a site to the list of links on the sidebar at the left. Ergonomics in the Blogosphere uses Google Blog Search to highlight the latest mentions of ergonomics in the vast ocean of weblogs out there, many of which will belong to yours truly!

Sunday Spotlight: The Back Belt

This edition of the Sunday Spotlight is not meant to highlight the attributes of a ergonomics process or device, but to dissuade people from the use of a product that is falsely promoted as being ergonomic. The back belt, first used by weightlifters to "protect" them from injury by "supporting" the muscles of their back. As time went by, those who believed in the effectiveness of back belts extrapolated this theory into workplace situations where work objects were lifted. If back belts "helped" weightlifters, then certainly they would protect the worker from harm in the conduction of their tasks.

Well, do they?

* According to a literature review in the journal Spine in 2001, "... because the randomized trials concerning lumbar supports (i.e. back belts) were consistently negative, there is strong evidence that they are not effective in prevention". (Source: Spine 26(7):778-787, April 1, 2001)

* While far less condemning than the article cited above, a study in the journal Work published in 2003 states that " ... the effectiveness of back belts to prevent back pain and injury remains inconclusive". (Source: Work 20 (3): 257-266, 2003)

* Moreover, even if back belts pose a specific benefit to workers at large, their promotion provides an easy out to those who would acquire them in order to pay lip service to ergonomics and OH&S. An article in The Journal of Occupational Rehabilitation in 1994 states while they left the option of prescribing back belts open to individual practitioners of occupational medicine, they still attached a disclaimer that said that " ... these devices should not be provided as an alternative to appropriate administrative and/or engineering controls". (Source: Journal of Occupational Rehabilitation 4(3): 125-139, September 1994)

In my opinion, the last comment is the most relevant to the debate over the use of back belts as an ergonomic intervention. It is akin to Wile E. Coyote holding up a mini-umbrella to shield him from the coming onslaught of a falling boulder. Wouldn't it make sense for him to step out of the way of the falling boulder, instead of trying in vain to shield himself from overwhelming forces that will hurt him no matter what? It is the same situation with back belts, a useless umbrella employed to deflect the overwhelming forces that are placed on the lower back by overly excessive weights or by continual back bending. It makes more sense to give that person a mechanical assist, or to redesign the workspace so that they do not have to expose themselves to dangerous postures, than to strap a pitiful piece of leather around a person's waist and expect that to protect them from the faults of a poorly designed job.

Back Pain Conventional Wisdom Challenged

I hope everybody is having a great Friday, as another glorious weekend lies before us. If you've hurt your back recently though, this pronouncement may be like rubbing salt in the proverbial wound, as sufferers of back injuries must bear unspeakable pain when doing simple things like sitting down, and tying shoes (forget it, too excruciating!)

I came across an article on msn.ca this morning, challenging several pieces of back injury conventional wisdom. It's a fairly informative article, citing the results of several recent studies. As a result of reading this article, I have been inspired to dedicate time to the subject of low back pain, so next week, I will be focusing on back injuries, prevention and treatment.

Have a great weekend everybody!

Response To Case Study #2: Long-Haul Truck Driver

It took a while, but I have finally settled back into a working routine here in Edmonton.

Last week, a case study was posted on long-haul truck driving: here are some suggestions, based on the identified trouble spots.


Problem #1 -- Boring drives

For many drivers, terrain can be monotonous and boring, causing alertness to wane, thus increasing the chances of an accident occurring. Air flow, music in the cab, and caffeinated beverages (within reason) all help to maintain attention, as does regular rest breaks for 10 minutes every hour or two.

Problem #2 -- Old truck seat

Old seats may lack proper support for the back, and may transmit vibration readily. Obtaining a truck seat that has a lumbar support will allow the lower back to maintain its natural curve, reducing the static forces that punish the back during prolonged sitting. Seats with bases that absorb vibration readily should be a requirement for any new seat that is purchased.

Problem #3 -- Whole body vibration

Many trucks, especially older ones, will vibrate in the cab due to the power of the engine and the truck's suspension. Keeping the truck maintained and in good working order will reduce the amount of vibration that is generated by the truck. Adopting the chair suggested in the previous recommendation will further reduce the amount of vibration that the driver is exposed to throughout their trips.

Problem #4 -- Light glare

Directly or indirectly, sun glare can blind a driver at critical times, potentially leading to a serious accident. Use of sunglasses and sun blinds can reduce the effects of glare if driving cannot be avoided. Ideally, time where the sun is low in the sky could be used as napping time for the driver, avoiding the blinding light of dusk or dawn while increasing alertness through proper rest.


Problem #5 -- Sore Hands and wrists

Over long periods of time on the road, hands and wrists can become sore from continuous soft tissue compression from contact with the wheel, and inadequate blood flow to and from the hand due to prolonged wrist extension. By softening the surface of the wheel, tissue compression is reduced. Backing the truck seat away from the wheel so that the wrist is no longer in extension is also a possibility that should be explored. Finally, change the position of the hands and wrists on the wheel periodically to promote dynamic blood flow.

Problem #6 -- Unfit worker

Due to the sendentary nature of the job, as well as the large food portions at meals that are traditionally had by truck drivers, the drivers are often out of shape. Because of this, their energy levels degrade over time, contributing to fatigue, which increases the risk of accidents. Instituting a wellness program, where proper nutrition is emphasized, as well as the importance of at least 30 minutes of everyday physical activities a day, will increase energy available to the driver, reducing the chances of an incident occurring from fatigue.

Case Study: The Long-Haul Truck Driver

For case study #2, we will profile the truck driver. The operator of this hypothetical truck has the following situations to deal with:

• Long periods of driving on the road, occasionally across boring terrain, and at night.
• A truck seat that is old, and therefore lacks proper support for the back.
• Continuous low-level, whole body vibration from the operation of the truck.
• Contends with low-sun glare, as well as glare from other vehicles.
• The driver complains of sore hands and wrists at the end of the day.
• The driver, from the sendentary nature of the job, is overweight and gets tired easily.

I can't promise an exact date for responding with answers to this case study because I am moving to a new house in Edmonton, Alberta this weekend, and I am unsure of my laptop's ability to connect with the wireless hub there. If everything goes smoothly, expect the next post early next week, on Monday or Tuesday.

Have a great weekend!

How To: Reducing Non-Neutral Elbow Postures

It's been a little while since the last installment in this ongoing series of non-neutral body postures, so today I have decided to focus on the elbow/forearm area. There are 2 main kinds of non-neutral orientation in the elbow/forearm area, and they are (1) Elbow/Forearm Rotation and (2) Elbow Extension.



ELBOW/FOREARM ROTATION

Problem: The operator has to screw in or tighten a work object (e.g. using a screwdriver to insert a screw into a wall), exposing the elbow/forearm to repetitive rotations, fatiguing and eventually causing inflammation in the tendons of the lower arm.

Solution: Acquire a powered tool that will insert or remove screws mechanically. Valves should be maintained regularly to keep rotation forces to a minimum, should be engineered so that rotation is easy or unnecessary, or they should be made large enough that both hands and larger muscles can be used to activate/close the valve.



ELBOW EXTENSION

Problem: The operator has to acquire or manipulate a work object that is located far from the operator's position, forcing them to extend their elbows to complete the task.

Solution: Locate the work closer to the operator, eliminating physical obstacles that force the operator to extend their elbow. Work objects should ideally be located within 12" of the operator's position, and no more than 18" for occasional use.

Ergonomics In The Mainstream Media: Improper Shift Schedules And Train Collisions

I don't know if anybody out there in Canada caught this last weekend, but on Discovery Channel's Mayday: Head-On Collision, they profiled the factors behind the cause of the Hinton Train Collision. In 1986, trains that would normally pass by each other on separate pieces of track ended up, through a tragic series of errors, on the same rail, and smashed into one another at top speed. 23 people were killed, and scores of other passengers on the train were seriously injured.

Alison Smiley of Human Factors North served as an ergonomics expert at the subsequent inquiry into the disaster, and lent her voice to the television special, appearing for a 10 minute segment on the ergonomic aspects surrounding that tragic day.

Despite the fact that warning lights told the conductor of the freight train to stop, the train sped on unimpeded. Why did this come to pass? According to the program, the train conductors were very tired on the day of the incident, getting 5 hours of sleep or less. The collective fatigue of the freight train crew may have caught up with them, as a combination of being asleep on the job led to signals not being sighted and a rigged deadman's pedal kept the freight train on schedule to reach its final, horrific destination.

Why were the conductors getting so little sleep? Why was the Deadman's Pedal rigged with a lunchbox? The conductors got little sleep frequently because when they were working, they were on call 24 hours a day, 7 days a week. Not being able to settle into a pattern of wakeful alertness and sleep, their circadian rhythms were messed up, resulting in low energy levels when awake, as the body thought it should be sleeping when it wasn't. As for the Deadman's Pedal, it was rigged because in order for it to function as intended, the operator would have to keep the pedal depressed for the vast majority of the time in order for the train to run (taking the foot off triggers an alarm fairly shortly afterwards, shutting the train off briefly after that). As it is fatiguing to do this for hours at a time, they rigged the switch so that they could drive the train in comfort.

A perfect storm of these extenuating factors led to the train collision, a day of infamy in the history of Canada. Nowadays, CN has a anti-fatigue system that has been lauded by other in the railway industry, and the Deadman's Pedal has been replaced by pressing a sequence of controls regularly, freeing up the foot from that duty.

Indeed, ergonomics can mean the difference between a MSD and good health, or between a catastrophic disaster and getting home safely.

New Web Resource Added To Link Column

This evening, I added a new link to the left sidebar. Thomasnet is a website that has catalogued the home pages of innumerable companies that sell industrial ergonomic products. Looking for a specific type of conveyor or lift system? Just type what you're looking for in the search engine on the main page, and you're well on your way to finding what you need!

Sunday Spotlight: The Load Leveler

The focus of this week's Sunday Spotlight features a device that allows workers that unload material off pallets and carts without having them place their bodies in compromising positions. The load leveler, which can be found in applications ranging from carts to pallet holders, automatically adjusts its height as weight is added or removed from it, keeping the loading/unloading height at a proper level. This is accomplished through tension springs that compact or uncoil as weight above it is added or removed.

As with any ergonomic technology though, it will be of little benefit if it is not adjusted properly. Ensure that the load leveler functions so that the loading/unloading height falls between 33" and 38" above the standing surface, and ensure the retrieval area near the load leveler is free from obstructions that would make item retrieval difficult. Ideally, a load leveler that rotates would be the best model to acquire, as it allows for nearside retrieval of items that would otherwise require a long reach across the pallet.

Have current or past experience with load levelers? Feel free to share your wisdom in the comments below!

Hedonomics: The Next Step In Ergonomics Engineering?

I found this article when surfing through ergonomics news this afternoon. Turns out the next step in ergonomics is to make work not just easy to perform, but pleasurable! Seems like a logical evolution to me, who wouldn't want to do work that is enjoyable, rather than just easy?

Answers to Case Study #1: Retrieving Stock In A Retail Warehouse

A few things to start off today's post before we get down to business. Over the last week, I have been very busy, making preparations to move from Calgary to Edmonton, Alberta. Henceforth, I have had little time over the past week to blog. Over this week, I should have plenty of time to dedicate to The Industrial Athlete, partly to help make up for lost time. Next weekend though, I will be moving most of my stuff up to my new place in Edmonton, so disruptions in posting may occur again.

Not only did last Friday's post mark the first case study to be examined on this blog, it also marked the occasion of The Industrial Athlete's first commenter. Congratulations SkookumJoe, you have just become a trivia question (i.e. first commenter)!

Staying with the comment that Joe made, he summed up one of the top problems that plague our hypothetical retail stock room...

Problem #1 -- Too much stock

This stock room has too much stock. Rows upon rows of goods that are out of season, or are present in quantities that surpass the "pull" from the consumer. This overstocking problem leads to crowded hallways, making navigation difficult. It causes goods and other non-sale items to be placed on the floor due to lack of space, increasing the risk of tripping and damage to the goods that are on the floor. It also leads to goods that are placed at a height that requires the worker to perform work above their shoulders and to use ladders, increasing muscular fatigue and retrieval time.

The solution to this problem would involve scheduling a lean intervention, putting into place a just-in-time delivery system for goods as they are needed. Goods should be acquired in quantities that address the consumer need for them (e.g. middle shoe sizes should be ordered in greater quantities than small or big shoe sizes) so that the store will not be caught short of the product that the consumer is seeking. Doing this would free up space in the stock room, allowing for easier movement within the area, and easier access to products that would otherwise be on higher shelves.


Problem #2 -- The ladders are few in number, and very heavy

For work that does require a ladder, getting access to one is difficult in our stock room. There are only a few ladders that are in the stock room, some of which are frequently taken by store staff to areas on the floor. The end result often leaves the staff in the stock room with the ladders that are much too high or heavy for practical use. This causes the staff to "climb" the shelves to access the stock needed, or to a dangerous attempt to move the heavy ladder into place.

Acquiring more lightweight ladders would be the step taken in this case. More importantly, a policy should be drawn up to restrict certain ladders to the stock room, while allocating others to the floor. Painting a stripe on the stock ladders would help define a stock ladder from a floor ladder. The heavy ladders should be replaced with stair ladders that have locking wheels that are easy to engage and disengage, accomplishing both ease of movement along with a higher height.

Problem #3 -- Manual material handling of heavy pieces of stock

When retrieving goods from the stock room, some pieces may exceed limits beyond what the worker's body can handle. Improper lifting techniques may be used, increasing stress on the lower back and other body structures. Pieces may be lifted and carried off the stock shelves without assistance, for reasons of self-determination or the activity level of the store. Finally, heavy objects may be located higher than they ought to be located, leading to increased physiological stress on the worker in question.

By using the NIOSH equation, common lifts can be analysed to see if they are safe to perform, given the parameters of the lift itself. If the lifting index is below 1, the lift can be considered to be relatively safe. Between 1 and 3, the lift is considered to be risky, and should be examined ASAP. Above 3, the lift poses a severe risk, and should be examined immeadiately. Proper lifting technique should be taught to workers (keep the load as close to the body as possible, bend with the knees, square up to the load instead of lifting it from an angle, etc), and mechanical assistance or help from another worker should be enlisted if the load exceeds safe lifting limits. If the load is within "safe limits", but the worker feels uncomfortable doing the lift, assistance should be sought before initating the lift. Finally, position heavier items on lower shelves (between 28" to 35" off the standing surface) so that retrieval is optimized, avoiding back bending or overhead reaching. In general, all retrieval of stock should take place between the knees and the shoulders to minimize physical stress on the body.


Problem #4 -- The carts

The carts provided are non-height adjustable, and one of the carts is a cheap box cart, fitted only with a rope for a handle. When unloading stock onto the sales floor, the worker often has to bend over at the back to retrieve items at the bottom of the boxes, causing increased stress to the lower back structures. The rope on the box cart makes it hard to steer, causing frustration and lost time, especially when the cart runs into displays, necessitating pauses to fix the disturbance left by the collision.

Acquiring adjustable height carts will allow the worker will retrieve stock from the cart at an acceptable working weight (between 33" and 38" off the standing surface). If the employer has more money to spare, a cart with an angle-adjustable surface should be considered, which will keep the stock closer to the worker in addition to maintaining a proper retrieval height. Alternatively, look into acquiring a load-levelling cart. They automatically adjust the cart height as stock is removed from the cart, eliminating the need for the worker to re-adjust the height themselves as they go.

Problem #5 -- Lack of visibility at the stock room doors

Finally, the stock room doors often are opened without warning, often striking unsuspecting workers on the other side. This has the potential to injure an employee's hand/head, not to mention scaring the wits out of them!

Putting a glass window will allow parties on both sides to know if anyone is approaching on the other side. Alternatively, a motion sensor could be placed near the doors, alerting workers on the other side to know when another worker is approaching, through an audio alarm. Also, a policy should be instituted where all workers opening stock room doors must open them slowly, allowing anyone on the other side to notice before placing themselves in harm's way.

Case Study: Retrieving Stock In A Retail Warehouse

This post marks the debut of a new feature here at The Industrial Athlete. It takes hypothetical situations in the workplace and asks you to diagnose what could be done to improve the situations from a health, safety, and ergonomic standpoint.

For our first case study, we have a retail stock room where items of varying weight and bulk are retrieved. The details:

• Currently, ladders are used to access high shelves. These ladders however, are few in number, and all of them are heavy (40 lbs +). Moving them alone, as is often the case, is dangerous, and no less fatiguing.
• The hallways between the shelving units are narrow, and carts often get stuck trying to turn around in them.
• The carts, also few in number, are not adjustable, and one of them is a small box cart with a rope for a handle.
• The doorway into the stock room area often swings open without warning, due to the lack of visibility from the outside in.
• In the receiving area, shipments often clutter up the floor in front of accessways to the stock shelves, making transport difficult.
  
  

Using this specific information, along with general knowledge regarding operations in a retail stock room environment, identify ways that this workspace can be made safer and more efficient.

Answers will be posted on Tuesday!

NOTE: Sunday Spotlight will become Tuesday Spotlight this week, due to a trip being made out of town by yours truly over the weekend. See you next week!