Last year while Congress was debating the relative merits and demerits of the proposed ergonomic legislation, I listened to an interesting radio report covering ergonomics in the workplace. The report told how a city bus driver's job was studied from an ergonomic standpoint. I was dying to call the reporter up and say, "You should have studied clinical dental hygienists - our job is an ergonomic nightmare!
To develop an ergonomic risk analysis for a particular job, ergonomists study work-related tasks and look for specific factors that subject workers to musculoskeletal disorders. Three factors that are considered in this type of analysis are numerous repetitions, awkward postures, and exerting force to complete the task.
This short list sounds like a definition of nearly every dental hygiene task we perform. Our profession is full of repetitive stress injury-related risks. It is a small miracle that there are hygienists who are not injured or are not in pain. Other than finding a new profession, is there anything that we can do about it?
Our bodies are not built to take hours and hours of sitting and standing in awkward positions. The foundation of proper body mechanics is based on keeping your body posture in a neutral position as much as possible. This can include keeping the spine straight, maintaining the shoulders in a relaxed position, keeping the head in an upright position supported by the shoulder and back muscles, having the arms close to your side and keeping your wrists straight.
Many hygienists fail to keep their bodies in ergonomically friendly positions throughout the workday, and their entire musculoskeletal system is subjected to constant bending and flexing. There are only so many times the carpal tunnel, rotator cuff, back and neck discs, or thumb or elbow joints can take this strain. So how can we achieve a neutral posture and still practice hygiene?
First, we must know exactly what constitutes poor posture. Since hygienists are not posture experts I asked a Boston-area chiropractor, Dr. Lee Zohn, to give us some insight. Dr. Zohn has developed an interest in the ergonomic risks that dental professionals face daily. He defines poor posture as "... a faulty relationship between the various parts of the body, which can produce increased strain on the supporting structures, resulting in a less efficient balance over its base support."
Nearly everything a clinical hygienist does on any given day can result in poor posture. According to Zohn, our head, hips, shoulders, knees and ankles should be properly aligned to each other. Just imagine dropping a piece of string from the center of your ear straight down. It should pass through the center of the shoulder, center of the hip and fall just in front of the ankle. Dr. Zohn speculates that many dental professionals would find the string hits their toes. This means that our head is too far forward and that we have lost the natural curve in our neck, so that we look like are doing the chicken dance. Unfortunately, people with straight necks have a higher incidence of degenerative changes, often in the form of bone spurs.
Here are a few ways that you can test your own posture. The first is the wall test. Stand with the back of your head and your buttocks touching the wall. Position your heels six inches from the baseboard. Using your fingers as a gauge, check the distance between your lower back and the wall. Then check the distance between your neck and the wall. If you put two or three fingers between the low back and the wall and four fingers or the width of the palm between the neck and the wall, you are close to having excellent posture. The mirror test has two parts: Stand facing a full-length mirror and check the following.
- Your shoulders are level, and your head is straight
- The spaces between your arms and sides are equal
- Hips are level, and kneecaps face straight ahead
- Head is erect, not slumping forward or backward
- Chin is parallel to the floor, not tilting up or down
- Shoulders are in line with ears
- Stomach is flat
- Low back has a slight forward curve
Dr. Zohn suggests that from the side, whether standing or sitting, you should see the three natural curves in your back. From the front, your shoulders, hips and knees should be at equal height and your head should be held straight, not tilted or turned to one side. When the body is positioned correctly, there is minimal strain on the muscles, ligaments, bones, and joints. The internal organs are not compressed, blood vessels are not pressed and nerves are not irritated. This type of positioning allows the body to function at its best. A balanced position causes the least strain on your spine and its supporting muscles and ligaments.
In the clinical setting, a neutral position can be maintained by sitting up straight and positioning your head directly over your shoulders. Keep your elbows close to the trunk of your body with your forearms parallel to the floor rather than having your arms positioned away from your body (looking like an airplane preparing to land.)
If your operator chair has arms, learn to use them for support. Remember to sit all the way back and use the chair's lumbar support. Raise the stool so that your hips are slightly higher than your knees to take the strain off your lower back. When seated, you should be able to feel an arch at the small of your back. If you can't feel this arch, you are probably slouching and hence rounding your lower back. Putting stress on the lower back results in a predisposition to future disc problems. We all experience muscle tension and soreness when we sit for too long. Awkward postures cause the muscles to contract, leading to tissue damage.
Poor posture will result in problems that develop down the road. Perhaps you might think a slouching posture is benign, but the prolonged effects are detrimental. For example, five years from now you might bend down to pick up a pencil and realize you just herniated a disc. Why did this happen - it was just a pencil? The injury can, in fact, be a result of five years of poor posture, increased discal pressures, asymptomatic disc deterioration, and many other factors that predisposed you to a herniated disc in your back. The pencil was just the straw that broke the camel's back.
Remember, always position the patients' heads close to the height of your waist when you are seated. If you must lean forward, do so from the hips rather than hunching up your shoulders or leaning your head forward in an unsupported position. Every time you lean your head forward in an unsupported position all of your upper body musculature is placed at severe risk for injury. If your neck is positioned as little as 2 centimeters forward from a neutral position - which is less than a quarter of an inch - the strain on your shoulder and neck muscles increases tenfold.
Can you honestly say that you never lean forward more than two inches to try and see what you are doing or what you are missing?
Proper operator positioning is nearly impossible to achieve unless you are wearing magnification loupes. Strong reading glasses are not a substitute for loupes. Reading glasses are made with a fixed focal point, which do not allow a clinician to move her head during a procedure. In contrast, magnification loupes are designed with a 4-inch to 5-inch depth of field, allowing clinicians to move their heads within this range and still maintain excellent visual acuity. This is important since the oral cavity is not a flat plane.
Can we learn to eliminate the awkward postural positions that plague clinical dental hygiene practice? The answer is a resounding yes! It is rare that the concept of being neutral appeals to me, but utilizing neutral body postures from one appointment to another, year after year, is the answer for practicing dental hygiene in the comfort zone.
Anne Nugent Guignon, RDH, MPH, practices clinical dental hygiene in Houston, Texas. She writes, speaks, and presents continuing- education courses on ergonomics and advanced ultrasonic instrumentation through her company, ErgoSonics (www.ergosonics.com). She can be reached by phone at (713) 974-4540 or by e-mail at [email protected].