March, 2016 | ergovet

Surgical Ergonomics: Movement and Posture

In order to find pictures to demonstrate surgical posture, I went again to Google images to find some pictures of spaying and neutering, and came across several with surgeons in what appeared to be uncomfortable and ergonomically risky postures. Here are a couple of photos that I found:

https://images.app.goo.gl/7Fhew62NGyxoGRe96

https://images.app.goo.gl/QmP7Mmq6uqSUKyGh7

Both of these pictures show trainee surgeons leaning over their patients with about a 90 degree neck angle, bent waists, and elevated shoulders. We can’t know if these surgeons are using their bodies in this way because of the way their surgery room is set up, or because of habit, apprehension, or unawareness of their posture– or all of the above. Maybe these are brief positions during the surgery – but if these postures are sustained through a surgery day, these individuals are likely to experience some pain as a result.

In small animal surgery, we can achieve a fairly neutral posture except for our neck position. A neutral neck position would involve flexion of less than 10 degrees, but for a surgeon it is often 20-30 degrees. In this picture, I have a neck angle approaching 40 degrees.

It may not be possible to avoid extreme neck flexion in this work, and the important thing will be getting out of this posture between surgeries to allow those muscles to release and stretch. Turning your neck to each side, rolling your head, extending your neck, and shrugging your shoulders are all ways to release the tension in the muscles around your neck.

Other surgical postures to watch out for can be twisted or asymmetrical postures. If a surgeon maintains an asymmetrical or twisted posture, that can lead to uneven muscle use and strain and discomfort at the end of the day.

However, varying position during the surgery day is a good thing. If this surgeon balances the twist in one direction over time with a twist in the other direction, then she may not experience strain from the posture.

In this case, this surgeon might be more comfortable with a foot stool to rest her foot on, rather than using her weight-bearing foot as a footrest.

Another important thing you can do for yourself is to move during the surgery day. Between surgeries, take a few seconds to change your position. Roll your neck and shoulders, stretch. walk a few steps.

A study on human surgeons (abstract here) showed that taking a 20 second break every 20 minutes can increase your comfort and decrease fatigue after a day of surgery, and it can sustain your surgical performance and accuracy better through the surgery day. (If you can get access to the article, it’s a fun read not just for the scientific finding but also for the authors’ wry humor).

We are fortunate in spay neuter that we have short-enough surgery times that we can use the end of each surgery as a cue to move a little. We aren’t doing hours-long surgeries where we would need to set an alarm to remind us to move (although if you are someone who does long-duration surgeries, setting an alarm could be a good way to remind yourself to take your 20-second stretch break). So take a moment when you switch from one surgery to the next, to break the muscular tension that you hold during surgery.

We don’t necessarily think of or talk about spay neuter surgery as a sport or an activity that requires physical fitness or work hardening, but it does. As you do this work, your ligaments adapt, if you give them the recovery time they need between use.

Ligaments adapt to exercise and use by increasing size, strength, and collagen content (given adequate rest and recovery time between uses)
Surgeons in regular work may have greater resilience due to this tissue adaptation
New HQHVSN surgeons (or those returning from an extended break such as a maternity leave) will not have the ligament strength and may be at greater risk for hand/ wrist injury and discomfort.
Consider having a lighter schedule for new/ returning surgeons to allow their bodies to become conditioned to the work. Gradual increases in work hours, rather than starting off with a full-time schedule, may be more likely to lead to well-adapted ligaments rather than injury and strain.

For a much more in-depth discussion of ligament physiology, check out Ligaments: A source of musculoskeletal disorders. If this link isn’t available (it is not from the original publisher’s site), you can find other versions posted on Google Scholar.

Solomonow M. Ligaments: a source of musculoskeletal disorders. Journal of bodywork and movement therapies 2009;13:136-154.

Finally, physical activity outside of work is important to reducing physical discomfort while at work.

Physical activity outside of work is known to be associated with lower prevalence of pain
Surgeons who are physically active experience less fatigue due to work
For people experiencing low back pain, maintaining daily activities as much as possible is associated with quicker recovery from symptoms
Staying physically fit, maintaining friendships outside of work, eating well, and maintaining a work-life balance are all ways to reduce work-related musculoskeletal discomfort and stress.

There are not specific activities or exercises that research says are “best” – and it will likely vary between individuals– the key is simply being active and moving.

I hope this series of posts about surgical ergonomics has given you some ideas of how you might improve your own comfort during surgery. Remember that taking videos or photos of yourself during surgery can be a great way to understand what you are doing with your body, and to start to make improvements.

Let me know what works and what doesn’t work for you, and make comments with questions and with your own experiences of surgical ergonomics.

Surgical Ergonomics: Instruments and Needles

How much force does it take to close and open the ratchet on your needle holders and hemostats? Do you have certain instruments that are more stiff or require more force?

It should not take a lot of force to open and close the ratchets on most surgical instruments. Over the course of a surgery day, repeatedly having to apply extra force due to stiff instruments can add to the trauma on the surgeon’s body.

There aren’t many studies or other publications on the subject; one that I have found is an article by a South Australian surgeon, Michael Patkin.

Patkin M. Surgical instruments and effort referring especially to ratchets and needle sharpness. The Medical Journal of Australia 1970;1:225.

Patkin has an interesting website as well with plenty of thoughts and observations on human surgery and ergonomics.

There is not (at least that I am aware) any standard for optimal force required to open or close instruments, but based on my reading of Patkin and my own experience in surgery, I suggest aiming for about 3 pounds of force to close the first ratchet, and about 1 pound of lateral force to open the ratchet.

needle holder on scale — My favorite needle holders coming in at 2 pounds 14 ounces to close the ratchet. Do you need to go to the trouble to test your own instruments? Probably not, unless you’re curious or just nerdy.

Thumb forceps can also be stiff and difficult to operate. Often, the larger thumb forceps are stiffer than the smaller Adsons or Adson-Browns. If you are experiencing difficulty with your non-dominant, thumb forcep hand, consider choosing a smaller thumb forcep that closes with less pinch force.

In order to reduce the force required by instruments and needle holders, try the following:

Make sure that you are using good protocols for cleaning and processing
Get scissors and needle holders sharpened and get jaws replaced when they get dull or smooth.
Discard needles when they are dull. It takes extra force to penetrate the tissue with a dull needle, and causes extra tissue trauma for the patient.
If you have the chance to make purchasing decisions, choose instruments that don’t require a lot of force to open and close.

Your hands and the patient’s tissues will thank you!

Surgical Ergonomics: Performing surgery

Spay neuter surgery involves a combination of repetitive movements that can at times require force, or may be performed with awkward positioning of the hands and wrists. Each of these factors alone is only moderately associated with pain, but put together there is a strong association with hand and wrist pain.

In any high volume workplace, there will be repetition; it’s unavoidable. Fortunately, many high-volume surgery techniques can reduce some of the repetition.

For example:

Pedicle ties mean fewer suture knots (i.e., less repetition of knot-tying motion)
Shorter incisions mean fewer sutures placed, and fewer knots tied
Efficient technique in general means less wasted motion

In case you are not familiar with some of these techniques, I have included some links and videos so that you can learn about them.

Pedicle Ties are an autoligation technique used in feline spay surgery on the ovarian pedicles. For a peer-reviewed study on the safety of pedicle ties, see this article by Miller et al. The abstract is available here. Pedicle ties are a safe alternative to the use of sutures for ligation in cats, and can decrease surgery time. And shorter surgery time means less trauma for the cat and for the surgeon.

Here is a video of several pedicle ties:

Shorter spay incisions are achieved with practice. The incision needs only to be long enough to deliver the uterus through the opening. Use of a spay hook (on cats and dogs, not other species) is helpful in allowing a smaller incision. It is worth the practice time it takes to be able to make a short incision. As with pedicle ties, short incisions allow for shorter surgery time, less repetition, and less trauma to the animal and the veterinarian.

Here is a video of a cat spay using a short incision and a pedicle tie:

Want to learn more about high volume techniques? Check out Humane Alliance’s E-Learning resources.

So, high volume techniques can decrease the number of repetitions of any given action– but how else can a surgeon lower the risk of hand and wrist pain?

Sustained awkward or tiring positions can lead to discomfort. The pinch grip used for thumb forceps is a common example of an awkward, tiring grip. Some spay neuter vets minimize the use of thumb forceps during closure. This reduces the trauma to skin edges, and also reduces strain from the pinch grip, so it can be a win-win situation.

pinch grip

Other awkward or extreme postures are rarely necessary in spay and neuter surgery, but they may be something that you are using without really realizing it. This is a great reason to get video of yourself doing surgery.

You can find awkward spay pictures from the internet (see one below) that show a large amount of wrist flexion or extension. These positions are all OK, as long as they are comfortable and not sustained or repeated for a lot of time. If they become uncomfortable, or if the surgeon is spending a lot of time in extreme or awkward positions, then it’s time to think of other ways to perform the same surgical tasks.

Here are some arm positions during suturing that are near the extremes of their ranges of motion. Again, there is nothing inherently wrong with having positions that are at the end of the range of motion. But, if they become uncomfortable or inefficient, or they are sustained or repeated often, then the surgeon will need to try alternative positions to achieve the same tasks.

supination pronation ulnar deviation (These vets have wires and stick-on electrodes on their arms because they were a part of my Masters’ research project).

There are a lot of different ways that spay neuter vets hold their needle holders. Some spay neuter vets swear by using the palm grasp, whereas others have never used it. It turns out that the amount of muscle use and the range of motion is so variable between different vets that I can’t really make generalizations about muscle strain.
tripod grasp

This is another case where photos and video are helpful. If the motions of surgery and grasping instruments are uncomfortable, then that may be a cue for the surgeon to consider learning a different grasp style and seeing if the changes in grasp take strain off the uncomfortable body areas.

There are also times when surgical technique can change your whole body posture. In this illustration, the vet is doing a continuous SQ closure from left to right. In order to position the needle, she is twisted around, leaning over, and has a raised elbow.

surgeon leaning

And here is me doing the same thing.

Untitled

It wasn’t until I took this video that I realized how awkward this is, and after a little research I realized how easy the solution could be. Just by doing the same closure from right to left, the surgeon can avoid all the twisting and leaning.

better posture The moral is, if you’re doing something really awkward, there is probably another solution that is a lot smoother and easier.

In addition to repetitive motion and awkward position, forceful motions are the other contributor to hand and wrist pain. The most common times when a spay neuter vet has to use force is during suturing and knot tying, and during castration of large male dogs.

suturing Choosing a suture size that is bigger than what you need for a given surgery means that on every throw of every knot, you will be applying more pounds of force to your ligaments and muscles. Over the course of a surgery day, that’s hundreds of times that you’re applying that extra force.

So in addition to being good surgical practice to select appropriate suture size, it’s also good ergonomic practice.

With the big dog neuter, the spay neuter vet can be using a combination of force and awkward posture to exteriorize the testicle.

As you can see in the illustration, the surgeon has to have a firm grasp and may be pulling with a substantial amount of ulnar deviation– so the wrist is canted towards the pinkie finger. This can be challenging for people with discomfort anywhere in the upper quarter of their body, from hand, wrist, and elbow, to shoulder, neck, and upper back.

dog neuter Some alternatives that decrease this strain could include

Open castration
Sharply dissecting the fibrous attachments around vaginal tunic and between tunic and subcutaneous tissue
Using a hemostat to clamp the cord just proximal to the testis once the spermatic cord is exposed, to provide a more favorable grip for applying traction, rather than grasping the testis itself

dog neuter hemostat

So, as you can see, there are some options for avoiding the three biggest combined risks for hand and wrist pain: repetition, force, and awkward posture. Next post, I’ll talk about instruments and needles.

Surgical Ergonomics: setting up the physical space

In this post, I will share some ideas about how to set up the physical space in surgery.

I want to start by encouraging you to take photos or video in order to evaluate your surgical ergonomics and body posture. It’s hard to pay attention to your body posture while you’re in the middle of surgery. Even if you are trying to pay attention to postures and positions, you may not be able to know or evaluate your posture without a view from the outside. By taking video, you can later watch yourself and find problems that you can then make a special point of changing during your next surgery. The technology is so accessible now– a smartphone or digital camera is all you need. You can prop a phone on a box of gloves; tape it to an IV pole, tape it to a surgical light, or use a tripod.

In the picture here, I had set up video of myself from above and behind because I was having shoulder and upper back pain after surgery days, and this helped me figure out when I was tensing up so I could work on that.

dog neuter screenshot

The physical environment includes things like the height of your surgery table and how you position the patient and objects in your space. These factors influence the way you use your body– and changing them doesn’t have to be difficult or expensive.

In this first example, the surgery table is too high, so the surgeon has to raise her shoulders and abduct or raise her elbows in order to reach the patient. This puts strain on the upper body, especially the neck and shoulders.

table too high

In the second picture, the surgery table is too low, so the surgeon has to lean forward in order to reach the patient. This could place strain on the neck, upper back, and lower back, and perhaps also the shoulders.

table too low

When the surgery table is adjusted comfortably, the surgeon can stand with a relaxed upper body and arm posture.

table correct height

In general, the easiest table height for a relaxed posture is one in which the hands fall about 5-10 centimeters – or 2-4 inches– below the elbows. This means that the table height will need to be adjusted between large, deep-bodied dogs and small patients, in order to keep the surgeon’s upper body in this relaxed position.

Not everyone has access to tables that adjust adequately, but this doesn’t have to mean that you are condemned to upper body strain. Low tech solutions like step stools or platforms, bed risers, blocks, and other boosters can help get you and your patient to a comfortable height.

Another positioning issue that comes up sometimes is that a tiny patient is placed in the middle of a surgery table, so that the surgeon has to reach a long way to the patient, or bend forward. A lot of reaching and bending can put strain on the upper and lower back and shoulders.

too far

If you have a surgery table that you can lean your body against as you work, you may find that it’s comfortable to work with a patient in this position. However, if your table moves when you lean on it, then you may be straining yourself to reach like this. If you do find yourself bending and reaching forward to reach a patient in the middle of the surgery table, consider just positioning the patient closer to you.

patient closer

When we talk about positioning, also remember to look at other objects in the surgery space. Are there objects that the surgeon has to work to avoid, or has to work to reach?

The surgeon in this picture is having to lift her arm and elbow way up to avoid the instrument tray. It’s great having the instruments nearby and in easy reach, but this tray would work a lot better if it was lower or further away, or even if the instruments were on the table between the patients back legs.

Most spay and neuter vets stand for surgery. Its what we were taught in school, and many of us don’t think about sitting unless we have to because of injury or for comfort during pregnancy.

But research with human surgeons showed that they were less fatigued if they either sat for surgery, or alternated between sitting and standing. So if you haven’t tried sitting during surgery, it may be something to consider at least some of the time to increase comfort during surgery.

Sitting for surgery is pretty straightforward when it comes to a small patient. It’s possible to use a standard stool or chair and get close enough to the patient to remain in a comfortable posture

sit for surgery cat

However, it can be more challenging to stay in a comfortable position when doing surgery on a large, deep-bodied patient. A surgeon sitting on a standard stool or chair may have to raise her shoulders and elbows to clear the patient’s body. In this scenario, it’s not possible to lower the table or raise the surgeon’s height because the surgeon’s legs are already in contact with the underside of the table.

sit surgery dog

There is a solution–using alternatives like a saddle-shaped seat or a sit-stand stool can help by allowing the surgeon to remain close to the patient while achieving a better relative height

sit saddle stool

Finally, I want to mention some other aspects of the physical environment in surgery that can affect surgeon comfort and fatigue. Research shows that floor mats can decrease lower limb discomfort and fatigue. They sometimes get credit for helping relieve back pain, but that isn’t supported by the research.

floor mats in surgery

The “perfect mat” will be one that’s not too hard and not too soft. The best mat will be a matter of personal preference. You want something that is cleanable and non-slip. Try out a variety of mats whenever you get the chance to see what feels best to you. Also, look online to ask for a (small) free sample mat from a supplier like Aspen or Smart Step, or a one month trial from other suppliers, so you can see what works for you.

As with floor mats, there is no perfect surgery shoe. But in general, wearing shoes with cushioned soles while in surgery will be the most comfortable, even if you are standing on a floor mat. Some studies of industrial workers found that people who wore different shoes on different days were less likely to have plantar fasciitis than those wearing the same shoes every day. Cushioned athletic shoes or rubber clogs can be good choices.

Next post, we’ll talk about ergonomics when it comes to surgical techniques.

Surgical Ergonomics: Pain in HQHVSN vets

So… is there even a problem? Is ergonomics and pain something we need to spend time thinking about in spay-neuter veterinarians?

In order to figure this out, in 2011 I designed an online survey and collected responses from veterinarians who currently or previously perform spay and neuter surgeries at least 4 hours a week. I asked about hand and body pain, and whether that pain affected their work or activities, whether the pain was related to spay/neuter, and whether they had ever had to miss work because of the pain. I also asked about interventions that they had tried in their surgery day as well as outside of surgery, and about job stress and their satisfaction at work.

Here you can see the profile of the 219 people who responded to the survey.

As you can see, there is quite a range in experience and workload, but overall from what I have seen, this population is pretty representative of the population of people working in the spay neuter field.

When I looked at the prevalence of pain, I found that 99% of the vets in this survey had experienced some musculoskeletal discomfort in the past month. 98% had body pain, and just over ¾ had hand or wrist pain. While this sounds really alarming, other surveys of veterinarians in a variety of practice areas have shown nearly as high prevalence of discomfort.

There is a lot of variability in the severity of discomfort that people experience, and the number of body regions that were uncomfortable. Some veterinarians had worked full time for many years in spay neuter with relatively little discomfort, and others are uncomfortable with a much lighter workload.

This diagram shows the body regions where spay neuter veterinarians most commonly experience discomfort. As you can see, the low back, neck, and shoulders are the most likely to be uncomfortable.

Low back pain is common in humans, and so the high proportion of vets reporting low back pain in the past month is actually in line with other surveys of people.

However, the rate of neck, shoulder, and upper back pain is about 40% higher than what is reported in other surveys of veterinarians. The only surveys where I have seen these high rates of neck pain are in human surgeons.

This diagram shows the areas of the hands and wrists where spay neuter veterinarians most commonly experience discomfort.

The right thumb and wrist are the most commonly painful areas– this was true of the lefties that answered as well as the right handed vets.

One big question this research was trying to answer was “what are the workplace factors that contribute to pain?”

Of the work factors, hours per week in surgery (TIME) had the greatest relative importance in predicting total pain score, followed by years in spay neuter (CAREER). Number of surgeries (LOAD) and surgeries per hour (SPEED) were the least important predictors of pain:

TIME > CAREER > SATISFACTION > LOAD > SPEED

However, these workplace factors only explained a small amount of the pain score. Most of the differences would have to be explained by individual variability, genetics, activities outside of work, and other factors that we may not even think about.

Many studies in many fields have shown that people who have higher job stress or lower job satisfaction experience more work-related pain. In this study, nearly every measure of discomfort increased as people had higher stress and lower satisfaction.

We can’t say from this survey that this is a direct cause-and-effect process, although other studies have suggested that it can be. It may be best to think about pain, stress and low job satisfaction as a cycle that feeds on itself.

So as you’re trying to solve ergonomics problems in your workplace, take the time to consider that working on psychosocial issues may actually improve peoples’ physical comfort as well.

This is a basic summary of my study Prevalence and Risk Factors Associated with Musculoskeletal Discomfort in Spay and Neuter Veterinarians. If you are interested in more details and analysis, you can download and read the entire study here http://www.mdpi.com/2076-2615/3/1/85.

In my next post, I’ll talk about some basic things that spay neuter veterinarians can do to improve their physical ergonomics when they set up their surgical space.