On Their Shoulders

Propulsion Is Often Blamed for Shoulder Pain, But Is that a Fair Assessment?

Shoulder InjuryWheelchair users may often feel that the weight of the world is on their shoulders. And given everything that their shoulders have to accomplish every day, it's an apt metaphor.

Too often, the end result is shoulder pain and injury, which can start off as annoying, but become debilitating.

For ultralightweight wheelchair users, shoulder pain has long been correlated — rightly or wrongly — with long-time self propulsion, to the extent that some ultralight consumers may believe shoulder pain to be inevitable.

But for wheelchair users, is shoulder pain that simple?

The Anatomy of Shoulder Pain

The first step to understanding why shoulder pain occurs is understanding the anatomy of the shoulder itself.

In a 2008 interview with Mobility Management, Margaret Finley, PT, Ph.D., Krannert School of Physical Therapy, University of Indianapolis, said a surgeon she'd worked with likened shoulder anatomy to "a softball on a postage stamp."

"You get a sub-maximal load on your shoulder joint with every push," Finley said, "because (users who self propel) are essentially walking on their hands — and the upper extremity was not designed for that, especially the shoulder, because it really has no bony connection to the body. It's held together with ligaments and tendons."

As a result, says Jay Doherty, OTR, ATP, Quantum Rehab's clinical education manager, "Our shoulder is not designed to be a weightbearing joint. It's designed for mobility and function."

But that situation changes for spinal cord injury patients, Doherty says: "When you lose use of your lower body and you have to use your arms for everything you do, you certainly place a larger risk of developing injury on that joint."

Chris Maurer, MPT, ATP, Shepherd Center, adds, "Anybody with quadriplegia has impaired muscle strength or imbalance" — which can further complicate the situation for an overstressed shoulder.

Identifying Shoulder Stressors

While a wheelchair may often get the blame for shoulder pain, propulsion is hardly the only time a shoulder is given a workout. Maurer points out, "Everyday stressors are anything that's repetitious." That includes, she explains, "reaching overhead to do anything — anything that's got a higher height than where they sit stresses the shoulder. If they're manual wheelchair propellers and they load the chair in and out of the car, that stresses the shoulder."

In fact, shoulders figure prominently in many activities of daily living. Just think about your morning routine, and how much shoulder-related activity is needed to eat breakfast, brush your teeth, shower and get dressed.

For wheelchair users, additional shoulder stress comes in the form of transfers, which typically happen all day long.

Says Doherty: "You get up in the morning, you transfer to your chair. If you go into the bathroom to get ready, maybe you transfer to the toilet first, then back into your chair or maybe directly into the shower. You get out of the shower and transfer into your chair. Maybe you transfer back into our bed to get dressed because it's easier in that location. And that's just the start of our day."

Manual weight shifts also stress the shoulder joints. Push-up weight shifts, Maurer says, "certainly add more of a stress than side-to-side or forward leaning. But depending on who you are and if you have shoulder issues, that might also be stressful." After all, to perform a forwardleaning weight shift, Maurer points out, "You still have to push back up."

Creating Solutions: Seating & Mobility Configurations

Fortunately, today's seating systems and ultralight wheelchairs can be configured to make propulsion as efficient as possible.

"You want to glide more between strokes," Maurer says, adding that ultralight users should strive for long, smooth strokes as opposed to shorter, choppier ones. "Every time you hit the handrim, you're creating force against your shoulder. You want to grab the wheel while it's moving forward. You don't want your hand to be reaching back to grab the wheel and then changing direction."

Proper positioning in the chair is crucial to enabling efficient propulsion, so Doherty suggests, "Make sure that the shoulder is in good alignment with the wheel. If you have somebody leaning off to one side of the chair, they're certainly going to be putting more stress potentially into one of their shoulders because of the position they're in.

"Once you have the person seated correctly, you want to check their arm position in relation to how high they sit within their chair. There's research that shows a good rule of thumb is when you have your hand at the top of the handrim, your elbow should be between 100° and 120°, flexed. So it should have a 100° to 120° angle from your forearm to your upper arm. If the person sits in their chair and they lower their hands down next to the wheel, their fingertips should be at the axle of the chair. That tells you that the user is pretty well set up for propulsion within that chair."

Speaking of positioning: Maurer says some clinicians believe that a client's ability to self propel means manual mobility is the best choice: "‘You're a C6 level injury, you can do your own weight shifts, you don't need a power tilt,'"she says as an example. But she adds: "I sometimes err on the side of caution on that. If they have a C6-level injury, they have impaired shoulder musculature and upper back musculature. Don't take away the ability to do a weight shift that requires no physical effort."

If that client is put into power mobility, Maurer notes, "at least they have a way to do a weight shift if something happens to their shoulders. You're not stressing their shoulders every half an hour, all waking hours of the day just to do a weight shift."

While many clinicians generally prefer to recommend as minimal an amount of assistive technology as possible, Maurer says, "I don't think that's necessarily a good thought process for these people. You see people whose shoulders are so strapped that they can no longer dress themselves, they can no longer transfer themselves, they can no longer do their jobs."

Choosing power mobility, she notes, "might prolong their ability to dress themselves and transfer themselves and do their ADLs by themselves, if you give a little thought to that shoulder preservation. They may not use the power tilt for every weight shift, but it's there for them. If they use it even a little bit, could we improve or delay the shoulder pain and issues that we see?"

Creating Solutions: Transfer & ADL Adjustments

Doherty says when it comes to shoulder pain in wheelchair users, "It's been my experience that transfers a lot of times are a pretty big culprit because you're leaving one surface and going to another. Quite often, someone with a lower-level spinal cord injury will at first use a transfer board. Later on, they may decide they don't need that: They make the direct transfer without the board. So they're lifting themselves up and putting themselves down on the other surface. Some people who have partial leg use can bear a little bit of weight there, but they're still relying on their arms significantly."

He adds, "One of the things I always talked to people about is ‘Can we reduce the number of transfers you perform during the day?'"

"Anything they can do to even out their transfer surfaces is helpful," Maurer says, "instead of getting a bed that's a foot higher than their wheelchair surface. I would say that level transfers are less stressful to their shoulders than un-level transfers."

Paying attention to surfaces throughout the client's home is also important.

"When we're talking about somebody in a wheelchair, even a standard counter can be relatively high for them," Doherty says. "So where are their arms being placed? Are there surfaces in their home that may be able to be changed?"

Maurer also recommends examining techniques when reaching: "Making sure that you use your chair properly, such as securing wheel locks when you're trying to reach, rather than fighting your chair rolling back when you're reaching. It's easy and quick to not have to take this extra step, but depending on where you are and how you're reaching, you might be fighting the stability of your chair."

Propulsion As Part of the Equation

Of course, propulsion remains part of any discussion of shoulder pain and injury. Both Maurer and Doherty cited Paralyzed Veterans of America clinical practice guidelines that discuss shoulder injury and protection — titled "Preservation of Upper Limb Function Following Spinal Cord Injury," the pdf download is available free at pva.org.

"One of the things they talk about," Doherty says, "is getting the axle as far forward as possible for individuals, but of course, you also have to look at their wheelchair skill level and make sure they're not going to tip over backward constantly. So they can have a longer wheelchair propulsion stroke, and keep their hand on the handrim as long as they can to reduce the number of push strokes that's required to go a set distance."

Maurer says that while the overall weight of the ultralightweight chair is important to consider, the chair's components should also be scrutinized: "The weight of the wheels impacts how hard it is to push, not necessarily the weight of the chair. It's the weight of the wheels, as well as the tire type. Pneumatic is the most efficient, and bigger casters are easier to push than smaller casters. There's a trade-off: Smaller casters turn a little bit easier than bigger casters. But as far as ease of propulsion, the bigger the wheel, the easier to push, the less rolling resistance."

She adds that discussions about propulsion stroke styles — figure-8s versus loops, etc. — may be "a little misinterpreted. You change your stroke depending on what surface you're on. How you push your chair on a flat surface is different from how you go up a hill. If you're going up a hill, you are going to do shorter, choppier strokes, and you're not going to drop your arms down and around because you'll roll back down the hill. You can do any stroke you want, as long as you do smooth, long strokes. That's what's been shown to be the most effective."

As for the common belief that propelling a chair inevitably leads to shoulder pain and injury down the road, Maurer suggests some of the conclusions drawn from research on the subject "go a couple of steps too far... They make conclusions that their data doesn't represent. A lot of wheelchair users have shoulder problems, but we don't know if it's because they push their wheelchairs all the time or if they're doing transfers with their arms all day long. That adds up."

She points out, "With these wheelchair users, that's a constant: They're pushing their chairs. Not everybody who pushes a chair gets shoulder pain. Maybe that's not the issue. Maybe it's because a certain sector is pulling themselves into a pickup truck 20 times a day, and it's the transfers that are leading to shoulder injuries.

"I know people who have been pushing chairs forever and don't have shoulder problems, and I know (people) that do. The chair's the constant. Is it the ADLs? Is it the transfers? Is it that we don't pay for home accommodations in the U.S., so we have to deal with the fact that the counters are way too high for them, or ‘I can't get to a table, so I have to turn sideways to eat all the time'? There's no one answer."

This article originally appeared in the SCI Handbook September 2011 issue of Mobility Management.

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