SCUBA DIVERS: ISTOCKPHOTO.COM/ORLA
Picture two scuba divers. The first is a strong swimmer, naturally proficient and comfortable in the water. Mastering buoyancy and communicating via hand signals come easily. The second diver is not as comfortable in the water and is not a natural swimmer. To compensate, this diver works hard to get the most from his equipment. He learns to manage his buoyancy control device well and becomes an expert on every bit of equipment used during diving. In this way, he becomes a skilled, efficient diver.
Permobil VP of Marketing Josh Anderson offered that analogy when asked the differences between spinal cord injury (SCI) clients with quadriplegia versus paraplegia. Anderson, who sustained an incomplete injury at the C5-6 level as a teenager, speaks from experience when he talks of optimal setups for ultralightweight manual chairs.
“There are functional limitations,” he acknowledges of clients with lower cervical injuries. “I think [for clients] in a manual chair and having a higher-level injury, the importance of customization related to function becomes that much more pronounced. I think that’s such a big thing.”
Results of Cervical Injuries
When working with clients with SCI in the C5-C8 region, your first thought might be functional limitations in clients’ hands and arms. But the exact nature of those limitations vary from client to client, even if their injuries are in the same range.
For example, Brad Ramage, a Sunrise Medical account manager, has an incomplete C7-8 injury. “I have [use of] my biceps and my triceps,” he said. “I happen to have full extensors, so I can open my hands.” Clients with injuries in the C5-6 area might be able to raise their arms and elbows and flex their wrists, but might not be able to open their hands to use their fingers — a crucial consideration for how an ultralightweight chair will be propelled.
“Higher quadriplegics, like a C6-7, might push with an open palm and put their hands the whole way over the tire and the handrim to get a good friction surface,” Ramage explained.
Compromised function of the upper extremities isn’t the only result of a lower-cervical injury, however. Seated balance can also be a challenge.
“With a higher spinal cord injury,” Ramage said, “you’re usually going to sit with a little bit of posterior pelvic tilt. [These clients] are going to need to be in more of a crunch position, more of a seat angle so you can maintain trunk balance. I use 3.5″ of difference between front and rear seat-to-floor height. My back angle is just slightly open; it’s probably at about 93°, so it’s pretty straight. I try to lock my pelvis out so it gives me that trunk control.”
Seating: Balance & Control
Ramage’s comments touched on an important factor in determining the success of manual mobility for this client population: seated balance and control.
“I think as I’ve aged, my posture has changed,” he said, “and I need to adjust slightly. For instance, I use a solid backrest; I use a JAY J3 low thoracic back with a 9.5″ height. The shell is 9″ tall, but it’s set off of the seat rail so from the top of the backrest down to the seat, the measurement is about 13″. It’s about 4″ from the seat rail to the bottom of the shell.
“I’ve used different types of foam supports inside my back as my posture’s changed, just to accommodate the changes. You’ve got to watch your skin on the back and keep it protected. I’ve noticed some people are migrating to adjustable tension [backs], especially if they have to dress in their chair and they like to extend over the top. A lot of higher-level cervical injuries will use adjustable tension upholstery to allow themselves to sink back in between the back canes, and that way, it almost acts like a trunk support or a lateral support.”
Anderson closes his back angle “because what really feels good for my back is when I’m able to extend over the top of the back a little bit so I get a little bit of lordosis in my lower spine. It gives me a little bit better balance. That works really well for me.
“The back height on my chair is about 13.5″. It’s actually a pretty normal height, just looking at the average height on orders that come through our facility. But it’s very low considering how tall I am [Anderson is 6’9″]. It’s quite uncomfortable for me to have something touching my back up higher; I’m just not used to it. And I like to have [the backrest] end in my mid to lower back so I can curve up over the shelf. It helps with my balance.”
He also uses “an Ergonomic Seat; I love it because it allows me to only move forward so far. I don’t have a lot of trunk control, and as you’re moving, you tend to move around in the chair. The seat keeps me from moving forward too much and having to stop to reposition.”
“Stability creates performance,” said Jim Black, Invacare’s Director of Product Management & Marketing, on the importance of a good seated foundation. Black was 19 when he sustained a spinal cord injury that resulted in paraplegia. “What tends to happen with a bad fit is because of weaknesses, people tend to slide into balance. Their pelvis will slide forward, and when your pelvis slides forward, your head follows so you create that kyphotic posture. That’s how you’re creating balance, how you’re increasing your center of mass.
“If you put 2″ of extra width [into the seat] to fit a coat in for the winter, if somebody is weak, they’ll slide on that weak side because they have space. They’re going to use that space to slide, and that in turn will cause scoliosis or a posture of somebody dipping down. We think of a chair’s center of gravity as the wheels, but the center of gravity is your backrest and the relationship to where your wheels are. When I move my backrest forward and back, that’s really my balance point. So we need to understand where those points are to create a more efficient balance and stability.”
Kim Davis, MSPT, ATP, Clinical Rehab Manager for Sunrise Medical’s northeast region, said she remembers a metaphor that Ramage told her about seating: “I don’t know if he’s the original author, but what Brad told me for folks who are getting ultralightweight rigid chairs — especially who are more at his injury level — is ‘You need to fit the chair like a ski boot.’ It has to be an extension [of the person]. You don’t want slop with your foot to your ski boot; you’re not going to turn effectively. That’s one of the best lessons I’ve learned from Brad about not going too wide [with the seat] and how the chair is an extension of your body. Trunk rotation causes the chair to move, if your hips aren’t slopping around in your chair.”
Weight Distribution: The Best Equation
Another critical aspect to successful self propulsion is the efficient distribution of body weight, which can affect how easily and effectively the wheelchair can be propelled.
“I think I’m using a little more aggressive center of gravity,” Anderson said of his setup, “because as I’m getting older, I can’t sit up as straight as I used to. So I keep the chair very light on the front. I try to run 80 percent of my weight over the rear wheels, and I do that so the chair’s very maneuverable. I’m not front loading the casters. I actually bought pads that are used for balancing cars to balance the weight of the chair so there’s 75 to 80 percent of my weight over the rear wheels.”
Anderson emphasized that such fine-tuning — even involving what seem to be very minimal adjustments — can make an enormous difference.
“If there is an audience that benefits from really fine-tuning the chair, it’s individuals that have upper-body weakness, whether it’s just in their arms or in their trunk. Calibrating to that fine detail, a quarter of an inch forward or rearward for the center of gravity, is a big deal. It’s only a small percentage of weight difference, transferring weight front to rear, but you’re talking about somebody who’s got compromised strength. If that front end is just a little bit lighter but still stable enough that I don’t feel I’m going to flip over backwards, then it makes a huge difference in my ability to turn the chair. It makes a big difference that I don’t need to have camber, so I can fit through a really narrow doorway if I’m in Europe or in Asia in particular.”
“A rule of thumb,” Black said, “would be that 80 percent of the weight be over those axles. When you put weight over the axle, you create better wheel access. Any time I move that wheel further behind me, it starts putting more forces on the front of the chair, and when the front of the chair has more forces and is front loaded, that’s when we create problems with people flipping forward. It stops the rolling dynamics of the product, and it’s unsafe.
“When people start having problems leaning forward, they actually lose a lot of rolling dynamics, so they tend to stay back in their chair. They tend to slide back into posterior pelvic tilt to create that length, so it also affects your seating and positioning. All of these things happen when you’re not balanced over that wheel.”
In the 1990s, Black recalled, “the trend was having these short chairs, short wheelbases, so you had a shorter turning radius. But we found that your only room for defense is to move your wheels back, which takes the wheels away from you and creates more bad postures of people sliding into posterior pelvic tilt. We figured out that when you start balancing that wheel over the top of the body, what happens is now it doesn’t matter how long your chair is. If I can move my wheel 3″ forward, I can grow the front of my chair 3″ more. For every inch, you take forces off that front end. That’s a good thing.”
Like Anderson, Black also believes in balancing a wheelchair the way a racecar is balanced.
“The closer you can get the chair’s center of mass to the user’s center of mass, the more successes you’re going to have,” he said. “Then when you extend that wheelbase to create that stability, it’s really going to make you more efficient. So the trend now is to have longer chairs in the front, moving that wheel underneath you to create a more efficient rolling dynamic for a product. “The most important thing for any manual chair is the fit of the product. The wheel access, the balance and stability create a better-performing product. When you get injured, the first year that you’re in a chair, you’re going to slide into balance. So you might as well create balance off the bat. If you can create balance for somebody, you’re going to fix a lot of seating needs.”
Hand Placement: Optimizing Each Push
Efficient propulsion also depends on the interaction between the client’s hands and the chair’s handrims. Wheelchair users with quadriplegia might be unable to grip a handrim in the same way that someone with paraplegia can.
“My handrims are a big deal,” Anderson said. “I use Q-Grips, Neoprene-coated handrims. They’re not vinyl or plastic, and they’re much more tactile. As somebody who pushes off of friction, I think they’re fantastic. I get a great deal of friction from the handrims.”
Anderson said the Neoprene coating doesn’t build up heat the way vinyl can, particularly when going downhill. “When they get wet, I still have good tactile feel to them; vinyl just becomes like glass. Plus, durability is important. I literally change chairs and keep the same wheels and handrims because my mind has gotten used to every little nick and scratch in the Neoprene, yet they don’t get damaged to where they’re unusable.”
“For somebody who has weakness and limited hand function,” Black said, “the most important thing is to get that wheel even more aggressive and in the right position early on in their disability so they can get the wheel to start rotating. If you can get the wheel to start rotating, then you settle into your balance.”
As for positioning the client’s hand, “The palm of their hand would hit the middle of the hub, where a para’s fingertips would hit the middle of the hub. That’s how much lower we have to get [clients with quadriplegia] into the wheel so they can get the contact point to get their shoulder rocked, to get the wheel to start up and start moving.”
“I use a Q-Grip friction-coated handrim,” Ramage said. “I use an open thumb, and I have my handrims moved in closer, so I can wedge my thumb between my handrim and my wheel. A para’s going to be able to grip the handrim a little bit better than what I can. But if you have less hand function, you’re probably not going to be able to open your thumb as much as I can, so you might have to use more of your palm. Friction coating, rubber coating, plastic coating is what I need, specifically the Q-Grip.”
Transfers: Choosing a Height to Work With
Keeping seat-to-floor heights low on ultralight chairs can be helpful for both accessibility and transferring.
“The way I set my chair up is similar to what a para would,” Ramage said, “because I have my triceps. I can transfer independently; I can get in and out of the vehicle, I can transfer to different surfaces independently. I think that’s a little bit different from someone with a higher injury, say C6-7, who has limited hand function.”
“I would say that just as much of a disability in many cases is my height,” Anderson noted. “It’s not that I’m tall, it’s that I’m really tall. So if I were 6′ or 6’2″, yes, that’s tall. But when you’re 6’9″, if I had a normal front seat height on my chair, I’d have to be somewhere around 23″ or 24″. Because I do have some sensation in my lower extremities, because I gradually swept my legs back [under his seat] over the years, I’m able to sit at a normal front seat height, which allows me to get underneath a table. What a huge advantage that is, just in terms of being able to have a normal conversation with somebody at a meeting or at dinner. With compromised hand function, if you have to sit sideways to the table and then try to eat, it would make everything even that much more difficult.”
Anderson also transfers in and out of his car independently, a fact facilitated by maintaining a relatively low seat-to-floor height: “Since I do drive a car, my front seat height is at 19-20″. If I had it at 23″, that’s another 3″ that I have to go up to get into my chair. It’s another 3″ that I have to accommodate between my chair and my bed, my chair and my shower chair. All of those things can be modified, but there are things that can’t be modified. You can’t modify an airplane seat. It would have made a lot of transfers difficult, whereas now, everything is pretty good for me in terms of being close enough to my chair height that I can get in and out independently. It’s within 3″, and that’s good enough. If you’ve got balance [difficulties] and you’re having to move up 6″ to 7″ into your chair from another [surface], it’s much more difficult. You’re having to accommodate that distance and control your balance.”
Ergonomics: Bring on the Options
While options such as ergonomic handrims and power-assist systems aren’t designed specifically and exclusively for use by clients with quadriplegia, using them can give this population a very helpful technological boost.
Power-assist devices are often considered for self-propellers who experience shoulder or arm pain. Davis said, “I don’t necessarily think of it only for someone who is aging.” But she did point out a reimbursement challenge: “One of the limitations of our funding structure is that Medicare requires that the person has been using [an optimally configured self-propelled] manual wheelchair at least a year before they can be considered for a power add-on — whereas they could be considered for a traditional power chair right from the get-go. So that’s something that our funding structure limits: You can’t consider [power assist] as your first power mobility option.”
Davis said that policy doesn’t extend to some other payors, such as Veterans Affairs, “and Medicaid can be more open. It’s just that when insurance payors decide they’re going to follow suit with Medicare, you have more of a struggle. Medicaid has a federally mandated community-access component to their rules, so you have a much easier chance to argue [power assist] for someone who has Medicaid only.”
Aftermarket performance products can also make propulsion more effective. Consider tire choice, for instance.
“I like to use a high-pressure tire, like the Marathon tire, because it has reduced rolling resistance,” Ramage said. “That really makes a difference versus using a solid insert or something that doesn’t roll as easily. A solid insert can absorb a lot of energy in propulsion. I try to make it as easy to propel as possible.”
“As a wheelchair user,” Anderson said, “you’ve got to take care of your equipment. Keep it clean, keep your wheel locks adjusted. Inflate your tires. The biggest thing you can do is keep your tires inflated. Pneumatic tires are proven to ride smoother than solid tires. Even the best solid tire doesn’t roll nearly as well as a pneumatic.”
“Wheel size has a lot to do with it, too,” Black said. “Obviously, a smaller wheel, like a 24″ wheel, is easier to get rotating. A wheel that is lighter on the outside is easier to get rotating. Those things are important to somebody with that type of disability [quadriplegia].”
Clients on a Roll
Every client with quadriplegia is different, even if their injuries appear similar on paper. Davis said that’s one of the reasons she has learned so much from her clients.
“I’ve been a therapist for over 30 years,” she noted, “and most of us that have been around that long didn’t learn a whole lot about this in school. If we did learn wheelchair setup in school, we’ve come to understand that what we learned was mostly wrong. Such as, ‘Add an inch to each side of the hip.’ Most of the time, it’s wrong to add in a lot of space. You may have to rethink what you learned it in school. So, learn from your expert users.”
Davis also advocates for the right intervention, right away: an optimized seating and mobility system from the very start.
“You want to get them into a good seating clinic right from the get-go so their posture is optimized,” she explained. “It’s a lot harder if, over quite a long period of time, somebody has already learned their trunk balance, with their postural stability in a severe posterior tilt. It’s harder to get them out of it and try to change their posture later on down the line. I would want to offer [manual mobility] first and get them configured correctly so they’re set up to do that optimally, then continue to be able to offer that choice of manual versus power.”