When Seating & Mobility Components Are Considered
- By Laurie Watanabe
- Feb 01, 2012
Do you ever feel as if the seating & mobility realm is composed of strings of numbers?
There is, for example, a long list of measurements for every client who’s getting fitted for a seating or mobility system. There are seat widths and depths; there are different back heights, seat-to-floor heights and degrees of tilt and recline to consider.
And of course, on the funding side there are diagnosis codes, HCPCS codes and allowables. Those strings of numbers can get particularly long for complex rehab clients, whose systems may be made up of many, many components, each of which needs to be accounted for, listed on the claim form, and justified.
All that itemization makes it easy to see a lot of individual parts and pieces, but perhaps makes it harder to see the seating & mobility system as a whole. It’s an industry version of not being able to see the forest for the trees.
While some members of your business unit do need to concentrate on those individual numbers — for instance, the folks in accounts payable — what happens if ATPs fixate on components rather than the “bigger picture”? And what can happen if ATPs regularly step back to consider the bigger picture as they move through the assessment, product choice and fitting processes?
Everything Is Connected
The old “Dry Bones” spiritual that’s sung to teach anatomy to kids is pretty basic (hey, what about ligaments or tendons?). But its general idea of your knee bone connecting to your thigh bone and your thigh bone connecting to your hip bone does contain a central truth that applies to seating.
“Think of it this way,” explains Sharon Pratt, PT, clinical education director for Sunrise Medical. “The sacrum connects to the spine at S1/L5. The sacrum’s position dictates the rest of the spine reaction. The head is connected to and balances on top of the spine. Therefore, the position of the sacrum and pelvis must be considered when evaluating a person’s trunk stability, head position and overall sitting balance.”
Lois Brown, MPT, ATP, rehab clinical education specialist for Invacare Corp., says, “Cliché, but true: Where the pelvis goes the spine will follow.”
“No matter how you position the person, it all starts at the pelvis,” says Jay Doherty, OTR, ATP/SMS, Quantum Rehab’s clinical education manager. “The pelvis itself directly influences every other part of the body, so if you have a slight obliquity, that’s going to transfer up into the spine as well as into the lower extremities.”
Starting with the Pelvis
Therefore, Doherty says, the pelvis can be considered the starting point for the clinician or provider.
“We always start our positioning down at the pelvis for that reason,”he notes. “An obliquity, a rotation, all of that impacts everything else throughout the entire body.”
Among clients that ATPs can expect to evaluate, Brown says, “Some common postures that can develop are posterior pelvic tilt with a thoracic kyphosis, anterior pelvic tilt with a lumbar lordosis, a pelvic obliquity with a subsequent ‘C’ curve scoliosis or a pelvic rotation and a resultant rotoscoliosis.”
“Everything that happens with the hip/pelvis relationship and the pelvis/spine relationship affects everything related to sitting,” Pratt says. “When the pelvis is in neutral alignment with respect to the sitting world, the spine — assuming there is flexibility — will be in its best alignment for optimal spinal stacking, exhibiting neutral/natural spinal curves.
“When the pelvis is rotated rearward (posterior pelvic tilt), the spine assumes a compensating kyphotic posture with flattened lordosis. And likewise when the pelvis is oriented in an anterior tilted position, the spine assumes a hyperextended-increased lordotic posture, and of course with a lateral pelvic tilted position, we can expect a compensating scoliosis. Given that the head is connected to and tries to balance on top of the spine or remain in a midline position, the head position will also be greatly impacted by what’s happening at the pelvis, hips and spine.”
“Typically, if somebody has even just a slight pelvic obliquity, you can be pretty sure that you’re going to see that transfer up into the spine in some sort of lateral scoliosis,” Doherty says. “It may not be an extreme scoliosis, but there will be some sort of curvature. The natural tendency when we have an obliquity is to right ourselves. We want to right ourselves, keep our shoulders level and our head in midline, so for that reason the two of them are connected, very much so.”
While many seat cushions are designed to offer postural support, they may not be able to offer enough, Brown says.
“The support surface alone is usually insufficient to prevent or minimize these postures,” she explains. “In other words, supporting the posterior aspect of the pelvis, specifically the PSIS or posterior superior iliac spine, provides a key point of control along with a contoured cushion that has a posterior lateral wall to help shift the pelvis toward neutral.
“Without the posterior support, the pelvis and thus the lumbosacral junction can fall into a kyphosis and cause the trunk to collapse. With any of the postural asymmetries mentioned, surface contact is decreased, and pressure on areas of the spine is likely to increase. Thus often the goals in seating include increasing surface contact for achieving a ‘corrected’ posture, minimizing further asymmetry and dispersing pressure over a larger surface area by increasing contact of the back support as well as the cushion.”
Benefits of a Holistic Approach
While the item-by-item, line-by-line explanations and justifications demanded by funding sources do force ATPs to spend a lot of time considering individual components, the clinicians interviewed for this story agreed: There are benefits to considering the whole as well as the parts of a seating & mobility system.
“I believe that the seat support and the back support have to be in harmony — both respecting the goals for overall sitting posture, function and skin protection,” Pratt says. “Whether the two are made together or are separate components ordered at the same or different times, they must work together to provide optimal inferior and posterior support in alignment with gravity and functional goals for the client. If this doesn't happen, the likelihood of poor outcomes is greatly increased.”
A simple example of a poor outcome, says Brown: “Seat depth can be altered by the thickness or depth of the back support and can prevent the individual from sitting back in the seating system, thus creating the risk of a posterior pelvic tilt and secondary complications, such as respiratory compromise, (and difficulties with) swallowing, reaching and visual field.”
One of her clients, Brown says, came in for a pressure mapping session involving a seat cushion. But Brown found “what appeared to be a pelvic obliquity with increased pressures on one ischial tuberosity. The back support was planar without laterals or inherent contour. Correction of her midline posture by adding lateral contour decreased the ischial pressures without changing the seat cushion — the origin was her trunk posture. Again, it’s an example of evaluating the whole seating system.”
Because of the interconnectivity involved, Doherty says, “I don't just look at backrests and seat cushions, necessarily. You have to look at the entire system as a whole. Everything that goes on at the pelvis is going to directly influence the trunk, so I still start down at the pelvis. But when I make a change down at the pelvis, how does it impact the rest of the body? Because I may level the person’s pelvis out, but now the trunk is crooked. So I then have to move back up to the trunk and look at what I have to change.
“That small change may change what goes on at the trunk and what goes on in the lower extremities. It can even impact the person’s ability to use their arms.”
Considering the impact of the seating system on the mobility system can also be beneficial.
“In manual propulsion,” Brown says, “the recommendations are to promote propulsion efficiency with long, smooth strokes. Look at the type of propulsion pattern, but it is also imperative to look at the posterior forces and resultant backward trunk lean that can occur between pushes. Th is can indicate that the back support is not high enough or without enough posterior lateral support to prevent that lean and loss of energy with propulsion.”
In another client’s case, Brown says, “The chair is a titanium ultralight with a heavy fluid cushion. Not only does the cushion increase the total weight of the chair, which is often overlooked, but it also changes the seat-to-floor height of the wheelchair, which affects ‘sitting into the chair’ for stability and the ability to achieve a ‘gear’ on the wheel for manual propulsion. So the weight and height of the cushion, and the contour of the cushion, need to be taken into account.”
Finding the Right Balance
When seat cushions and backs do come together functionally, they can make very positive differences in consumers’ lives.
“The seat cushion and back support together have great impact on propulsion as well as on pressure management,” Pratt says. “A wellfitted back and seat support should maximize surface contact area in all the inferior and posterior aspects of the sitting body where one can tolerate load, and together should respect body shapes and angles in a way that optimizes pelvic/spine and pelvic/hip stability, which will in turn enhance function and pressure distribution in a correctly fitted wheeled mobility base. Equally important throughout this whole discussion, of course, is foot position and loading in the presence of feet.”
Fortunately, seating & mobility manufacturers are lending their support — literally — to the goal of achieving a balance between seats and backs, and the mobility systems that use them.
Says Megan Kutch, MS, OTR, GM of Quantum Rehab applications and clinical development: “I feel that more manufacturers are starting to look at seat cushions and backs together and developing them more as one in order to provide the maximum comfort.
“I know that in future development, Quantum Rehab is looking into the possibility of doing a seating system that will give you the opportunity to pick your seat width and then also pick your back width separately instead of having to do an 18" wide seat width and 18" wide back. We’re looking at incorporating that together down the road.”
ATPs also have their own tried-and-true ways of ensuring they’re getting a good look at the big picture in addition to taking in all the details.
“My evals always started the minute I laid eyes on the person,” Doherty says. “I didn’t necessarily ask how they propelled their chair, but I watched as they propelled into the evaluation room. I might have seen how they transferred out of their car; maybe I was waiting for them at the door, and I saw how they transferred in and out. So I’m gathering all that information right at the very start of the evaluation process.”
And ultimately, Doherty says, clients themselves hold many answers to the question of how they need their seating systems and mobility devices to work as a whole.
“I’ve actually had people opt out of using a seat cushion that may have provided the best envelopment and pressure distribution for that person, but it impacted their function too much,” he remembers. “They opted not to choose that seat cushion. Skin integrity wise, it might have been the best product for them, but it impacted their function too much, and you can’t take function away from somebody who has limited independence already.
“A lot of people come in with a preconceived idea of what they want. What you need to do is be a really good listener. You have to observe and look at how they use their bodies. But the big thing is to be a good listener because they’re going to tell you what they want their system to be able to do. Then you have to look at how you can meet that need.”
This article originally appeared in the February 2012 issue of Mobility Management.