If there was ever a learning curve for me in my 32 years of experience with power wheelchairs, it
was in the term seat-to-floor height. |
See, for around the first 15 years of my power wheelchair
use, seat-to-floor heights effectively didn't exist. Sure, every power wheelchair had a literal seat-to-floor
height that is, the distance from the front edge of the seat to the ground but it was fixed, non-variable
by model. If you purchased an Abec power wheelchair, you got whatever single seat-to-floor height it
featured, and the same went for the E&J and Invacare models, as well there was no choice. And, as users,
no matter if our new power wheelchair came with a 17 seat-to-floor height, or one that was 21, we simply
adapted to whatever seat height at which we sat.
However, times changed, and user-specified seat-to-floor
heights came into season, namely due to two trends: A shift toward power base designs in power wheelchairs,
and the popularity of highly-adjustable manual wheelchairs. Conventional power wheelchairs featured the
seat as part of the frame, so because the seat upholstery fastened to the side frames, there was no way
to adjust the seat-to-floor height. However, power base designs where the seat was separate, and sat
atop the power base allowed the seat to be raised and lowered within a range. Then, with manual wheelchair
users discovering that achieving a tailored seat-to-floor height through adjustment could make many aspects
of life easier namely, transfers and table access user-specific seat-to-floor heights began gaining
popularity across the range of mobility products, moving from manual wheelchairs to power wheelchairs.
Today, seat-to-floor heights are arguably an obsession among consumers, clinicians, and manufacturers,
where seat-to-floor heights are specified to the thousandths of an inch, and power wheelchairs are sometimes
chosen by consumers and clinicians almost exclusively based on seat-to floor height potentials.
However, how consequential are seat-to-floor heights, how are they determined, and can one ever take
them too literally?
Seat-to-Floor Height Factors
For starters, seat-to-floor height is a
critical factor in power wheelchair use, dictating the height at which one sits and, as a result, how
one accesses one's environment. An ideal seat-to-floor height allows easier transfers to commodes and
beds alike, and can enhance aspects like windshield visibility when driving a van from a power wheelchair,
or allows one to tuck one's knees under a desk.
However, as one can imagine, there's vast subjectivity
to an ideal seat-to-floor height for any one person or environment. One's bed is usually taller than
one's commode, and one's desk may be a different height than one's dinning table, so compromises sometimes
have to made in selecting a seat-to-floor height that fits in all of one's environments. What's more,
a tall person may require a higher seat-to-floor height than a shorter person specifically so one's
long legrests clear the ground so there's physical subjectivity to an ideal seat-to-floor height, as
well. (And, let us not overlook the fact that a seat cushion increases seat-to-floor height by its compressed
thickness, where a 2 cushion seats one lower than a 4 cushion.)
The goal, then, in selecting
a seat-to-floor height is in balancing one's overall environmental and physical needs, and finding the
number that best serves as an average toward overall functionality.
When a power wheelchair's
seat-to-floor height is specified on an order form, it's measured from the bare seat pan to the ground,
not including the cushion (the exception is captain's type seating that incorporates padding and upholstery).
Adult rehab power wheelchair seat-to-floor heights generally range from 16.625 to 22, varying
by model and seating. For example, on a particular power base, the lowest seat-to-floor height with a
non-powered rehab seat might allow from 16.625 to 20 based on adjustable mounting towers, but a power
lift-and-tilt may start at an 18 seat-to-floor height based on space needed for its mechanisms. Therefore,
while most power bases and seating today offer adjustable seat-to-floor height ranges, it varies by model
and seating. Again, when mixing components, there's often not an ideal, but a balance, where one's seating,
power base, and stature must be balanced to a functional seat-to-floor height.
Then, how does
one establish a seat-to-floor height that will best balance overall functionality? The answer is, by
studying one's uses and environments:
How tall are all of the transfer surfaces that one encounters
At what height does one need to sit to appropriately drive one's van?
Is there any
extraordinary environmental access issue that needs especial consideration, such as fitting under a work
Again, not all environmental factors are at the same height one can't say that a single
seat-to-floor height measurement ideally applies to all factors. However, if one's raised commode is
19 high, one's bed is 24 high, and one finds that an 18 seat-to-floor height would be ideal for driving,
a 20 total seat-to-floor height (which would be a 17 pan height plus 3 of compressed cushion height)
may prove the ideal average of all three surfaces, placing you in a realistic position to access them.
To the contrary, a 16.625 or 22 seat-to-floor pan height would place one outside of all of
the previously-described environmental sweet spots, so it wouldn't make sense to go below or above
one's environmental needs. Therefore, in determining one's meaningful seat-to-floor height, a simple
mathematical equation of adding your environmental surface heights, then dividing by their quantity (as
in, commode + bed + van, divided by 3 = average seat-to-floor height, then factoring in a cushion), makes
for a practical formula to determine a successful seat-to-floor height.
some consumers require an ultra-low or super-tall seat-to-floor height for environmental or physical
reasons, it's important not to assume that extremes are better for a user without full considerations.
For example, there have been clinicians who believe that the lower the seat-to-floor height, the better.
However, while a sub-17 seat-to-floor height may be fine for some transfers and environments, it may
not be ideal for most. For example, I use a 19 seat-to-floor height, with an additional 3 of compressed
cushion, and due to my stature and environment, it serves me ideally. However, if I were seated at an
ultra-low 16.625, I would certainly be very uncomfortable at my kitchen table and desk, couldn't reach
into my sink, and transferring onto my 24-high bed would be a major uphill climb so shorter doesn't
always mean better.
Similarly, some consumers assume that a taller seat-to-floor height is better,
allowing them to reach high objects and look those who are standing more closely in the eyes. Yet, a
super-tall seat-to-floor height can make fitting under desks and tables impossible, as well as make lower-level
transfers very difficult. Therefore, taller is rarely better.
In these ways, rather, than automatically
presuming that an extreme seat-to-floor height shorter or taller is an ideal, clinicians and consumers
should truly consider one's individual needs, then select a fitting measurement.
Another pitfall of seat-to-floor heights to avoid is getting too concerned with decimal differences.
A 17.375 versus a 17.475 seat-to-floor height truly will not impact one's functionality. Yet, clinicians
and consumers have been known to select one seating system over another due to one-tenth of an inch difference
in seat-to-floor height (and some will even use a hundredth or thousandth of an inch as a deciding factor!).
Literally, one's pants thickness or wheelchair tire wear can vary by one-tenth of an inch, so picking
one seat over another based on one-tenth of an inch is really a moot point (and, simply going from flat-free
to pneumatic tires increases a power wheelchair's seat to floor height by three-eighths of an inch
so fretting over one-tenth of an inch in seat-to-floor height proves entirely pointless). One-half inch
in seat-to-floor height may make a difference; however, nitpicking numbers to the tenth, hundredth, or
thousandth of an inch serves no purpose.
The Right Height
Indeed, finding the right seat-to-floor
height of a power wheelchair in relation to a specific individual's needs really comes down to fundamental
-Rehab seat-to-floor heights on order forms are measured from the ground to the bare seat
-The functional seat-to-floor height includes the cushion compressed under the user's weight
(as in, a 17 seat-to-floor height plus a 3 compressed cushion equals a 20 functional seat-to-floor
-Measuring vital transfer heights and other environmental access points, like desk heights,
then averaging their heights can prove a practical method to determine an optimized all-around seat-to-floor
-Avoid extremely low or extremely tall seat-to-floor heights unless necessity dictates
-Don't dwell on measurements within a tenth, hundredth, or thousandth of as inch of each
other, as they become truly inconsequential.
Following these fundamentals will place you in the
sweet spot of sitting, where your transfers won't feel like your plunging into the Grand Canyon or climbing
Published 9/09, Copyright 2009, WheelchairJunkie.com