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Thread: In 2008 VA test, Titanium chairs did poorly!

  1. #1

    In 2008 VA test, Titanium chairs did poorly!

    "The manufacturer’s suggested retail price of the Invacare Top End was $3,218, Invacare A4 was $2,875, Quickie Ti was $2,995, and TiLite ZRA was $2,695. These prices were for the wheelchair configurations tested in this study. The Invacare A4 had the highest value and the TiLite ZRA had the lowest value (Table 4), but no significant differences were found among the four models."

    "This group of titanium wheelchairs survived fewer ECs (their average EC was 246,506 ± 154,086) than was previously reported for aluminum ultralight wheelchairs, but their life expectancy was similar to that of steel light-weight wheelchairs [2–3]. Besides, the titanium rigid-frame wheelchairs exhibited less value than the aluminum ultralight and the steel lightweight wheelchairs (Figure 8)."

    This group of rigid-frame titanium wheelchairs is widely prescribed. Their highly adjustable rear-wheel axles, ultralight weight, and compact dimensions help decrease physical stress on the user when propelling a wheelchair and increase ease of use. This study revealed important design concerns that need to be addressed. Our results should remind manufactures and designers that each weld point, screw hole, and change in structure and frame design has its impact on the strength and durability of the wheelchair. Our results indicate that manufacturers may need to perform more careful analyses before commercializing new products."

    Full report attached.
    Last edited by chasmengr; 07-18-2011 at 09:19 AM.

  2. #2
    This has been discussed in the past and as I recall was pointed out in a few areas where the test was a bit flawed, as I recall, not using apples-to-apples chairs. Do a search in the archives. One thing is for certain, there are a lot of people on these forums using Ti chairs, not to mention thousands sold yearly, and if there was a major issue, we'd know.
    C5-6 Complete - 8/13/1982

  3. #3
    Senior Member Skogy's Avatar
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    Mar 2010
    S. Minnesota
    I wonder how many ultra-light wheelchairs the VA could have bought the deserving veterens instead of spending the money on these tests?

    If the injured vet wants Ti, give him/her Ti. If they want AL give em AL and so on.........

    Our results indicate that manufacturers may need to perform more careful analyses before commercializing new products
    I would love to see their design AND how much they can produce it for, government thugs......

  4. #4
    agreed...i havent see any best comparison yet, only marvel give out the best.but then again, other than cost, i dont see any flaws on using titanium as a wheelchair...dont give a bike as an example.we're not running constant 20mph an hour...
    walking is OVER-RATED!!!

    Broken in August 14th, 2003. T9-L1 complete.

  5. #5

    Be Careful When Drawing Conclusions About These Results

    I cringed when the results of this study were presented at the 2009 International Seating Symposium because I could envision 3rd party payers potentially using it to deny requests for titanium chairs. First, however, I feel some clarification is in order..
    Labeling it a "VA Test" is not entirely accurate. That implies that it was the VA that came to the conclusions in the study--not the individual authors.

    The study was primarily conducted by a graduate student at the Human Engineering Research Laboratory (HERL) in Pittsburgh. Researchers from HERL have made substantial contributions to advancements in wheelchair-related technology and standards over the years. I should also note that a major reason that ultralightweight wheelchairs are now funded by third-party payers is a direct result of HERL's research. While HERL receives VA funding and the Journal of Rehabilitation Research & Development happens to be a VA-sponsored research publication, this particular study represents only one of many research studies taking place at HERL, and the VA had no direct involvement in the study or its findings.
    That said, it is easy to draw misleading conclusions from the study itself without carefully looking at the details. My major issue is the statement...

    Titanium wheelchairs are expected to increase mobility and efficiency in daily living. However, the general features do not endorse this group of titanium wheelchairs as the best choice for manual wheelchair users.
    As Brianm mentioned, one must consider that this was not an "apples to apples" comparison--especially on the double drum test (DDT).

    It shouldn't be a surprise that folding frame chairs with 8" casters will hold up better than a titanium rigid frame with 3" rollerblade style casters on the DDT. The 8" casters will transmit less of the impact to the frame and much of that energy will be absorbed by the flex in the cross brace and seat rails.

    One of the cheapest chairs out there, the Guardian Escort, did very well on the DDT because there was so much slop in the design that most of the energy got dispersed. That chair became the standard "stock wheelchair" in the VA for several years. I have yet to see any VA therapist who was sad to see it go because the very same qualities that allowed it to excel on the DDT made it extremely hard to push. Much of the energy from each push was absorbed by the chair instead of being transmitted into motion. Since they are designed to transmit the end user's energy into motion as efficiently as possible, titanium rigid frames are penalized on the DDT by this lack of energy absorbing slop.

    With respect to the cantilevered frame models, I still have yet to see or hear of any titanium cantilevered frame chair failing at the bend. I think this is because in the real world, these chairs tend to be used by end users who know to keep the amount of weight over the front casters to a minimum. End users who haven't done this (or can not for stability reasons) probably use something other than a 3" rollerblade caster. If their chair was originally ordered with 3" rollerblades, they would probably switch after discovering their chair was endo prone over sidewalk cracks or experienced difficulty keeping their feet on the footrest due to energy from minor impacts being transmitted up the frame.

    Under the testing conditions, it is no surprise where they failed (at the first or second screw holes for the upholstery) or that the ZRa's failed sooner (the screw hole for the upholstery is closer to the bend because of the shorter frame).

    If we set aside the question of whether or not the DDT replicates real world use of this category of wheelchair, there are some interesting questions to consider if these tests were to be conducted under truly apples to apples conditions...
    - Would cantilevered frames with tension adjustable by straps seat upholstery still fail at the bend?

    - Would cantilevered frames still fail at the bend if a 4" or 5" soft roll caster were used instead of a 3" rollerblade?

    - If everything else were equal, would an aluminum cantilevered frame model last longer than it's titanium counterpart (thus representing the better value)?
    My thoughts regarding these questions are that the answers are either "No" or "probably not".

    A significant limitation to the study was that they eliminated the Curb Drop Test if the chair failed the DDT. On these cantilevered frame models, I have more concerns about failure occurring at the camber tube clamp or the backrest hinge when jumping curbs than I have with potential failure at the bend for the front frame.

    Hopefully, someone at HERL or some other setting with ANSI/RESNA testing equipment is doing research into these questions. Those answers have more real-world implications for manufacturers, clinicians, and end users.
    Last edited by SCI_OTR; 07-03-2010 at 04:20 PM.

  6. #6
    Quote Originally Posted by Skogy View Post
    I wonder how many ultra-light wheelchairs the VA could have bought the deserving veterens instead of spending the money on these tests?

    If the injured vet wants Ti, give him/her Ti. If they want AL give em AL and so on.........

    I would love to see their design AND how much they can produce it for, government thugs......

    In a few weeks, I will be posting my first ZRA S2 which is currently on order for one of my veterans. Your ZRA S2 is a very nice chair, but I bet you will drool over his chair when I post it (I know I will). Truth is, I can spec out much better equipment for the veterans I serve than I ever could hope to get for myself (VA employees have private insurance).

    I think you will be less-worried about veterans not getting the equipment they deserve.

  7. #7
    Thank you, SCI OTR. that really adds perspective!

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