Friends broken knee walker research

[StillLearniingInPerth]

Hi there,

I had a friend approach me for a bit of help since I just started studying engineering (1st Year). But I'm a bit overwhelmed where to start and any guidance would be much appreciated. They would like to look into it as much as possible before incurring or wasting lawyer fee's etc.

They hired one of those knee walkers after ankle surgery, but the seat broke off after a few weeks while in use, falling over and re-fracturing the same ankle. it was a Drive 790 Knee Walker rated to 130kg - they weigh 90kg. the break was at the exact point where the seat cross-member is welded onto the vertical pole along with a thin bracket. They are wanting to look into whether the knee walker was poorly designed since the seat is offset on the pole in the L-R direction and has been superseded by another model (796) which does not have this same seat offset.
some pics are below.
[URL unfurl="true"]https://res.cloudinary.com/engineering-com/image/upload/v1639452176/tips/20211214_111954_BRN3C2AF4F5A657_010917_ile7kd.pdf[/url]

Is there anywhere I can look to find design standards for medical equipment, or how would I go ahead working out whether the seat was fit for purpose enough to help them decide if it's worth incurring legal fees or just chalking it up to an unfortunate accident

many thanks

 

[IRstuff]

Personally, I think it's a waste of time. A design flaw would break sufficiently often that you'd be able to find evidence of that in the news. You've all made an assumption that the walker was already damaged through abuse by previous renters, which is just a poor assumption; there are lots of people that don't follow rules and don't care if they damage something that they don't own and therefore have no responsibility for.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!

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[3DDave]

If by "hired" you mean "rented" then it's possible it was damaged in previous service. You'll need to look into Australian laws about medical equipment and liability.

Where did it break? The PDF looks OK.

The following site suggests there was a knee pad post design change -

https://advancedhealthmart.com/prod...dv8-steerable-knee-walker?variant=55920820248

but I don't know if it applies to your case or what the design change was for.

A comment on this video complains of similar problems to yours:

https://www.youtube.com/watch?v=Z1W7sILU4Lg

I don't see a recall for it, so I don't think there's a widespread problem; it appears to be a very popular item so they have likely made in the hundreds of thousands of them.

This may help:

https://www.resna.org/at-standards

 

[StillLearniingInPerth]

IRstuff - appreciate your point of view that regular breakages would have made the news and agree - came here since I was unable to find anything from reputable sources to confirm this is the case. But on first look it does not seem that it would be a strong joint, I'm no welder, so can't speak for the appropriateness of the welds and have not gotten far enough to attempt calculating the tensile strength of the joints/materials. would this be something worth working out for them?

3DDave - Thanks for looking into it, I could not see a recall either but do you read anything into the followup model being so different? I'm not going to look into the laws, a lawyer can do that if they go that route - I am just trying to help them decide if it 'may' be worth splashing the unholy cash on a lawyer. NB. they already made an inquiry and the answer was 'pay for us to send ask our engineer but we have no idea till he responds'
yes it was rented, when it broke the supplier took it away, it broke along the red line shown below

 

[3DDave]

If you no longer have the device, I'd think you have no evidence. If you don't even have a picture then it's all over.

I'm betting on some amount of abuse so the maker is out and if the rental agency took it your options to go after them are probably done as well as you now need them to say "Sure, it was defective, take our money."