finite element analysis of brain injury accidents

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axel_knutt
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Re: finite element analysis of brian injury accidents

Postby axel_knutt » 19 Dec 2016, 12:31pm

Vorpal wrote:They looked at specific injury accidents. In other words, that a a crash had already occurred was a given, so crash rates and risk taking could not otherwise be considered.

But that's the point, they keep producing research that purports to show the benefit of helmets when they're systematically biasing it by presuming that the impact has already taken place.

al_yrpal wrote:Its just common sense, finite element analysis isnt needed for that.

It was common sense that told us the earth is flat and the sun orbits around it.
“I'm not upset that you lied to me, I'm upset that from now on I can't believe you.”
― Friedrich Nietzsche

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pjclinch
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Re: finite element analysis of brian injury accidents

Postby pjclinch » 19 Dec 2016, 12:57pm

al_yrpal wrote:Its just common sense, finite element analysis isnt needed for that. Firemen, construction workers, plant workers, miners, policemen and fighter pilots amongst many others understand it too.


Around half of traumatic brain injury in the UK comes from motor vehicle accidents. So since pretty much nobody drives (or is driven) in the UK with a helmet outside of motor sport, presumably this "common sense" of which you speak isn't shared by the remarkably, errrr, common group in the UK population that travel by motor vehicle. Even though those that also e.g. fight fires, build building etc. are sharp enough to wear PPE at work (unless, that is, they're driving a fire engine at the time, bending the usual traffic rules some when giving it some blue...)

Pete.
Often seen riding a bike around Dundee...

iviehoff
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Re: finite element analysis of brain injury accidents

Postby iviehoff » 19 Dec 2016, 2:15pm

The modelled accidents are only ground/helmet impacts, and have a maximum impact velocity of 7.2m/s (about 17mph). These impact velocities came from a model of cyclists falling off their bike, not any accident data. It does not consider any other kind of accident.

My guess I think that this only covers a fairly narrow range of real world accidents, especially excluding the really serious accidents. This is the danger of interpreting academic papers into real world situations. People will naturally think that they have modelled the full range of typical bicycle accidents, but they have not. People will say "look this shows helmets work", but it doesn't, because the real world of accidents is a lot more complicated than "do bicycle helmets protect against ground impacts". I think the authors have fundamentally misunderstood the criticisms of why people say helmets don't work. I don't think anyone (sensible) disputes that they do not work in this narrow sense.

tomsumner49
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Re: finite element analysis of brain injury accidents

Postby tomsumner49 » 19 Dec 2016, 3:55pm

I'd agree about the danger of extrapolating this to other types of accident - the study only considered 3 specific cases out of 86 with available data and it's not clear to me why they chose those 3.

Stevek76
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Re: finite element analysis of brian injury accidents

Postby Stevek76 » 19 Dec 2016, 4:41pm

Stevek76 wrote:The stand out problem to me is that the three impacts it considers are all largely within a helmet's design parameters.

What about at the speeds where you're actually going to die, and also snagging on vents.


The cynical would suggest they were chosen precisely because of the bold part...

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Wanlock Dod
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Re: finite element analysis of brain injury accidents

Postby Wanlock Dod » 19 Dec 2016, 4:57pm

Personally I don't think that there is much controversy about whether a helmet might provide some protection in the event of an impact, but rather whether or not that protection makes any real difference in terms of cyclist safety, especially for serious injuries.

A man that sells cycle helmets says that cycle helmets work as long as you hit your head. Perhaps not that much of a big deal after all.

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531colin
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Re: finite element analysis of brain injury accidents

Postby 531colin » 19 Dec 2016, 6:28pm

......or helmets work as long as you hit your head in a way that doesn't cause a rotational injury.

Steady rider
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Re: finite element analysis of brain injury accidents

Postby Steady rider » 19 Dec 2016, 7:04pm

Data shows that approximately 93% of head injuries were considered minor, 5% moderate, 2% serious and 1% severe.

They are probably looking at the 2% range and 1% range. The ages of the three people were 61, 65 and 68, they only used 3 cases in their study. Age may have little to do with the results but they were probably not typical of cyclists overall. One of the authors appears to be connected to a helmet company.

A recent report detailed that cyclists wearing helmets had more than twice the odds of suffering an injury than cyclists not wearing helmets, with an OR value 2.81, 95% CL =1.14, 6.94. see Porter AK, Salvo D, Kohl HW, Correlates of Helmet Use Among Recreation and Transportation Bicyclists, AJPM 2016. https://www.ncbi.nlm.nih.gov/pubmed/27866599