Sunday, 27 September 2015

Safety mechanisms

Seat belts.  Helmets.  Gun safeties.  Shoulder harnesses.  Shut-off valves.  Dead-man switches.  Fire extinguishers.

What do all of these things have in common?  1) They were all designed to save your life in an emergency, 2) They were all added to the safety arsenal as an afterthought when someone realised they were necessary, 3) They work when used properly.

I understand that last one may seem obvious, but stay with me here.  I'm going somewhere with this.

Pneumatic nail guns are wonderful inventions that make construction jobs infinitely easier (not to mention a hell of a lot of fun).

Wait wait wait, nail guns?  What the hell are you on about, Doc?

Yeah, you didn't see that coming, did you?  You thought this was going to be another seat belt or motorcycle story, didn't you?  Listen, I told you to stay with me.  Just think for a second - trauma, nail guns, safety . . . you better believe a good picture is coming.  So be patient.  Or just skip to the end if you want to act like an impatient child.

As I was saying, banging nails with a regular hammer all day runs the risk of repetitive stress injuries, not to mention smashing your thumb (we've all been there) and cursing in front of children who just want to "help" you build them a bird house.  Nail guns eliminate those risks, but they introduce new, even riskier risks, namely firing a sharp weapon somewhere into your body.

To counter that risk, every nail gun (except the ones that fire tiny nearly-harmless pin nails) has a safety mechanism built in to the nose so that the gun must be pressed against a hard surface with relatively significant force for it to fire.  If you're wondering how I know this, I own five of them, including a framing nailer, an angled finish nailer, a straight finish nailer, a stapler, and a pin nailer.  I love my tools.

But I digress.

Joe (not his real name™) was one of those people who didn't seem to think the safety mechanism on his nail gun mattered.  He was completing a frame on a house using a large framing nailer when there was an . . . incident.  An accident.  Well, something happened.  I can't say exactly what that "something" was, because Joe wouldn't tell me.  I'm not sure if it was because he was too embarrassed or because he was screaming in pain.

When he was rolled in, he was fully dressed and clearly in agony.  Most patients who come my way are at least partially disrobed so the medics can assess the extent of their injuries.  Not Joe.  The medics mentioned that because of an "apparent leg injury" they tried to remove his pants, but they wouldn't come off.  And every time they pulled, Joe yelped even louder.

As he was lying there on the stretcher, his leg looked fine.  No blood, no weird angulation from a bad fracture.  But when he rolled to the side so we could see the back of his leg, the problem suddenly became glaringly obvious.

If you're wondering why he was screaming, maybe this X-ray of his knee will satisfy your curiosity:
If you can't tell, that's a 9cm (3.5 inch) clipped-head framing nail that went into the back of his knee, through his femur, and into his patella (kneecap).  It was embedded so deeply and so thoroughly into the bone that the head of the nail had dragged the fabric of his pants at least 1 cm under the surface of his skin, pinning his pants to his leg quite effectively.  

Yes indeed, he had used one of these:

to fire one of these:

into the back of his knee.  Just to give you an idea of how big these framing nailers are, well, a picture is worth a thousand words:

They are HUGE.  And notice the nose of the gun being pressed into the wood?  That's the safety mechanism that all these guns have.  Well, almost all of them.  That nose didn't exist on Joe's gun, because he had removed it.

No, I did not ask him why. 

I still have no idea how he shot himself in the back of the knee, and he repeatedly insisted that there was no one around him and that he did this to himself by accident.  Regardless, the orthopaedic surgeon took him to the operating theatre and had to use various metallic instruments of death and destruction to remove the nail from his femur and patella.  A few days later, Joe walked out of the hospital, still insisting that he did this himself.  Somehow.

So now think back to all the safety mechanisms I mentioned at the beginning.  What else do those things have in common?  They only work IF YOU USE THEM.

52 comments:

  1. I've heard of people shooting themselves in the FRONT of the leg, particularly the thigh, but how do you accidentally shoot yourself in the BACK of the leg with it?

    but here, the stunt almost more popular as disabling the safety on your nail gun is disabling the safety on your circular saw - and as a young man I had a carpenter tell me the story of a guy he worked with for a very short time, who started his employ by disabling the guard on his saw, and then resting the saw on his leg. he also ended his employ by disabling the guard on the saw and resting the saw on his leg. a SECOND time. Right after getting released to go to work after healing from the FIRST time.

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  2. Is his kneecap badly dislocated or is that a side-view of his leg?

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    1. Side view. The view from the front was not as dramatic.

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  3. Most professional construction workers I've met have removed this safety mechanism because apparently you are able to work significantly faster and more effortless if you don't have to press hard every time you fire a nail. They claim they know what they are doing and probably nothing happens for hundreds of thousands of nails they use. Until it does.

    I think for this particular safety mechanism, it needs some work. If it is seemingly that much of a hassle for the folks using it, they should find one that people will actually use. Like seat belts: they aren't in the way, they don't make it harder to drive, and using them only costs a couple of seconds extra. And at least where I live, almost all people use them.

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    1. I don't find them a hassle at all, after the thousands of nails I've fired. Never have I thought "Damn this stupid safety feature that the manufacturer put there (and is likely legally required) to protect me!"

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    2. having used both a framing nailer and a siding nailer, I can say for a fact you have to press hard whenever you fire a nail, or go back and hand drive a whole bunch of poorly driven nails. and usually, the weight of the gun on the material presses the safety back just fine. once in a great while there will be a bit of challenge nailing in an awkward corner, but I would be inclined to say anyone who says disabling the safety makes the gun work better is speaking from prejudice instead of experience.

      and probably doesn't wear a seat belt, either.

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    3. I can't imagine this. I don't have a lot of experience with pneumatic nail guns but in my experience the safety needs less pressure to activate than you need to apply to get a good nail anyway. Maybe it's different for the larger guns, though.

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    4. Accidents can happen even with safety mechanisms. See below:

      https://www.youtube.com/watch?v=qY0-5oU4POE

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    5. @Loren: it's not. even with the heavier gun. not holding it tightly against the material will result in a nail standing proud.

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    6. @anon: yes, getting in the habit of carrying the nailgun with your finger on the trigger is as dumb as removing the safety.

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  4. I think you're find that it all makes sense how he accidentally shot himself in the back of the knee if you replace it with his friend who he's covering for accidentally shot him in the back of the knee...

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    1. There's another possibility too. Maybe he was trying to scratch a pesky itch, or shoo away a stinging insect, and reflexively used his dominant hand to do that...which would also be the one holding the nail gun.

      In the process of reaching down and behind his body, with his hand holding the heavy tool, his finger may have accidentally pressed the trigger, so, with the safety disabled, there goes the huge nail. If he happened to be standing on a ladder while working on this particular section of framing, he may have also been struggling a bit to keep his balance *and* hold on to the nail gun while doing so, which would make the accidental trigger squeeze even *more* likely.

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    2. it's still a very strange angle to be holding the gun at.

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    3. Look at the angle it is at in his knee: its straight in, horizontal to the ground. Now the scratch angle could work, but consider how he must have had to hold it to do it himself like that if he was just trying to scratch it. Chances are that if he just tried to scratch his leg it would have been far easier to simply use the side of the gun, rather than so precisely pointing it like that. Its unlikely, and no matter how we look at this its all very strange and seems much more likely someone else did it to him- perhaps while he was on a ladder or something with the other persons shoulders level with his knees, perfect for aiming, or perhaps they were about to hand it to him or something when they pulled the trigger on accident. But i guess we will never know
      Connor

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    4. Actually com to think of it doc along a horizontal axis what anglewasit at? Like was it pointing more to the left or right? Or was it straight in to the knee, no angle at all?
      Connor again lol

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    5. Was he squatting or kneeling? That's the only way you can 'easily' do what he did.

      The x-ray made me wince in sympathy pain AND I wanted to ask him if he scratches his head with whatever tool he has in his hand.

      Maybe he should put aside the nail guns until he demonstrates he has a brain. Got an MRI of that?

      Wednesday

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    6. if he had his knee bent, he really would have had to work at it to get the gun there in the first place. and the gun would have had to be against his leg to drive the nail that well.

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    7. With a bent knee its even Less likely he did it himself unless for some reason it was all on purpose. Maybe the guy needs some seriouz psychological help but i somewhat doubt that its the case. Its more than likely that if anything hes covering up an accident someone else made so that theres no legal trouble.
      Connor

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    8. Maybe he parked it there while squatting or kneeling? I mean, I'm scratching my head but unless he had a companion who thought this would be a funny thing to do (or was drunk) that he's trying to protect, I'm at a loss. I suppose we'll never know and how great a thought is that!

      Wednesday

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    9. they say curiosity killed the cat.

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    10. I think I figured it out. He was kneeling. He didn't want to sit ALL the back on his heels, so he placed the nail gun on his half (thus positioning the head) and then sat back on it. Now, exactly how he reached back to remove the nail gun but pulled the trigger instead is what really has me puzzled. Of course, it takes but a moment to pull rather than push something and there have been carpenters who swallowed nails (don't hold them in your teeth!), so why not using a nail gun as an ottoman?

      Wednesday

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    11. I meant to write 'calf'. No idea why it came out as 'half'. W

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    12. I'm 100% with Shark on this - there is no way he did this to himself.

      The nail went right down the centre (as the Doc' suggests below) and we can see from the X-ray it's gone in straight and level (especially if it was uninteresting from the front - a straight nail would just look like a dark spot).

      This nail was put in by someone who deliberately placed it right in the centre of the back of the knee and can handle a heavy nail gun with enough skill to fire straight and lever. 10 to 1 it was whichever of his construction mates he was messing around with and he doesn't want to get into trouble.

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    13. Now we know he wasnt drunk (otherwise doc would have mentioned it) but perhaps the friend was or on something stronger. That suddenly makes it seem a little more possible as it could have been a drunk or high mistake. Would also explain maybe why the guy would be understanding enough that it wasnt malicious hence why hed cover it up. Or maybe this guy just has major issues. Perhaps perhaps not but boy is it fun to theorycraft.

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  5. *snicker* I used to be a carpenter like you... until I took a nail to the knee.

    *bows out*

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    1. I feel the need to acknowledge this comment *low 5*

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  6. Doc: Every single scenario or case you've posted can be competently managed by a board certified ER Doc. Just sayin.'

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    1. actually, no, many of them can't. particularly the ones that involve emergency surgery.

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    2. I'm talking about the cases he mentioned. Thank you.

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    3. John, I've mentioned many cases that have involved gunshot worlds to the abdomen, stabbing a with evisceration, etc. For someone who claims to know so much about medicine, you seem to know nothing about medicine.

      I'm leaving your comment up because it once again exposes your glaring stupidity. Thanks for that. If you choose to delete it, I'll remove the replies. Maybe.

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    4. Can we have a poll? W

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  7. Anon 05:46: Bye, John.

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  8. John has a thing for doctors so he stalks them online. If he didn't believe DocBastard was a real doctor, he wouldn't be here trolling the comment section after being banned. He attempts to discredit the credentials of the object of his attention but his attention proves he finds the object credible.

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    1. Is there anything John does OTHER than stalk people online?

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    2. Well ken he probably also stalks people in real life and tries to show how They are stupid, only revealing his own stupidity in the end. Just like how he does across the internet.
      Connor

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    3. Actually, no. I recall when he had a man crush on MKey1, now he's obsessed with DocBastard. Soon he'll be boiling virtual bunny rabbits in the comments section.

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  9. Since he's a doctor and a lawyer and a teacher and a pilot and a butcher and baker and a candlestick maker, I don't see how he has the time to stalk Doc.

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    1. You forgot thief. At least that was part of the rhyme back when I learned it. Wednesday

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    2. Im suprised he hasnt added politician to that list-oh crap i just gave him the idea didnt i?
      Connor

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  10. Doc: We're talking about this particular case. You have a nail gun injury that involves bony impalement of the medial/lateral epicondyle with the nail. My question is:

    How would you remove this nail?

    Do they need an ORTHOPEDIC TRAUMA SURGEON to remove that nail? How bout the GS trauma surgeon? Can they perform removal of a nail from bone? The same with EMP. Does the patient need to go to surgery?

    A carpenter would probably suggest to remove the nail by using a claw hammer. It might just work.



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    1. John - Good grief, the epicondyles weren't involved (not that it makes a bit of difference). The nail went through the intracondylar fossa, if you'd like to get technical. Nice try attempting to decipher a single lateral view of the knee without an AP or oblique view. But do continue trying to make yourself look smart, because every time you do it backfires and you end up looking like even more of an ass.

      As for your typically stupid questions, read the damned story. I made it quite clear who removed the nail. Perhaps you also want me to name the medications he was given and how he was anaesthetised? Perhaps you'd also like to know the brand of nail he used? How about the type of tape used to keep his dressing in place?

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    2. don't forget what brand of jeans it was and what he had for breakfast.

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    3. Can we please, please ignore the useless, ignorant, pathetic troll? He's not even amusing or clever.

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    4. He's a dull p***k but he does raise one interesting question: How in the name of all that's holy do you get a nail out if it's buried to the head in the top of a man's femur?

      "Instruments of death and destruction" are all very well, but that nail would be difficult enough to get out of two bits of wood without trashing them. In two pieces of living bone I can't imagine how you attempt it without turning a knee joint into a mass of bone splinters. Not to mention trashing all those handy soft bits that allow it to actually work as a knee.

      I the man ever walks without a limp then my hat is well and truly off to whoever took that nail out!

      Great story, as ever, BTW Doc'.

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    5. as for getting it out, first you have to grind away enough bone to get to the nailhead, and then use a pair of pliers to grip the nail, and do a twist-and-pull motion to work it out of the bone. the fact that it is living bone, theoretically helps a bit as there is some lubrication, from the body fluids.

      unlike wood, the bone will heal.

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    6. Pliers? Try removing a nail with pliers on a piece of wood. Good luck!

      Here;

      "Nail gun injuries are common, work-related injuries that typically involve bony impalement of an extremity with the nail. Treatment recommendations are well established, although suggestions for removing the nail itself have been lacking. In our hands, removal using typical operating room equipment has been challenging, usually resulting in nail head deformity and breakage, which makes completing the procedure even more difficult. As a result, we have revisited the tool designed solely for the purpose of nail removal, that is, a claw hammer: this tool is readily available from materials management at most hospitals, can be easily autoclaved, and is effectively used with a block or surgical pan lid to gain leverage and protect the soft tissues. We have found this method to be simple and extremely useful for nail removal for the nail-impaled patient."

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    7. how do you think I know that trick?

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    8. You learn something new everyday, Kenny Brown.

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  11. on the subject of nailguns, we had an incident hit the media some years back which you might find interesting:
    http://articles.chicagotribune.com/2006-04-25/news/0604250134_1_nail-gun-doctors-science-university-hospital

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  12. Wow the same thing happened to a builder at my dads construction site last month. Wonder if it's the same guy.

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  13. The article talks about the significance of effectively consulting, in designing the security system for the flow of information on the network. Expert evaluation of every aspect is rudimentary in developing a system that is highly functional.

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