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Fracture detector

A pre-X-ray test for common fractures
  (+9, -1)(+9, -1)
(+9, -1)
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Today, my daughter broke her arm (she's fine, and quite proud of her cast). She fell over and landed badly, and the school nurse, not suspecting a fracture, gave her an ice pack on the assumption it was a bruise. Only when we got her arm X- rayed was it clear there was a break - there wasn't a huge amount of pain or anything obvious, and nine times out of ten it would have turned out to be what the school nurse thought - a bruise.

This got me wondering if there was some easier way to tell if there were a fracture before schlepping someone off to casualty for an X-ray. Bones are pretty rigid (at least after early childhood), and must transmit vibrations quickly and well. So, suppose you had a transducer which could be pressed firmly onto the skin near one end of the bone (*not* near the suspected fracture!), which sends out brief pulses of sound. A second, stethoscope-like transducer detects the sound waves arriving at the other end of the bone and, from the delay and intensity, can tell whether there's a continuous bone-path between the two ends. If there's a fracture, then obviously an X-ray is needed.

This would probably work only in certain cases. For example, a break in the ulna could be easy to detect, since the transducers can be pressed firmly against the wrist-bone (do I mean the knobbly end of the ulna?) and the elbow. Breaks in the humerus might be harder to detect, since I don't think the upper end of the humerus comes close to the skin. But, in some situations, it might be a handy and simple diagnostic tool.
Basepair, Jul 12 2005

patent WO2004093686 http://v3.espacenet...DX=WO2004093686&F=0
A method of diagnosing a subject by delivering ultrasound signals to a bone surface [xaviergisz, Jul 13 2005]

Handheld ultrasound diagnosis of extremity fractures http://www.ncbi.nlm...15376408&query_hl=5
...successfully identified long bone fractures in three patients using hand portable ultrasound... [xaviergisz, Jul 13 2005]

TDR or Time Domain Reflectometry http://www.tscm.com/tdr.html
Look at the amplitude and the position of the reflections. A cable tester using this method can be held in the hand. [Ling, Jul 13 2005]

Curing broken bones with ultrasound http://www.fda.gov/...tures/396_bone.html
[DrCurry, Jul 13 2005]

one I broke earlier. x-ray_20machine_20n...the_20post_20office
[po, Jul 13 2005]

Forearm Diseases http://focosi.alter...#forearm%20diseases
Elbows are discussed above this. [reensure, Jul 14 2005]

Journal of Trauma http://www.jtrauma....!-949856031!9001!-1
Advanced Ultrasonic Diagnosis of Extremity Trauma: The FASTER Examination
94% accurate in 158 examinations performed in 95 patients. [reensure, Jul 16 2005]

Sonsonite, Inc. http://www.sonosite...ducts_overview.html
Weigh in at as little as three pounds (compare to your Blackberry) [reensure, Jul 17 2005]

[link]






       maybe you could use a needle to actualy contackt the bone and transmit the vibrations along that.
ferox, Jul 13 2005
  

       You might need a very sensitive detector as the vibrations might travel through fractured bone if the two pieces are still in contact or there is another bone connecting the pieces. It is a cool idea though. [+]
pooduck, Jul 13 2005
  

       great idea - I wonder if anyone's tried it before.
neilp, Jul 13 2005
  

       I like it! You seem to have two options: sound transmission and ringing.   

       A dry bone with nothing around it would certainly ring at a certain tone, much like a bell, but might not do so in the body. I was taught to test new grinding wheels for invisible cracks by ringing them. I once kept a cracked dinner plate just to demonstrate the difference in tone between it and a good plate. It may be possible to determine what the bone should sound like if not fractured.
baconbrain, Jul 13 2005
  

       I have this mental Norman Rockwell image of a kindly country doctor holding a tuning fork to a sobbing child's arm.
DrCurry, Jul 13 2005
  

       Of course medical use of ultrasound is baked, but I've only seen it for imaging and questionable physiotherapy. Ultrasound for bone flaw detection? Now that's got me thinking. Industry uses ultrasound for flaw detection, but I think the material has to be homogenous, which might be a problem here (plenty of noise from skin/meat/bone interfaces).   

       Later: ah, links. Righto.
Texticle, Jul 13 2005
  

       Check for unusual reflections (time domain reflectometry), same as finding a fault in a cable, especially fiber optic cable. Compare left and right arms/legs to each other.   

       <aside> I have often wondered why the diagnosis is required, for minor fractures. Confirmation that it hurts?
Ling, Jul 13 2005
  

       //Compare left and right arms/legs to each other.// Brilliant, Ling! So obvious once it's mentioned. That is the key to this idea.
baconbrain, Jul 13 2005
  

       Hmm. The links show that ultrasound can be used successfully, som I guess this is partly baked. However, I presume that the systems described are using fairly sophisticated equipment similar to that used for (eg) foetal imaging? I was hoping for a simpler system - just a couple of transducers to measure time delays in transmission along the bone, rather than imaging through reflection. But on the other hand, perhaps a "simple" system might be too unreliable to be worthwhile.

Ling's point about comparing limbs is excellent and would remove a lot of the 'noise' from the system.

//I have often wondered why the diagnosis is required, for minor fractures. Confirmation that it hurts?// Well, I would have thought the same. But this fracture produced no more pain than a bad bruise, and she could rotate her forarm and flex her wrist. Nevertheless, the X-ray revealed a break right through the bone which definitely required a cast. I was surprised too.
Basepair, Jul 13 2005
  

       a TDR system would be relatively simple: send a sound pulse down the bone, and listen for the echos. No need for an image. See link for example on cable testing.
p.s. Best wishes to your daughter. I hope it doesn't ache too much at night.
Ling, Jul 13 2005
  

       This is a great idea - I love ideas that will work with an affordable amount of current technology. Unfortunately the "needle into the bone" method would be both the most reliable and the most painful.
wagster, Jul 13 2005
  

       A agree the needle would give you the cleanest signal, but it then becomes a 'procedure' and more of a faff than an X-ray. Perhaps just a blunt pointy probe (if you see what I mean) that could be pressed against the skin where the bone was nearest the surface.
Assuming that bone- transmitted sounds are significantly faster/stronger than flesh-transmitted ones (perhaps best for shear waves rather than compression waves?), I'd expect the skin-bone-skin signal to be distinguishable from the skin-flesh- skin one, though I don't know how clear it would be. And as Ling said, an echo returning from the break might be an alternative method (would this work in the case of an irregular shaft like a bone, which can have bumps and knobbles where muscles/tendons attach?).
Ling - many thanks - arm was fine last night, so hopefully it'll all go smoothly. She was at school today enjoying her fame!
Basepair, Jul 13 2005
  

       In all fairness, couldn't the doctor just use a sonogram? And then start curing the fracture on the spot (see link).
DrCurry, Jul 13 2005
  

       The problem with having flesh in the way is that flesh tends to absorb high frequencies. The resonant frequency of a bone is pretty high already (I'm guessing here from the memory of what a dropped sheeps bone sounds like) and will double if there's a break in the middle. You might be right about the skin/bone/skin signal though - it will hopefully transmit *enough* hf.   

       How's about this: make a machine that fires a quick pulse of sound (pink noise would be good) into the bone (via the thinnest piece of flesh), records the resonance left behind in the bone (it will vibrate for a small fraction of a second), and stores an analysis of the frequency response of the sound. You then use it once on the injured arm and once on the opposite arm. The machine compares the two sets of frequency response data and tells you whether the arms sound the same or different. If they sound different there's probably a fracture, if not then there isn't (or it's very small). Best of all, this should be quite compact and cheap. [Dr C] - this could be made for £50-100 and kept in school first-aid cabinets.
wagster, Jul 13 2005
  

       [Wagster] - sounds plausible to me :-) I guess in the end it's a case of suck-it- and-see. I wonder if there's research funding available to break kids arms? But seriously, I'm glad the idea is at least not completely unfeasible. Also glad to hear you say "£50-100" - this was the sort of thing I was hoping for (not a hospital instrument, but a a first- aid accessory). Certainly, any indication of a fracture would be followed up with a trip to hospital and an X-ray.
Basepair, Jul 13 2005
  

       Injury to the growth plates of the ends (epiphyses) of long bones is the most significant, or at least is a major cause of adult deformities arising from childhood injuries. Most of these fractures and the subsequent nonunion that might develop, particularly after repetitive stress on the fracture site (read that as "suck it up and get back in there") are amenable to aggressive treatment. That is why proper identification of a child's injury is so important.   

       I'd be interested to know if there is a predilection to the onset of carpal tunnel syndrome in adults who were victims of mismanaged growth plate injuries as children.
reensure, Jul 13 2005
  

       //That is why proper identification of a child's injury is so important.// I agree - ideally you'd want to guarantee detection of a fracture. Presumably, the highest rate of non-detection of fractures is in cases like my daughter's, where there was little pain and it looked more likely to be a bruise. I guess any 'simple' fracture detector would have to tread a narrow line between false alarms and false negatives. Too many false alarms and you'll have people wanting X-rays even though common sense says it's just a bruise. False negatives, on the other hand, would be worse.
On the other hand, relying only on 'eyeballing' and pain-levels must also have a significant rate of both false positives and false negatives. (Incidentally, on a personal note, I presume that the growth-plate at the distal end of the ulna is pretty close to the head of the bone and not a couple of inches proximal to it?)
Basepair, Jul 13 2005
  

       I'd hope so. There is a classical type of fracture of that bone. Watch the 5 Ps. These are pain, pallor, pulselessness, paresthesias, and paralysis. Pain is the earliest sign. Symtoms get no worse ... have no fear.
reensure, Jul 13 2005
  

       //pain, pallor, pulselessness, paresthesias, and paralysis// Nah, she didn't have any of those. What is this 'classical fracture'? I was surprised that this one was clean across (rather than having any longitudinal 'splits'. (Sorry, off-topic here in a purely self- interested way).
Basepair, Jul 14 2005
  

       heh. Classical fracture: I'm surprised no one took the time to put a 'camp spin' on that. It's just something I say when I don't have a medical degree, but recognize a response to some specific injury that could only be named eponymously or by reference to specific tendons, nerves, or bony prominences involved. Again, I don't diagnose conditions. (see link) I'd rather you'd search to your own limit for that type of thing ... but if the condition isn't getting worse, there should be minimum swelling to produce nerve damage or contractures of any muscles. Beyond that, the likelihood of growth plate injury two inches proximal from a wrist is small, but the important thing to recognize is that stability and nourishment will heal the fracture quicker and with less risk of complications.
reensure, Jul 14 2005
  

       Ah. Well, one has to admire a good bluff. If you ever need any dental work done, let me know.... :-,
Basepair, Jul 14 2005
  

       [Basepair] I sympathize with your daughter as we will both be recovering from broken bones. She will sooner than I, I assume.
I wonder if this is the chance for her to become a baker? Perforated or Castellated Casts? I imagine that the standard cast is a pain in the cast for those that have to endure it.
If when formed, the cast is wraped in a perforating or castellating plastic forming agent, the aeriation of the skin underneath the cast might be a such a relief that those who've not had such would should wiggle with joy at the concept?
I knew at once I broke my bone as I heard it snap/pop (in 4 pieces). I support this idea with all of my heart & pain.
My best wishes for the recovery of your daughter!
Zimmy, Jul 16 2005
  

       Thanks, [Zimmy]. I also worry about the close skin contact of a conventional plaster - I'm amazed that the skin doesn't get infected with such long enclosure. (I understand, though, that things do get pretty manky in there!).

A 'breathable cast' would be good if it doesn't already exist. I also wondered if casts couldn't be 'accessorized' to compensate for the loss of limb-use. A few clipboard-style clips and knobs would be handy for holding things; perhaps also a pen- holder (not to write with, but to store the pen), an inbuilt watch....the list is endless.
Basepair, Jul 16 2005
  

       <HB off topic> ... mmm liability. </>   

       When radiographs can be relayed to a remote emergency doctor, I think a school nurse (for example) would be in a far better position to decide if a call to EMS is necessary.
reensure, Jul 17 2005
  
      
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