Inspired by PA4Ortho, I submit the following:
Allow me to briefly don the cape of Captain Obvious, and state that Xray machines are somewhat hard to come by out in the field.
However, there is a technique to detect long bone fractures in the field with a stethoscope and tuning fork, absent the gold standard X-ray.
It is published here, and the technique is as follows:
Place your stethoscope and your tuning fork ( a 128 Hz model was used, but I suspect you could use a 256 Hz model) on opposite sides of the location of the suspected break. Compare to the uninjured side. You should hear a clear transmission of the sound of the tuning fork on unbroken bones, and it should be dampened on the site of injury.
In the publication above, this was about 80% sensitive (picked up 10 out of 12 that had a fracture) and 80% specific (correctly ruled out 20 of 25 who did not have a fracture).
See here for related video:
My experience with this is that occasionally the vibration of the tuning fork caused increased pain at the site of the break; the article above claims this is “painless”. My patients never complained of dramatically increased pain, just noticeable increased pain, so I did not feel as if I tortured them. My hypothesis is that causes the broken ends of the bone to vibrate against one another, and this caused worsening pain at the fracture site. It has no effect on unbroken bones.
I’ve not formally tested or published that last bit.
I know, I know, I’m breaking my rule about citing data. But there it is.
Assignment #1: find a tuning fork (they are very cheap on Amazon, and much cheaper than an Xray machine) and actually do this. Practice so that you know what normal sounds like; afterwards, abnormal is quite obvious.
Update: Updated to better reflect the article quoted. Also, the references from the article cite several other papers that also investigated this technique, which you can review at your leisure.