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Old January 31, 2006, 07:57 AM   #9
Odd Job
Senior Member
 
Join Date: January 2, 2006
Location: London (ex SA)
Posts: 476
Unfortunately the ballistic variables combined with the anatomical variables and added to the clothing and intermediate target variables render it impossible to predict with certainty what the effects will be when a human sternum is shot. One can only offer very general observations based upon X amount of cases. A gunshot sternum isn't a very common sighting in a hospital. In fact I rate it as number 2 on my list of 'hard to come by' bone fractures due to gunshot wounds. Number 1 on my list is the nasal bone. But anyway, I think it is important to realise that no two shootings are ever the same. Sure, there have been many cases of 'long bone' shootings in which a 'characteristic' fracture pattern has been seen, and there have been many cases where the flat bone of the skull vault has been perforated and a 'characteristic' fracture pattern has been seen too. Those injuries are relatively common. We more-or-less know what can happen when those bones are shot. My opinion is that a sternum will not fragment much when shot with a handgun. It is flat and has a lot of support from the anterior costal cartilages and the muscles of the chest. Of course, all these 'opinions' go out the window when you have an unusual trajectory or a variation in the anatomy. But as it stands I can't give you an example of a sternum fracture because of a gunshot wound.
But have a look at this radiograph:



This is a guy who was shot while prone on a bed. He sustained multiple rib fractures (white arrows) but hardly any fragmentation of the bullet occured. The red arrows show lead specks from the bullet. The blue arrows show technical artefacts from a dirty intensifying screen. The cropped image on the right has been sharpened a little so you can make out the fractures a little more easily. Now this may seem like not such a big deal, but this is a classic case of the bullet refusing to read any of the medical or ballistic text books before entering the patient. Those ribs have been hit almost edge-on and yet instead of deflecting anteriorly or posteriorly, the bullet has gone on to fracture 4 ribs in turn. Furthermore the degree of displacement of one fracture relative to another is different in each case. Who could have predicted this? The patient sustained a pneumothorax (collapsed lung for non-medical folk), but it is impossible to tell whether this was because of the passage of the bullet itself or the deflection of sharp rib fragments into the lung. If I was pressed to choose, I would pick the rib fragments. Those are very sharp and surgeons are wary of them!

And one more case (or I'll be told not to turn TFL into a forensic forum ) involves a young man who was shot in the lower leg by a jacketed projectile, probably a 9mm (or thereabouts) FMJ.



Here is a fractured left tibia and fibula (the tibia is the main bone, the thick one that takes all your weight and the thin one is the fibula which is not a big deal if fractured). There is a deformed bullet medially (on the inside of the leg). What's interesting here is that it is very difficult to understand the trajectory in view of the fact that there is an entrance and exit wound, both bones are fractured and the main mass of the bullet remains in the wound. The fracture pattern and displacement of bone fragments from the tibia indicates that the guy was shot from the antero-lateral aspect (from 10 o'clock), and the tibia was fractured first. There was a deflection posteriorly (between 6 and 7 o'clock) which resulted in the fibula being fractured. Then from the fibula the bullet was deflected medially (3 o'clock) and that is where it came to rest. But again, there is no telling whether the exit wound was caused by a piece of bullet (we would call it a daughter fragment) or by a piece of tibia. I say tibia and not fibula because I will go out on a limb and declare that all the pieces of the fibula are still in situ. I guess you could call this a case of ballistic pinball! Gunshots involving bones can be very strange...

By the way, skin breach markers are essential in any kind of analysis of bone fragment displacement in gunshot injuries and I hope you medical folk out there are enforcing this in your hospitals. That first chest case doesn't have any because it is not the initial X-ray series, but initial ones must be marked.
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File Type: jpg Ankle.jpg (163.9 KB, 1497 views)
File Type: jpg Chest.jpg (185.1 KB, 1504 views)
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