SHARP FORCE 

Sharp force trauma refers to the injuries caused by such things as knives, saws, and axes.  In fact, sharp force trauma is only blunt force trauma with a sharp edge.  Many times sharp force trauma is a combination of sharp and blunt trauma.  The injury created by sharp force is variant on a number of factors including the sharpness of the weapon.  A sharp edge will create a look in bone that is reminiscent of whittle wood.  Dull edges, however, will gouge bone, leaving uneven edges.  Through the examination of the marks left, forensic specialists can attempt to identify the weapon involved and determine purpose of the injury.  For example, if a cut mark occurs on multiple surfaces it is more likely that it occurred as the result of dismemberment rather than a murder attempt.  Forensic specialists look at such things as the sequence of the cut marks, whether or not the blade was serrated, and the size, shape, and set of blades and teeth on a saw.  Also, the pattern and angles of the cuts can show where an attacker stood in relation to the victim.

Stab wounds usually leave a slight incision where the edge or the point of the weapon strikes the bone.  This type of evidence is very easy to miss if a bone is not properly cleaned off first.  The characteristic of a stab wound is a bending effect on the bone.  This bending results in a raised edge of bone that curls inward or outward along the edges of the incision (see knife wounds).

Sharp force trauma is not, however, always the result of an attack.  In prehistoric time, trephination was a commonly performed surgery; it dates back to the Mesolithic.  Trephination is the act of removing a bit of bone without damaging the underlying blood vessels, tissue, and brain.  The reasons that trephination was performed are unknown, but the prominent theory is that it was used to treat head injuries - such as swelling of the brain or the removal bone fragments (see trephination).
 
 

* Images courtesy of Dirkmaat, various pages