regard to the spread of the fissures in the long axis of the bone
into neighbouring articulations I think fractures produced by bullets of
small calibre differ considerably from those produced by larger
projectiles, in that their general tendency is not to extend beyond the
commencement of the cancellous bone forming the joint end. This is
perhaps capable of explanation on several grounds: first, the smaller
area of impact results in the assumption of a strongly marked stellate
figure, the radiating fissures of which rapidly reach the lateral limits
of the shaft, producing a solution of continuity in the bone which
interrupts the continuance of the action of the wedge represented by the
bullet. Secondly, the small size of the wedge itself is opposed to the
wide separation of the parts directly implicated, which is necessary for
the continued progress of the process of fissuring, and again the
rapidity of passage minimises the period during which the force is
exerted. It is in these points that I believe the chief differences
between the modern and old gunshot fractures find their explanation,
since with the larger bullets fractures extending from some distance
into the joints were a somewhat special feature. In addition it is
probable that the alteration in structure at the junction of the shafts
with the cancellous ends also tends to check the regular extension of
the fissures, as a similar limitation is illustrated even in some
fractures by Snider bullets. Fig. 51 of the lower end of the femur
illustrates a not uncommon lower limit to a comminuted injury in this
region.

[Illustration: FIG. 51.--Lower end of Femur. From Case needing
amputation. It shows the usual tendency of the fissures to stop short of
the articular ends of the long bones]

The degree and nature of the comminution also vary with the directness
of impact on the part of the bullet. The more nearly this approaches at
a right angle, the more severe is the local comminution, but probably a
lesser area of the shaft is implicated. Plate V. shows an example of
this: all trace of continuity is lost, a wide gap separates the bone
ends, while the fragments themselves have been for the most part driven
altogether out of the wound. Oblique impact, on the other hand, may
widen the comminuted area at the point of impact, while, if the bullet
retains sufficient force and regularity of outline, it may then travel
'cutting its way' through the remainder of the bone