10. It follows from what has been said on the displacement of the
fragments (8), and on the causes which have a constant tendency to
re-produce this displacement (9), that the extending forces, intended
to remove it, should be, in general, less powerful than in most other
fractures, because their principal object is, to restore to the limb
its natural length, which is here but very little affected.
11. Previously to the application of these, it is necessary, according
to the precept of Hippocrates, to place the fore-arm in a middle state
between pronation and supination, flexion and extension. This position
is highly favourable to the relaxation of the muscles, and is that,
above all others, as the father of medicine observes, which those who
have sustained a fracture naturally assume, and which alone they can,
for a long time, retain, without experiencing any inconvenience.
12. The fore-arm being thus placed, an assistant makes extension, by
taking hold of the four fingers; a mode to be adopted in preference
to that of Petit, who directs us to make extension at the wrist; for
the real momentum or force of a power is in the inverse ratio of its
distance from the place of resistance. At the same time, another
assistant makes counter-extension on the humerus, which he grasps with
both his hands, in such a manner, that his thumbs correspond to the
back part of it, while his fingers cross each other anteriorly.
13. It further follows, from what was said (8 and 9), that the process
of conformation, so often useless and even injurious, in other
fractures of bones, is necessary here, to restore to the fragments that
exact contact which they have lost, in a transverse direction. If the
displacement be forward, the surgeon pushes both fragments backward,
while the assistants maintain the extension. If the bones project
backwards, they must be pushed in the contrary direction. As to a
lateral displacement (8) in which the broken ends approach each other,
it is not altogether useless, as Petit observes, to endeavour to remove
it, by forcing the muscles into the space between the bones. This
is done by making a moderate pressure on the anterior and posterior
surfaces of the fore-arm, in order that the bones, being thus removed
from each other, may come in contact with their broken ends. If this be
done, when the apparatus is first applied, the reduction is attended
with but little difficulty, and the ends of the fragments are easily
retained in apposition.
§ VI.