28. The diagnosis of fractures of the radius is in general easy, when
they occur at the lower end, or in the middle (25). In these two
cases, a depression more or less perceptible, on the external side
of the fore-arm; an inability to perform pronation or supination,
by the action of the muscles alone; and a severe pain, necessarily
resulting from moving the bone in this two-fold direction. Such are the
particular signs or appearances which first disclose the existence and
the place of the fracture. The reality of the accident is afterwards
more fully confirmed by the signs common to all fractures, namely, the
flexibility of the bone, the crepitation perceived by moving it in
different directions, &c.
29. Desault cautioned his pupils not to confound this last sign or
symptom with a kind of noise, sometimes heard in the sheaths of the
tendons of the extensor longus, extensor brevis, and abductor longus; a
noise resulting from a filtration of synovial fluid into the sheaths,
or produced by some other cause. But, besides this crepitus in the
sheaths being a very rare occurrence, it is always easy to distinguish
it from a crepitation of the bone, by this circumstance, that the first
is heard on merely pressing the parts, but the latter only by making
the bony surfaces rub against each other. Besides, by an experienced
ear there is no danger of any mistake being committed.
30. If the fracture exist at the upper end, the thick muscular covering
which there surrounds the radius, renders the diagnosis more difficult.
Petit has, however, thrown some light on the subject, by judiciously
advising to place one hand on the upper extremity of the radius, and
with the other to make the fore-arm rotate on this bone. The solution
of continuity or fracture will be rendered evident, if, in the midst
of these motions, the head remain stationary. But if, on the other
hand, it rotate, it has sustained no injury. These two circumstances
can be easily explained; but, it is not so easy for the practitioner to
avail himself of them in every case. This precept may also be applied
in cases where a considerable swelling, occupying the whole fore-arm,
conceals from the touch of the surgeon the fragments of the bone, even
when broken in the middle.
§ IX.