In
Dupuytren's fracture, when the talus passes up between the tibia and
fibula, there is great broadening of the ankle.

[Illustration: FIG. 94.--Radiogram of Pott's Fracture with lateral
displacement of foot.]

There is often considerable difficulty in distinguishing a _sprain_ of
the ankle from a fracture without displacement, as both forms of
injury result from the same kinds of violence, and are rapidly
followed by swelling and discoloration of the overlying soft parts. In
a sprain, the point of maximum tenderness is over the ligaments and
tendon sheaths that have been damaged, while in fracture the site of
the break is the most tender spot. The X-rays are useful in the
diagnosis of doubtful cases.

_Treatment._--In those cases of fracture of the lower end of the
fibula in which there is no marked displacement,--and they constitute
a considerable proportion,--the limb should be massaged and laid on a
pillow between sand-bags, or placed in a box splint for two or three
days, until the swelling subsides. Some form of rigid apparatus, such
as side poroplastic splints fixed in position with an elastic bandage,
which will allow the patient to get about with crutches, is then
applied. This is removed daily to permit of massage and movement being
carried out--a point of great practical importance, because, if this
is neglected, not only does union take place more slowly, but the
stiffness of the ankle and oedema of the leg and foot which ensue,
prolong the period of the patient's incapacity and endanger the
usefulness of the limb.

It is in cases of this kind that the _ambulatory method_ of treatment
yields its best results. When, in the course of two or three days, the
swelling has subsided, a plaster-of-Paris case (Fig. 95) is applied in
such a way that when the patient walks the weight is transmitted from
the condyles of the tibia through the plaster case to the ground, no
weight being borne by the bones at the seat of fracture. The apparatus
is applied as follows: A boracic lint bandage is applied to the limb
as far as the knee, and protecting pads or rings of wool are placed
over the condyles of the tibia, the head of the fibula, and the
malleoli. A pad of wool about 3 inches thick is then placed under the
sole and fixed in position by a plaster-of-Paris bandage, which is
carried up the limb in the usual way. The case is made specially
strong on the sole, around the ankle, up the sides of the leg, and at
the bea