." Although of a similar nature, and
produced by the same forms of violence, these vary considerably in
their anatomy and clinical features. They are all the result of
_combined eversion and abduction_ of the foot--produced, for example,
by slipping off the kerbstone, or by jumping from a height and landing
on the medial side of the foot.

When forcible _eversion_ is the chief movement, the tightening of the
deltoid (internal lateral) ligament usually tears off the medial
malleolus across its base. The talus is then brought to bear on the
lateral malleolus, and the force continuing to act, the lower end of
the fibula is pressed laterally, and breaks close above the
malleolus. The tibio-fibular interosseous ligament may rupture, or the
outer portion of the tibia, to which it is attached, may be avulsed.
This form is sometimes called _Dupuytren's fracture_. When the bones
are widely separated in Dupuytren's fracture the talus may be forced
up between them.

When the movement of _abduction_ predominates, the deltoid ligament is
usually ruptured, or the anterior edge or tip of the medial malleolus
torn off. The tibio-fibular interosseous ligament usually resists, and
an oblique fracture of the fibula 2 or 4 inches above its lower end
results.

_Clinical Features._--In a considerable proportion of cases--in our
experience in the majority--this fracture is not accompanied by any
marked deformity of the foot, and the patient is often able to walk
after the injury with only a slight limp.

In others, however, the deformity is marked and characteristic (Fig.
94). The foot is everted, its inner side resting on the ground. The
medial malleolus is unduly prominent, stretching the skin, which may
give way if the patient attempts to walk. The foot, having lost the
support of the malleoli, is often displaced backward, and the toes are
pointed by the contraction of the calf muscles. There is abnormal
mobility--both from side to side and antero-posteriorly--and crepitus
may be elicited. The points of tenderness are over the deltoid
ligament or medial malleolus, the inferior tibio-fibular joint, and at
the seat of fracture of the fibula. Distal pressure over the shaft of
the fibula, or on the extreme tip of the malleolus, may elicit pain
and crepitus at the seat of fracture. There is usually considerable
ecchymosis and swelling in the hollows below and behind the malleoli;
and the malleoli appear to be nearer the level of the sole.