es occurs, and
in rare cases results in arrest of the growth of the bone, leading to
a varus condition of the hand and bending of the radius. Sometimes the
separated epiphysis fails to unite, and although this gives rise to no
disability, it is liable to lead to errors in the interpretation of
skiagrams.

The _treatment_ is similar to that for the corresponding injuries of
the radius.

Simultaneous separation of the _epiphysis of both radius and ulna_
sometimes occurs, and, as a result of severe violence, may be
compound, the lower ends of the diaphyses projecting through the skin
on the palmar aspect above the wrist.

#Fracture of Carpal Bones.#--The use of the Roentgen rays has shown
that fracture of individual carpal bones is commoner than was
previously supposed, and that many cases formerly looked upon as
severe sprains are examples of this injury.

The _navicular_ (scaphoid) and _lunate_ (semilunar) are those most
commonly fractured, usually by indirect violence, by forced
dorsiflexion from a fall on the extended hand. The clinical features
are: localised swelling on the radial side of the wrist, increase in
the antero-posterior diameter of the carpus, marked tenderness in the
anatomical snuff-box when the hand is moved laterally, especially in
the direction of adduction, and, rarely, crepitus. The median nerve is
sometimes over-stretched or partly torn. In many cases, however, the
symptoms are so obscure that an accurate diagnosis can only be made by
the use of the X-rays (Fig. 49). Codman recommends taking pictures of
the navicular by placing the two wrists of the patient in adduction,
and of the lunate, in abduction.

[Illustration: FIG. 49.--Radiogram showing Fracture of Navicular
(Scaphoid) Bone.]

The _treatment_ of simple fractures consists in massage and movement.
Codman and Chase recommend excision of the proximal half of the
fractured bone, through a dorsal incision to the lateral side of the
extensor digitorum communis. When the fracture is compound, the loose
fragments should be removed.

DISLOCATIONS IN THE REGION OF THE WRIST

Dislocation may occur at the inferior radio-ulnar, the radio-carpal,
mid-carpal, inter-carpal, or carpo-metacarpal joints, but the strong
ligaments of these articulations, the comparatively free movement at
the various joints, and the relative weakness of the lower end of the
radius whereby it is so frequently fractured, render dislocation a
rare form of injury.