ushing the carpus into position. A moulded poroplastic
splint, which keeps the hand slightly dorsiflexed, adds to the comfort
of the patient, but this should be removed daily to admit of movement
and massage being employed.

[Illustration: FIG. 50.--Dorsal Dislocation of Wrist at Radio-carpal
Articulation, in a man, aet. 24, from a fall.]

#Dislocation of Carpal Bones.#--The two rows of carpal bones may be
separated from one another, or any one of the individual bones may be
displaced. These injuries are rare, and result from severe forms of
violence, usually from a fall on the extended hand. Pain, deformity,
and loss of function are the ordinary symptoms. The treatment consists
in making direct pressure over the displaced bone, while traction is
made on the hand, which is alternately flexed and extended.

Of these injuries that most frequently observed is displacement of the
_head of the capitate bone_ (_os magnum_) from the navicular
(scaphoid) and lunate (semilunar) bones. Frequently these bones are
fractured, and fragments accompany the displaced os magnum. In full
palmar flexion of the wrist the displaced head of the os magnum forms
a prominence on the dorsum opposite the base of the third metacarpal,
which temporarily disappears when the hand is dorsiflexed. There is an
increase in the antero-posterior diameter of the wrist, situated on a
lower level than that which accompanies fracture of the lower end of
the radius; flexion and extension of the wrist are limited; and in
some cases there are symptoms referable to pressure on the median
nerve. By keeping the hand in the dorsiflexed position for a week or
ten days, the bone may become fixed in its place and the function of
the wrist be restored, but it is often necessary to excise the bone.

The _lunate_ may be displaced forward by forcible dorsiflexion of the
hand, and forms a projection beneath the flexor tendons; there is
usually loss of sensibility in the distribution of the ulnar nerve in
the hand. The most satisfactory treatment is removal of the bone.

In a few cases the _navicular_ has been displaced (Fig. 51), and has
had to be subsequently replaced by operation. Separation of any of the
other bones is rare.

[Illustration: FIG. 51.--Radiogram showing Forward Dislocation of
Navicular (Scaphoid) Bone.]

#Carpo-metacarpal Dislocations.#--Any or all of the metacarpal bones
may be separated from the carpus by forced movements of flexion or
extension. T