[Illustration: FIG. 47.--Radiogram of Smith's Fracture.
When the deformity is not well marked, this injury may be mistaken for forward dislocation of the wrist, for fracture of both bones low down, or for sprain of the joint.
The _treatment_ is carried out on the same lines as in Colles' fracture.
_Longitudinal fractures_ of the lower end of the radius opening into the joint usually result from the hand being crushed by a heavy weight or in machinery. They are often compound and comminuted.
#Separation of the lower epiphysis# of the radius, which is on the same level as that of the ulna and lies above the level of the synovial membrane of the wrist-joint, is comparatively common between the ages of seven and eighteen, especially in boys, and is caused by the same forms of violence as produce Colles' fracture.
Although clinically the appearances in these two injuries bear a general resemblance to one another, separation of the epiphysis may usually be identified by the directly transverse line of the dorsal and palmar projections, the folding of the skin observed in the palmar depression, the absence of abduction of the hand and the ease with which muffled crepitus can be elicited (E. H. Bennett). The deformity is readily reduced, and the fragments are easily retained in position.
This injury is often complicated with fracture of the shaft or styloid process of the ulna, or with dislocation of the radio-ulnar joint, and it is not infrequently compound, the lower end of the shaft being driven through the skin on the palmar aspect immediately above the wrist. Impairment of growth in the radius seldom occurs; when it does, it results in a valgus condition of the hand (Fig. 48), calling for resection of the lower end of the ulna.
[Illustration: FIG. 48.--Manus Valga following separation of lower radial epiphysis in childhood.
The _treatment_ is the same as for Colles' fracture.
#Fracture of the Lower End of the Ulna.#--The lower end of the _shaft_ of the ulna is seldom fractured alone. The _styloid process_, as has already been pointed out, is frequently broken in association with Colles' and other fractures of the lower end of the radius.
Separation of the _lower epiphysis_ of the ulna sometimes 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.