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.
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 Röntgen 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.
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.