FRACTURE OF THE ULNA. 
527 
passed the fore feet through a hay-rack. In general the olecranon 
breaks completely off, loosening the lower point of insertion of the 
extensors of the elbow, and producing symptoms like those of radial 
paralysis. 
Birrenbach saw complete fracture about IP inches below the joint. 
When, as is generally the case, the fracture is lower and extends into 
the elbow-joint, lameness and pain are severe when weight is placed 
on the limb. The displacement of bone can sometimes be directly 
observed. 
Mann noticed permanent lameness and symptoms of radial paralysis 
in a foal which had been kicked on the elbow. 
Post-mortem showed that the ulna was com¬ 
pletely broken off from the radius, and that 
a space of nearly two inches existed between 
them. In this case the ligamenta trans- 
versa and the ligamentum interosseum must 
have been ruptured. 
Prognosis and course. Union of trans¬ 
verse fracture of the ulna is rare; most 
horses suffering from it have sooner or later 
to be killed. Gunther says foals recover. In 
man, transverse fractures of the olecranon 
only reunite by fibrous callus, because, it is 
said, of the displacement of broken fragments 
by the pull of the muscles, and of the failure 
to form bony callus on account of the absence 
of periosteum. On the other hand, A. Cooper 
has shown by experiments on dogs that in 
longitudinal fracture of the olecranon a 
bony callus always forms. The unfavourable 
course which transverse fracture of the ulna takes in the horse must be 
referred to the great dislocation produced by the pull of the triceps 
muscle, and to the fact that the fracture almost always extends to the 
articular surface. Fig. 195, drawn from nature, shows a typical fracture, 
such as is usually seen in horses. Moller never had a recovery. Under 
exceptionally favourable circumstances, fracture of the ulna may reunite. 
In pigs, dogs, and cats, in which the ulna forms a bone distinct from the 
radius, recovery is much commoner, the radius acting to some extent as 
a splint for the broken ulna. 
Treatment. As in horses and ruminants no effective bandage can be 
applied at this point, treatment is confined to keeping the animal quiet, 
or possibly to placing it in slings. The action of the triceps muscle 
interferes with healing, and therefore it is best to prevent animals lying 
Fig. 195.—Fracture of the ulna 
in a horse. 
