FRACTURES OF THE SESAMOID BONES. 
625 
suddenly fell in the street the first time of going to work, and could not be 
got up. On post-mortem, the sesamoid bones of both fore limbs were found 
horizontally fractured, and in each of the hind feet the flexor pedis perforans 
tendon was torn away from its point of insertion into the os pedis. 
Continued rest appears to cause change both in bones and tendons; the 
view that such accidents are solely caused by the animal capering about is 
scarcely defensible. 
The symptoms are generally pronounced. In horizontal fractures the 
fragments are drawn apart and the fetlock-joint sinks to the ground, being 
no longer fixed by its suspensory ligaments. The accident is distinguished 
from rupture of the flexor pedis perforans or perforatus by the normal 
position of the hoof, the toe of which, in rupture of the tendons, is 
directed upwards, so that it no longer touches the ground. Rupture of 
the suspensory ligament produces the same change in position, but is 
easily detected on palpation. In fractured sesamoid there is excessive 
lameness, pain on pressure over the fractured bone, and sometimes 
slight crepitation. In perfectly fresh fractures a depression may be felt 
between the pieces of bone. 
The prognosis is very unfavourable. Apart from the fact that 
reposition and retention are scarcely possible, it must be remembered 
that the sharp edges of the fragments may not only injure the posterior 
articular surface of the metacarpus, but may wound the flexor tendons 
which are worn through by the raw edges of the broken fragments; in 
addition, callus formation is difficult. 
Moller unsuccessfully treated a race-horse for several months, and 
found on post-mortem examination that the broken pieces had not 
united, and that the condition was substantially as above described. 
Field claims to have seen recovery follow longitudinal fracture of both 
sesamoid bones. On account of the great pain accompanying fracture, 
excessive volar (upright pastern) or dorsal flexion (oblique pastern) may 
later result. The first occurs when pain is great and the limb is rested 
for a long time; in other cases, as when pain is slight and weight is 
placed on the foot during recovery, excessive dorsal flexion results. 
Restoration of normal position and of usefulness being very rare, 
treatment is only justifiable in valuable breeding animals. 
Treatment. If treatment is to be attempted, the pastern-joint must 
be fixed in a position of moderate volar flexion by a plaster or strong linen 
bandage. Complete rest is necessary. Light horses, which have no 
difficulty in lying down and rising, do best on a soft bed ; other patients 
must be slung. 
YIL—SESAMOID LAMENESS. 
In solipeds, both the anterior articulatory surface of the sesamoid 
bones in contact with the metacarpus and the posterior surface over 
which the flexor tendons glide are often the seat of acute or chronic 
s s 
v.s. 
