600 
FRACTURES OF THE PHALANGES. 
of both front pastern bones in a mare. "Whether a peculiar predisposi¬ 
tion existed, or whether the cause was the sudden strain thrown on the 
still intact bone in consequence of the first fracture, could not, of course, 
be decided. Tuson, in the above-described case, found a want of inorganic 
substances in the fractured os suffraginis, but, somewhat characteristic¬ 
ally, gives no particulars of any analysis. In solipeds generally, and 
race-horses in particular, fissure of the os suffraginis is not infrequent. 
It was first noted in England, and Robertson and Williams described 
split pastern as quite a common occurrence. The condition is some¬ 
times overlooked, being mistaken for strain of the joint. Prolonged 
rest in the stable seems to favour its occurrence; many of the cases 
of multiple fracture, i.e., fracture of the pastern in more than one limb, 
were seen in horses which had just returned to work after long idleness. 
Peters made a series of observations, and explained why fissures of the 
os suffraginis almost always start from the middle depression (figs. 223, 
224, 225). According to his view, the split is produced by the promi¬ 
nence on the lower articular surface of the metacarpus at a time when 
weight is unequally distributed over the two articular surfaces of the 
pastern lying on either side of it. Violent rotary movements of the 
supporting limb act similarly, and explain why fissures follow sudden 
turning on the fore limbs. Sometimes the split extends through the 
entire bone as far as its lower margin, sometimes it passes towards one 
side. Not infrequently it is very short, and ends close below the upper 
articular surface, and is followed by periostitis and the production of an 
exostosis (fig. 224). 
Transverse fractures are also common in the horse, and affect some¬ 
times the upper, more frequently the lower, end of the os suffraginis. 
They likewise result from unequal distribution of pressure during slips. 
In one case Moller was able to detect during life that the inner border 
of the upper articular surface had been broken away by the violent pull 
of the internal lateral ligament, the outer border by the pressure of the 
metacarpus (fig. 226). Cases of transverse fracture, i.e., cases where 
the fracture started from the external lateral ligament and extended to 
a varying distance downwards (fig. 227), are not uncommon. That 
figured had been caused by suddenly throwing the horse on his haunches. 
Comminuted fractures of the os suffraginis are sometimes seen. Johne 
saw a transverse fracture unite in eight weeks without much callus 
formation; Dressier found a race-horse’s pastern broken into nineteen 
pieces; Bonnard counted thirty-four pieces in a similar case. 
In complete fractures diagnosis is seldom difficult, on account of 
there generally being some crepitation. When the lateral prominences 
of the bone are broken off, the fetlock-joint shows abnormal lateral 
mobility. On the other hand, careful examination is required to detect 
