432 DISEASES OF THE HORSE’S FOOT 
the bone are accompanied by well-marked lesions on its 
gliding or postero-inferior surface, and by evidences of an 
osteoplastic periostitis along its edges. 
That an osteoplastic periostitis has been in existence is 
Fic. 162.—A Foor witH THE Skat or NavicuLaR DIsEAsE 
EXPOSED. 
On the anterior surface of the perforans fibres of the tendon are seen 
to be torn away from their abnormal adhesion with the navicular 
bone, while others are seen to be still attached thereto. The 
surface of the navicular bone itself exhibits small defects in the 
bony substance, which have been brought about by a rarefactive 
ostitis. 
a, The perforans tendon cut through and reflected ; 8, the sole. 
witnessed by the appearance along the edges of the bone of 
numerous outgrowths of bone, termed osteophytes (see 
Fig. 163). 
The interosseous and postero-lateral ligaments of the 
