NAVICULAR DISEASE. 
035 
Opinions are divided as to the point of origin of the disease. Turner 
places it in that portion of the bursa surrounding the tendon, Fambach 
considers the disease starts from rupture of fasciculi in the tendon. 
Schrader and others locate the primary disease in the gliding surface 
of the navicular bone. Brauell, however, maintains that the point of 
origin is not constant, and that sometimes one, sometimes the other 
tissue first becomes affected. The fact that the perforans tendon is 
always found diseased does not prove that the first changes occur in it, 
for immediately the surface of the navicular bone becomes roughened 
the tendon is endangered. The gliding surface of the navicular bone 
seems to be the commonest point of origin. Both the course and 
character of the process support this view. Little spots no larger than 
a millet-seed are to be found here, generally about the centre of the 
middle elevated portion, over which the cartilage appears coloured 
(figs. 248 and 249). Smith views these as calcareous deposits, but 
microscopic examination reveals the same conditions as in arthritis 
Fig. 249. — Navicular bone in chronic navicular disease (after Brauell). 
chronica deformans, i.e., proliferation of cartilage cells, with fibrillation 
of the intercellular substance. The cartilage thus altered loses its 
consistence and becomes eroded (fig. 249). 
As soon as the substance of the bone is attacked, granulations form, 
causing destruction of neighbouring portions of cartilage and of bone. 
Rarefying ostitis sets in; the compact tissue, normally of a yellowish- 
white, assumes a reddish colour, and disappears more and more in con¬ 
sequence of increasing proliferation of the medullary tissue. The bone 
may thus he so much weakened as to readily fracture under pressure of 
the tendon. Smith states having seen, in certain cases, change in the 
compact tissue precede that in the cartilage: this is more frequent 
where both feet suffer. As a rule, these peculiar osteophytes, which 
resemble those of arthritis deformans, and appear as though poured out 
on the surface, can be found on the margins of the navicular bone, and 
especially on the upper margin, wdiere the bursa extends from the tendon 
on to the bone. The ligaments of the navicular bone become thickened, 
and sometimes ossified. The upper surface of the bone, which contributes 
to the formation of the coffin-joint, is never thus affected. 
