DISEASES OF THE JOINTS 429 
commences in the interior of the navicular bone. Just as 
strenuously we find the editor of the journal in which the 
matter is being discussed, the late Mr. Fleming, asserting 
that the disease commences in the bursa.* Others, too, 
hold that the disease commences primarily in the tendon. 
Wedded to this view was the discoverer, Mr. Turner, of 
Croydon; while Percival commits himself to the statement 
that it is either the central ridge or the postero-inferior 
surface of the navicular bone, or the opposed concavity in 
the perforans tendon, that shows the earliest signs of the 
disease. The observations made by Dr. Brauell, the first 
Continental writer to fully describe the disease, led him to 
the statement that neither the bone nor the bursa was the 
invariable starting-point of the trouble, but that usually it 
commenced in inflammation of the bursa itself, 
Without, therefore, committing ourselves to an expression 
of opinion as to the precise starting-point of the affection, 
we shall describe the pathological changes occurring in 
navicular disease as noted in (1) the bursa, (2) the carti- 
lage, (8) the tendon, and (4) the bone. 
1. Changes in the Bursa.—Upon the internal surface of 
the bursal membrane is first noticed a slight inflammatory 
hyperemia, accompanied by more or less swelling and 
tumefaction, owing to its infiltration with inflammatory 
exudate. The portion covering the hyaline cartilage of the 
navicular bone has lost its pecular pearl-blue shimmer, and 
become a dirty yellow. 
Remembering that the bursal membrane is a synovia- 
secreting one, and bearing in mind what happens in 
ordinary synovitis and arthritis (with which, of course, 
this may be very closely compared), we shall first expect 
changes in the bursal contents. It is highly probable, 
though difficult of proof, that in the very early stages the 
chronic inflammatory stimulus has the effect of increasing 
the flow of synovia. In every case, however, where it can 
with any certainty be said that navicular disease exists, it 
ig too late to meet with this condition. The disease has 
* Percival’s ‘ Hippopathology,’ vol. iv., p. 182. 
