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 expres- 

 sion of opinion as to the precise starting-point of the affec- 

 tion, we shall describe the pathological changes occurring in 

 navicular disease as noted in (1) the bursa, (2) the carti- 

 lage, (3) 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 tume- 

 faction, owing to its infiltration with inflammatory exudate. 

 The portion covering the hyaline cartilage of the navicular 

 bone has lost its peculiar 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 

 •is too late to meet with this condition. The disease has 



* Percival's ' Hippopathology,' vol. iv., p. i32. 



