NAVICULARTHRITIS. 173 



Once commenced, ulceration spreads down the sides of the navi- 

 cular crest, giving the formerly smooth and shining surfaces of the 

 bone the patchy eroded aspect which has been well characterized 

 as looking like worm-eaten ; at the same time that, owing to the ul- 

 ceration, and to the attenuation as well, of other parts of the articu- 

 lar cartilage, discolouration is very visible : the surfaces having, in 

 exchange for their humid and shining aspect, taken on them a 

 dead and dingy brownish tinge. 



Brauell, whose observations on this point are worth our record- 

 ing, says, — " the consequences of inflammation of the navicular 

 bone are, in all cases, a diminution in its magnitude ; and caries 

 is the primary cause of this. The caries is either deep or super- 

 ficial, and is found invading one or more points, particularly the crest 

 (or transverse eminence) of the navicular bone and its lateral de- 

 pressions. Prior to the development of the caries, little eminences 

 about the size of millet seeds are discoverable upon the surface : 

 after maceration they look like so many exostoses." — " As the 

 caries increases in depth and breadth, the holes in the bone enlarge, 

 sometimes attaining a capacity to hold a hazel nut. In this porous 

 condition the bone is exceeding liable to fracture, an accident the 

 more likely to happen from the caries being accompanied by fria- 

 bility of the substance of the bone." — "And, while the navicular 

 bone is experiencing loss of substance on the one side, it is very 

 seldom that any new- formed osseous matter is deposited upon the 

 opposite (articulatory) surface. It is around the borders, posterior, 

 superior, and inferior, where such deposits are generally found. 

 And it is the union which takes place between such incrustations 

 shooting out from the posterior and inferior borders of the navicu- 

 lar bone, and similar spicules issuing from the back part of the 

 coffin-bone, that constitutes anchylosis between one and the other." 



Adhesion. — At this period of the disease, the synovial covering 

 of the perforans tendon being likewise in a state of exulceration, 

 adhesion is very likely to take place between it and the navicular 

 bone ; though in a case where ulceration of the cartilages prevails 

 this is not so likely to happen as in one wherein the primary ul- 

 cerative action in the membrane is immediately succeeded by a 

 graiiulative or adhesive process. And it is most usual for this ad- 



