782 
DISEASES OF THE FOOT. 
caries; abscesses break in the flexure of the pastern, and the remaining 
portion of the flexor tendon becomes necrotic. In really grave cases 
where operation of this nature is necessary it is usually best to at once 
perform the operation implicating both sides of the frog. 
The preliminary precautions are as before mentioned. The foot 
should be extended by an assistant, and the plantar cushion divided 
transversely close to its base, with the double-edged curved knife already 
referred to. The section should be at an oblique angle with the general 
surface of the frog and in such a direction that when prolonged inwards 
it will meet the posterior edge of the navicular bone. The half-detached 
fragment of the plantar cushion is then grasped with forceps and freed 
from its lateral adhesions by two cuts along the lateral lacume of the 
frog. The deep face of the plantar cushion is in contact with the 
aponeurosis of the flexor tendon. 
L sing both hands to steady the knife, the operator now divides the 
aponeurotic portion of the flexor tendon transversely close to the 
posterior border of the navicular bone with one steady cut. The 
portion of the aponeurosis thus freed is next divided along the middle 
line from before backwards as far as the upper margin of the navicular 
bone, the fragments are reflected and each is carefully dissected free. 
Again grasping the knife with both hands, the operator makes a semi¬ 
circular sweeping cut along the edge of the semi-lunar crest, thus 
dividing the lower insertion of the aponeurosis into the os pedis. The 
fragments are then removed. 
The fibro-cartilage covering the lower surface of the navicular bone is 
next removed by the vigorous use of the curette. If the primary injury 
extend to the point of insertion of the plantar aponeurosis the terminal 
fibres of the tendon must be carefully removed and the semi-lunar crest 
curetted, caie being taken, however, not to open the joint between the 
navicular bone and the os pedis. If, however, the insertion of the 
aponeurosis is healthy the semi-lunar crest should not be touched; the 
fibrous layer which covers it soon becomes vascular, and granulates 
lapidly piovided it be protected from infection. Wherever gangrene, 
necrosis, or caries exists it is absolutely imperative to remove the whole 
of the diseased tissue, and, in fact, to encroach a little on the adjoining 
healthy paits. lo oveilook a fragment of diseased tissue is to risk the 
necessity for operating anew and under much more difficult conditions. 
The cavity is sponged with a 10 per cent, solution of chloride of zinc, 
rinsed with carbolic solution, powdered with iodoform, salol or calomel, 
fiimly packed with masses of tow, moistened with carbolic or sublimate, 
and a moist dressing applied over all. French operators touch any 
point in the wound which may appear likely to undergo degenerative 
