a. Inefficient relief of lateral tension. Of late years I have become more than ever convinced of the paramount importance of the use of free incisions, and also that the vascular supply of the palate is amply sufficient to allow of these being made without any danger of sloughing, or of hindering primary union. That sloughing has occurred in the practice of others is undoubted; but this is more likely to have been due to a septic contamination and bruising of the tissues than to the extent of the incisions. I would again refer my readers to what has been already written ([p. 118]) as to the separation of the palatal tissues from the hamular process, and the complete detachment of the muco-periosteal flaps from the point of junction of the hard palate with the soft, where the tissue is thinner than elsewhere.
b. Defective paring of the edges of the cleft. This probably occurs from want of skill on the part of the surgeon, who fails to remove in one strip the mucous membrane from the margins.
c. Bruising of the edges from careless sponging, or rough manipulation with clumsy instruments. This is particularly liable to occur if the edges are pared prior to the detachment of the muco-periosteal flaps, in accordance with the mistaken directions given in many text-books.
d. Inaccurate coaptation of the edges of the wound, caused either by the stitches not being inserted at exactly opposite points on either side of the cleft, or by bringing the edges together too loosely, or so tightly that they are curled in.
e. Incomplete division of the levator palati will possibly explain some cases of non-union of the soft palate.
f. Want of careful supervision after the operation, and unsuitable food.
g. The occasional occurrence of uncontrollable vomiting or excessive hæmorrhage.
The most frequent situation of defective union is at the point of junction of the hard and soft palate; the tissue here is extremely thin, and laceration is liable to occur during the detaching process.
The apex of the cleft is another likely spot where union may fail; here from rigidity of the tissues accurate apposition is rendered difficult and sometimes impossible, particularly when the deformity is associated with alveolar cleft.