SINUS AND FISTULA

#Sinus.#--A sinus is a track leading from a focus of suppuration to a
cutaneous or mucous surface. It usually represents the path by which the
discharge escapes from an abscess cavity that has been prevented from
closing completely, either from mechanical causes or from the persistent
formation of discharge which must find an exit. A sinus is lined by
granulation tissue, and when it is of long standing the opening may be
dragged below the level of the surrounding skin by contraction of the
scar tissue around it. As a sinus will persist until the obstacle to
closure of the original abscess is removed, it is necessary that this
should be sought for. It may be a foreign body, such as a piece of dead
bone, an infected ligature, or a bullet, acting mechanically or by
keeping up discharge, and if the body is removed the sinus usually
heals. The presence of a foreign body is often suggested by a mass of
redundant granulations at the mouth of the sinus. If a sinus passes
through a muscle, the repeated contractions tend to prevent healing
until the muscle is kept at rest by a splint, or put out of action by
division of its fibres. The sinuses associated with empyema are
prevented from healing by the rigidity of the chest wall, and will only
close after an operation which admits of the cavity being obliterated.
In any case it is necessary to disinfect the track, and, it may be, to
remove the unhealthy granulations lining it, by means of the sharp
spoon, or to excise it bodily. To encourage healing from the bottom the
cavity should be packed with bismuth or iodoform gauze. The healing of
long and tortuous sinuses is often hastened by the injection of Beck's
bismuth paste (p. 145). If disfigurement is likely to follow from
cicatricial contraction--for example, in a sinus over the lower jaw
associated with a carious tooth--the sinus should be excised and the raw