lint is worn for a period varying
from six to twelve months; before being discarded it may be left off
at night; it is ultimately replaced by a bandage.

[Illustration: FIG. 125.--Thomas' Knee Splint applied. Note extension
strapping applied to affected leg, and patten under sound foot.]

The indications for _operative treatment_ are: (1) marked symptoms of
destruction of the articular cartilages; (2) a deformed attitude
incapable of being rectified without operation; (3) a condition of the
general health which requires that the disease should be got rid of as
speedily as possible; (4) progress or persistence of the disease in
spite of conservative treatment. When there is no prospect of recovery
with a movable joint it is a waste of time and a possible source of
danger to persevere with conservative measures. Operation permits of
the disease being eradicated and the restoration of a useful limb
within a reasonable time, averaging from three to six months.

In adults, the operation consists in excising the joint; in children
the aim is to remove the diseased tissues without damaging the
epiphysial cartilages.

Amputation is performed when the disease has relapsed after excision
and there is persistent suppuration, and when life is threatened by
the occurrence of tuberculosis in the lungs or elsewhere.

#Treatment of Deformities resulting from Antecedent Diseases of the
Knee.#--Flexion is the commonest of these; when due to contracture of
the soft parts, these are either stretched by degrees, the limb being
encased in plaster after each sitting, or they are divided by open
dissection in the popliteal space. If there is fibrous or osseous
ankylosis, the choice lies between arthroplasty, the removal of a
wedge of bone which includes the joint, or, in patients who are still
growing, of a wedge from the femur above the level of the epiphysial
cartilage. Backward displacement of the tibia, genu recurvatum, and
genu valgum also require operative treatment.

OTHER DISEASES OF THE KNEE-JOINT

#Pyogenic diseases# result from infection through the blood stream,
from one of the adjacent bones, or from a penetrating wound of the
joint. The commoner types include the _synovitis_ associated with
disease in the adjacent bone, _acute arthritis of infants_, joint
suppuration in _pyaemia_, _pyogenic arthritis_ following upon
penetrating wounds, and the affections which result from _gonorrhoeal_
or _pneumococcal_ infection.

_T