in osseous
ankylosis the shadow of the two bones is a continuous one. In fibrous as
contrasted with osseous ankylosis mobility may be elicited, although
only to a limited extent; while in osseous ankylosis the joint is
rigidly fixed, and attempts to move it are painless.

[Illustration: FIG. 155.--Osseous Ankylosis of Knee in the flexed
position following upon Tuberculous Arthritis.

(Anatomical Museum, University of Edinburgh.)]

The _treatment_ is influenced by the nature of the original lesion, the
variety of the ankylosis, and the attitude of the joint. When there is
restriction of movement due to fibrous adhesions, these may be elongated
or ruptured. Elongation of the adhesions may be effected by
manipulations, exercises, and the use of special forms of
apparatus--such as the application of weights to the limb. It may be
necessary to administer an anaesthetic before rupturing strong fibrous
adhesions, and this procedure must be carried out with caution, in view
of such risks as fracture of the bone--which is often rarefied--or
separation of an epiphysis. There is also the risk of fat embolism, and
of re-starting the original disease. The giving way of adhesions may be
attended with an audible crack; and the procedure is often followed by
considerable pain and effusion into the joint, which necessitate rest
for some days before exercises and manipulations can be resumed.

_Operative treatment_ may be called for in cases in which the bones are
closely bound to one another by fibrous or by osseous tissue.

_Arthrolysis_, which consists in opening the joint and dividing the
fibrous adhesions, is almost inevitably followed by their reunion.

_Arthroplasty._--Murphy of Chicago devised this operation for restoring
movement to an ankylosed joint. It consists in transplanting between the
bones a flap of fat-bearing tissue, from which a bursal cavity lined
with endothelium and containing a fluid rich in mucin is ultimately
formed.

Arthroplasty is most successful in ankylosis following upon injury; when
the ankylosis results from some infective condition such as tuberculosis
or gonorrhoea, it is liable to result in failure either because of a
fresh outbreak of the infection or because the ankylosis recurs.

When arthroplasty is impracticable, and a movable joint is desired--for
example at the elbow--a considerable amount of bone, and it may be also
of periosteum and capsular ligament, is resected to allow of the
fo