To differentiate by manipulation between muscular fixation and ankylosis, it may be necessary to anaesthetise the patient.  The nature and extent of ankylosis may be learned by skiagraphy; 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 formation of a false joint.

When bony ankylosis has occurred with the joint in an undesirable attitude—­for example flexion at the hip or knee—­it can sometimes be remedied by osteotomy or by a wedge-shaped resection of the bone, with or without such additional division of the contracted soft parts as will permit of the limb being placed in the attitude desired.