False angular ankylosis of knee presents itself in numerous grades of severity, as described p. 12: the articulation may, from the previous disease, have undergone the smallest appreciable injury in structure and function; or the greatest amount of disorganisation, ulceration, adhesions, cicatrices, and luxation, compatible with remaining motion, may be present. The amount of contraction of the limb may vary from a few degrees, the sole being scarcely raised from the ground; or it may be so considerable that the heel almost touches the nates. In the majority of cases, the knee is flexed less than to a right angle, as at fig. 7; sometimes it does not exceed

FIG 7.

False angular ankylosis of right knee, from acute inflammation occurring as a sequela of puerperal fever. Slight outward rotation of leg exists, and the patella is applied to internal edge of outer condyle (see Cases).

that represented fig. 10, locomotion being frequently in such cases impossible, except with the aid of crutch and stick, or raised shoe; or it may reach the degree shewn fig. 8. The

greatest contraction is usually produced by acute inflammations of the articulation. Artificial supports beneath the knee, or the use of crutches, become then indispensable to locomotion.*

FIG. 8.

Incomplete angular ankylosis of knee, from phlegmonous erysipelas of entire limb (see Cases).

The degree of muscular shortening corresponds with the amount of the contraction. The tendons of the biceps and those of the semimembranosus and semitendinosus muscles are tense when extension is attempted. Sometimes the biceps appears alone contracted; but, in such cases, I have usually found section of the inner hamstrings necessary to complete the restoration. In false angular ankylosis of many years' duration, the lower portion of the vastus externus, and the portion of the fascia lata with which it is connected, are much contracted, and even the sartorius and gracilis tendons.

Emaciation and wasting of the bones, more particularly of the thigh, accompany every case of false knee-ankylosis. Occasionally some contraction of the gastrocnemii, and other flexors of the foot, coexists. The degree of motion remaining

* I have in my possession, as trophies of successful cure of long-standing ankylosis, a cabinet of wooden legs and crutches, which have been thrown aside by different individuals.

in partial knee-ankylosis is variable: in some cases in which the contraction habitually amounts to 70° or 90°, the limb admits of slow extension by pressure, and reduction of the contraction 20° or 30°. The kind of resistance felt on attempting to make extension may be termed elastic. Sometimes free motion within a limited range exists, a sudden stop to further movement being perceptible to the patient and to the hand of the practitioner. Occasionally the knee cannot be extended beyond a right angle, but freely admits flexion, so that the heel may be approximated to the nates. In many cases, however, there is no perceptible flexion or extension, the joint being truly stiff: here the question of the existence of true ankylosis arises. The certainty of absence of osseous union between the tibia and femur, or between the patella and either of those bones, can only be determined by the most accurate investigation. If the patella be free, or merely united by membranous or ligamentous tissues, some slight motion on its perpendicular axis may be discovered; one of its edges, more commonly the inner, may be depressed. A person endowed with an accurate sense of touch may feel a slight movement of the edges of the tibia and femur where they are applied to each other.

In addition to these means, the practitioner will observe whether, on endeavouring to extend the limb, the hamstring muscles be rendered tense. Caution is necessary when resorting to this source of diagnosis, lest the voluntary tension of the muscles by the patient be mistaken for that maintained by the attempt to straighten the limb. The patient's mind. should be diverted during the examination; and it should be noted whether the tension and relaxation of the tendons be really produced by the alternate extension and relaxation of the limb effected by the hand of the practitioner. I have already alluded to the production of pain on the contracted and uncontracted sides of the member, and the relative value

of the information derived therefrom (p. 28). The external configuration of the knee in false angular ankylosis varies: the joint may be rigidly flexed, the form not differing from that of the sound knee similarly flexed. This is often the case in ankylosis resulting from phlegmon affecting the entire limb (as at fig. 8), or after rheumatic inflammation of the joint; whereas, in other instances, especially after strumous and other forms of synovitis, in which softening and disorganisation of ligaments have taken place, the muscles have not simply contracted the articulation, but they have likewise altered the relation of the articular surfaces, and occasioned partial luxation and deformity, as in the following drawings.

FIGS. 9 and 10.

b

Front and lateral views of stiff knee-joint, from chronic (strumous) disease, excited by general debility, consequent on an attack of fever (see Cases).

The displacement (see figs. 4, 5, 9, 10) invariably consists of a dragging backward of the head of the tibia from the

anterior and inferior part of the articulating surface of the condyles of the femur by the continued action of the hamstring muscles, and is increased by the rotation outwardly of the head of the tibia, effected by the more powerful action of the biceps, favoured probably by the peculiar arrangement of the crucial ligaments, and sometimes by a cause mentioned page 20. This outward rotation of the tibia is accompanied with eversion of the leg, both of which are represented figs. 9, 10. The patella and its ligament are abnormally placed on the external condyle. The conjoint phenomenon of displacement, rotation, and eversion of tibia exists in different degrees: it may be slight, as at fig. 7; or almost complete dislocation of the tibia may be present, and even the anterior surface of the tibia be applied to the posterior part of the femoral condyles, and the utmost deformity result (see Cases).

Large indented cicatrices, which are often present in false ankylosis of knee, are commonly situated on the outer and posterior surface of the articulation. Sometimes, where the ankylosis has arisen from strumous disease of the articulation, cicatrices are observed on the front and inner side of the tibia and inner condyle (see Cases).

The next morbid condition which complicates false ankylosis of knee produced by disease is ossification of the patella to the outer condyle,* on which it then rests; or to the tibia, by means of ligamentum patellæ, which in such cases has become ossified. I have not found presumed ossification of the patella to the condyles an insuperable objection to straightening the knee, but it at all times constitutes an unfavourable complication-it precludes the possibility of restoring the functions of the extensor muscles and voluntary extension of the joint by the patient. Ossification of patella to tibia through the intervention of ossific deposit in ligamentum pa

*I have met with ossification of patella to internal condyle. The cause of the ankylosis was fracture, extending into the joint.