the thigh can be permanently straightened, so that the patient can partially place the foot on the ground,-or if, instead of walking with the knee inverted, and not without the assistance of a boot raised four or five inches, locomotion can be effected with a shoe raised at the heel but little more than an ordinary boot, the patient's gratitude will amply repay the practitioner for the trouble he has experienced in the treatment of a case of no very encouraging nature (see Cases).

ANKYLOSIS OF THE KNEE.

1

The great frequency of ankylosis of the knee, and the comparative facility with which, owing to the proximity of the articular tissues to the surface, pathological changes may be studied in this joint, induced me, in the remarks on ankylosis in general, pp. 5-13, to refer to this affection for the illustration of ankylosis of other articulations. Many observations which belong properly to this place will, therefore, be found in that section. The causes and varieties of ankylosis of the knee are there enumerated, and its morbid anatomy has been in great measure anticipated. Ankylosis of the knee may be straight or angular, complete or partial.

Straight partial (false) ankylosis of the knee occurs much less frequently than the angular, and is more often the result of mechanical violence or of acute inflammation, as the rheumatic, than of chronic disease. I have, however, been consulted in one case in which this form of ankylosis was produced by strumous disease of the head and shaft of the femur. The motion of the joint was, in this instance, extremely limited, from the deposition of osseous matter in the popliteal region. A lamina of bone, some inches in length, resembling in form an ivory paper-knife, extended from the upper and posterior part of the tibia towards the junction of the lower and middle third of the femur, somewhat similar to a preparation in the museum of the Royal College of Surgeons, London,

but not ossified with the femur, as in the preparation in question. The patient could execute flexion to the amount of 15°, by acting on the flexor muscles of the knee, considerable resistance to further bending being experienced in the tendon of the quadriceps femoris. Manual efforts to bend the joint caused a yielding to the extent of a very few degrees, the principal impediment being the adventitious osseous deposit in the poplitea.

Little or no deformity accompanies partial straight ankylosis of the knee, except that arising from imperfect development or wasting of the muscles of the thigh. These offer occasionally a strong contrast with the powerful mass of the gastrocnemii, the energy and growth of which has been excited by the increased demands on their activity consequent on the stiffness of the knee. The leg commonly presents slight rotation outwardly, the toes being everted. In the act of walking, therefore, the foot more easily avoids inequalities on the surface of the ground.

Straight partial ankylosis is sometimes the result of imperfect cure of angular ankylosis, extension having been accomplished, but the joint remaining incapable of flexion. This may arise either from adhesion of the patella to the condyles of the femur (see Cases), or probably from an alteration in the position of the semilunar cartilages.

Treatment of straight partial ankylosis of the knee.—If slight, mechanical extension, manipulations according to the general principles already enumerated. Subcutaneous section of the tendon of the quadriceps femoris when indicated, or of the adhesions of patella to femur when membranous. I entertain no doubt of the utility and perfect safety of the last operation, under ordinary circumstances, in healthy constitutions; but I have never resorted to it, or recommended its performance, as patients affected with straight partial ankylosis of knee can walk with comparative ease, and it has con

sequently not appeared advisable to perform any operation that, by the remotest possibility, might produce articular inflammation, and endanger the limb. Although straight stiff knee does not prevent locomotion, it occasions great inconvenience in walking on uneven ground, ascending a hill or staircase. The great flexibility of the ankle to a certain extent relieves the discomfort from this cause; but the limb being, from the inflexibility of its most important joint, rendered relatively too long, it is felt continually in the way: patients

FIG. 6.

Complete straight ankylosis of knee, exhibiting ossification of patella

to external condyle, and the ordinary displacement of the tibia. Fusion of the femur and tibia.

eagerly embrace the hope of obtaining a slight amount of flexion; and this may, in the majority of instances, be obtained by perseverance in mechanical means, manipulations, and frictions.

Complete, true or osseous, STRAIGHT ANKYLOSIS of the knee presents the same external characters as partial straight ankylosis, excepting that the immobility is now complete, firm osseous union having taken place between the femur and tibia. In this state of the articulation, the case must be considered incurable: it is, however, fortunate that it does not prevent active, although limited, use of the limb.

Cases, however, occur, in which, after inflammation, and the formation of membranous adhesions between the articular

surfaces, and incipient osseous deposits in those adhesions, the attention of the practitioner may be usefully directed to the attainment of a more favourable position of the member, and to the retention of a limited amount of mobility. It should be borne in mind, that a slightly-flexed position of the knee is preferable to an absolutely straight one, and that even mobility to the extent of a few degrees will greatly ameliorate the patient's condition. It does not, at first view, appear probable that any interference on the part of the medical attendant can arrest the deposit of calcareous spiculæ into the abnormal tissues of an articulation, and the production of a complete ankylosis. On the contrary, it is generally supposed that, whenever the organic crystallisation of the material circulating through the newly-organised adventitious tissues has commenced, no means which we possess can cause its cessation. It is, however, well known that, in a variety of instances in inorganic matter, crystallisation is prevented by continued motion of the molecules, in the same manner as coagulation of the human blood within the living frame is partly prevented by the continued motion to which it is subjected within the blood-vessels. Whether the opinion that these facts are applicable to the question under consideration be hypothetical or not, we should imagine that passive movements of the articulation would merely retard the process. I am able, notwithstanding, with some confidence to affirm, that this process of ossification or calcareous deposit may safely, permanently, and advantageously be interrupted, by frequently repeated gentle movements of the articulation. This statement is liable to the objection that, in the experiments made on the subject, it may be doubted whether conclusive evidence of the incipient calcareous deposit existed.* Surgeons entertain well-founded objections to movement of a recently inflamed articulation as a

See remarks on this subject by Dr. Barton in American Cyclopædia of Medical Science, article Ankylosis.

means of preventing ankylosis, the danger of reproduction of disease being, in incautious hands, great; but too limited a view of the nature of the previous disease, exaggerated fears of the danger of relapse, often indispose the practitioner to attempt restorative measures. It should be remembered that most local inflammatory affections require for their production and maintenance a morbid condition of the general frame, and that, during the continuance of the local disease, a beneficial change in the general health often ensues; so that those means which, at one stage of the affection, would have been ruinous to the articulation, may, at another, be safely applied. The condition of the general health should constitute an important guide in the determination of the propriety of endeavouring to restore the flexibility of a partially ankylosed limb. After severe traumatic injury, or rheumatic inflammation of a joint which has not terminated by resolution, but by one or other of the "terminations of inflammation," the system having been depleted, or the morbid predisposition removed, by proper regimen, or by antiphlogistic and other remedial agents, we may usually, within a few months, undertake the treatment of the resulting ankylosis; but after strumous disease of an articulation, it is prudent to wait a longer period, or until a favourable change in the diathesis of the individual has taken place, before active orthopaedic treatment is undertaken. Sometimes, in such cases, we may be compelled to wait even several years before attempting to restore the usefulness of the member.

False angular ankylosis of knee.-Few remarks in relation to morbid anatomy remain to be added to those contained in pages 13-26; but I shall again allude to the displacement of articular surfaces, which occurs so commonly in this deformity. The symptomatology, and the determination of remediable from irremediable cases of stiff knee-joint, constitute one of the most interesting subjects of orthopædy.