attacks the knee joint more frequently than any other, and likewise why the disease is more frequently observed in childhood than in adult age: and therefore need not recur to that subject.

I shall now confine my remarks to the discussion of some features that characterize the process under consideration.

One of these points is the extraordinary slow advance of the disease. Some authors think that a low grade of nutrition of the structures primarily involved, offers an acceptable explanation. On close reflection we shall find this view inadmissable, and contradictory to analogy. Nutrition in childhood is more exuberant than at any later period. In the former, maintenance is not the only object of the nutritive process; it is enhanced by growth and developement, demanding more ready supply, and meeting with the most elastic condition of the vascular carriers of that supply. In these advantages the infantile skeleton participates to a higher degree than the other systems of the organism.

Hence from a physiological point of view, we have to reject the advanced theory.

In questioning analogy, we notice facts which demonstrate beyond a shadow of doubt, the prolific character of nutrition in the osseous system of children. Fractures consolidate more rapidly with them than with adults; artificial joints are scarcely ever observed during the period of evolution; if periostitis has laid bare the bone of a child, exfoliation rapidly ensues, and sequestra form much more quickly than at a later period. These facts coincide with the experiments of Flourent and Wagner, and dispose effectually of the before mentioned hypothesis.

In all those cases of white swelling, that I have had the opportunity of anatomically investigating, and they have been numerous, I have observed that there is always, in one or the other condyle, an insular disintegration of the cancellated structure, in which sometimes a small sequestrum is imbedded. Under the microscope scarcely any trace of the vanquished structure can be discerned. The chief element is fat. But in the neighbourhood of this pathological focus, hyperaemia, traces of fungoid granulations, and osteoporosis are noticed. This condition explains satisfactorily, the proximate cause of the pathological changes inconsis tent with the active process of ostitis. In some rare instances, however, the healthy portion of the bone surrounds the disintegrated isle with a sclerotic capsule, by which the affected portion becomes, as it were, isolated and rendered innocuous, in a similar manner as foreign bodies en. capsule. This pathological condition may not cover all cases which pass under the name of tumor albus, but certainly this is the most prevalent.

spasms

There is a specimen in my collection, of the lower third of a femur of a young girl not exceeding fifteen years of age. She was admitted to the Brooklyn Medical and Surgical Institute, with all the symptoms of white swelling, comprising the articulation and peri-articular structures; the swelling however likewise involved a portion of the femur. The local disturbances were as intense as were the nocturnal pains, and the of the flexor muscles. The knee was of course drawn to a right angle. From the history of the case, and the clinical character of the disease, circumscribed osteomyelitis, with its termination in abscess, was diagnosed and in view of her reduced constitution, and the copious discharge of matter from the neighbourhood of the joint, amputation was deemed expedient.

The condition of the specimen fully confirmed the diagnosis. There is a large pyogenic cavity at the lower end of the femur, which opens at the posterior aspect of the bone, by an irregular aperture not less than an inch and a half in diameter; in the circumference of which, the periosteum is raised up, and its internal surface covered with new bone. The epiphysis is somewhat loosened from its attachment, and in time would have become separated.

The original focus of the diesease had been obviously limited to the cancellated structure, and rather remote from the joint, but its consecutive effects had extended over the joint, and involved its soft surroundings. There may be still other exceptions from the anatomical prototype, but their numerical proportions scarcely affect the statistics.

The adherents of the tubercular theory, may rejoice at this pathological admission of mine, of those insular and circumscribed pathological foci, which they may claim as bona fide evidence of tubercular deposit.

I hold however, that pathological detritus, limited to an isolated place, cannot in the eyes of competent judges, pass as tubercle.

If the desease is permitted to spread, it eventuates in perforation of the articular cavity; the formation of external abscesses and fistulous tracts, and the more obstacles the discharge has, the more periosteum will be destroyed, and the bone corroded on its surface.

The protracted development of these phases extends over many months, and often additional injuries are required to accomplish so extensive disintegration.

A lull of all symptoms, is often observed in the like cases, to be followed by new exacerbations. A goodly number recover spontaneously, or by appropriate treatment. These recoveries happen not rarely at the period of puberty, at which time the mode of nutrition of the epiphyses becomes perfected.

In analysing the gradual development of this disease, its preceding cause, (traumatic injuries); the comparative moderate effects upon the integrity of the adjacent osseous structure; we find a more passive pathological condition, a direct necrobiosis of the affected structure, more from want of proper maintenance, than from active and progressive disease. When active symptoms subsequently set in, they are the efforts of the vis medicatrix natura to eliminate the detritus foreign to the integrity of the bone. Frequently the detritus becomes absorbed, or pervaded with calcareous elements, and thus recovery is attained.

This gradual change of the osseous structure and annihilation of its nervous and vascular endowments, though limited in extent, renders it intelligible why so little pain is experienced by the patient, during the first disintegrating period of the disease. The intense pain that is at a later period superinduced, is evidently connected with the peripheral and active process of osteitis arising in the circumference of the focus. The original disease has nothing to do with it.

The appearance of nocturnal pain constitutes a serious complication and indicates the commencement of suppuration.

The contraction of the biceps muscle is quite common and the result of reflected spasm. The leg is thus held in an angular position to the thigh, and most usually rotated on its longitudinal axis, with eversion of the toes. This position goes pari passu, with an anatomical derange ment of the joint itself. The patella rides upon the external condyle of the femur, and is generally adherent; the internal condyle of the tibia projects in front, whilst the external one recedes.

The contraction of the biceps is exclusively accountable for this malposition, for at a certain angle it acts as a rotator, when not counteracted by the simultaneous contraction of the internal hamstrings.

I have but lately exhibited to the New York Pathological Society a specimen of this kind, and the action of the biceps, is so undeniably demonstrated, that there is no more room for further speculation to account for the symptoms.

For a long time the mobility of the affected joint remains, if not impeded by the contraction, but when synovitis is superinduced to the original affection, the joint may become obliterated by fibrous adhesions between the articular faces, which may still more impede the mobility, but rarely are there osteophytes passing from one bone to the other, depriving the joint of all vestige of motion. True bony anchylosis is of very rare occurrence, and much more the consequence of penetrating wounds of the joint, and high graded synovitis, than of this form of disease.

Whether the disease originates in the synovial membrane, in the crucial ligaments, in the periosteum, or the epiphysis of the joint, the symptoms apertaining to each of them respectively, will be so blended in their advanced course, as to render diagnostic discrimination almost impossible, leaving the previous history as the only guide.

The pathological conditions of joint diseases vary but little, when suppuration, burrowing of pus, has been going on, and the bones have been disintegrated for any length of time; the symptoms attending those conditions are almost uniform in all such cases. The competent and experienced surgeon may yet recognize the pathogenesis of the original disease, but novices rarely realize differences so indistinct and subtle. Thus. in caries of the joint emanating from synovitis, the articular surfaces are more generally denuded of their respective cartilaginous coverings, but the osteo-porosis does not much exceed the surface; the crucial ligaments are but partially destroyed; the semilunar cartilages partly disintegrated, discolored, and mostly detached. On moving the articulation, crepitus is discernible. If, however, the bone has been the starting point of the disease, the caries of the articular surface is generally restricted to the originally affected locality; and the cartilage is there and thereabout disintegrated. The crucial ligaments are mostly destroyed in toto, and crepitus is less distinct.

The clinical character of hip disease will now demand attention, on account of some peculiarities in its manifestations. Morbus coxarius is about as good a term as could be chosen and certainly more appropriate than "coxalgia" which applies solely to the pain of the affection.

The first stage of this lesion materially conforms with the same stage of the affections of other joints. The only symptom requiring special mention, is limping. It is most noticeable in the morning, less during the day, and least towards evening; most conspicuous after great exertion, and sometimes absent after a day of complete rest. The duration of this period is variable; repeated accidents and the continuous use of the affected extremity may shorten, and constant rest prolong it.

The so characteristic pain at the knee, may already make its appearance at this stage, but if so, there will be likewise indications of retracted muscles, with which this symptom appears conjointly. This pain has often confounded the diagnosis of the less experienced, without any need; for you may press and squeeze the knee joint as you please, without the slightest increase of that pain, whereas the pressure upon, and movement of the hip joint will aggravate it. The progress of the malady may, at this juncture be arrested, and the patient relieved from further trouble.

The second Stage is characterized by elongation, abduction, eversion and slight flexion of the affected limb at the hip, with lowering of the pelvis, flattening of the gluteal region, sinking of the gluteal fold, and an inclination of the internațal fissure, at, and towards the affected side. The mobility of the joint may either be impeded, or entirely suspended. Adduction is generally impossible.

For the purpose of locomotion, the patient brings the lumbar portion of the spine and the other hip joint into play; thereby easily deceiving the inexperienced observer. In the erect posture the spine exhibits a single curve, of which the convexity corresponds with the seat of trouble. The superior spinous process of the ilium, is depressed when compared with that of the other side, and the healthy member is adducted in proportion to the malposition of its afflicted fellow. In walking, the patient places the latter forward and outward, and drags the other limb after it in a rather diagonal direction. All these symptoms more or less complete, can be ascertained by undressing the patient; dropping a plummet line from the occipital protuberance, walking, and by careful examination in the horizontal posture. If the patient sits down in such a manner as to accommodate the affected member, both pelvis and spine assume normal relations, thus proving that the elongation of the limb does not depend on the lateral declivity of the pelvis, as *Gross asserts.

The chief or proximate cause of the entire group of symptoms rests with the immobility of the joint and the fixed adducted position of the extremity. In imitating them we produce the very same effect.

There can be no doubt that the elongation is but apparent, and not real, as the late professor Rust of Berlin, claims. Nor is there any enlargement of the head of the femur, from either tuberculosis or other causes, to which he ascribes the actual elongation. The sole source of the symptom is hydraulic pressure from existing intra-articular effusions; I was led to this view from the analogous position of the femur and the immobility of the joint produced by experimental injection. Acting on this supposition, I have succeeded in substantiating the correctness of my opinion, by paracenteses of the articular cavity. The removal of the intra-articular fluid was followed immediately by returning mobility and the correction of the malposition. This point is consequently settled by demonstrable evidence.

With the apparent elongation of the limb, the structural pain gradually increases, and the reflex symptoms rapidly rise to an intense degree. The nocturnal pains, in this period are more violent and torturing than

*Gross' "Practical Observations" Philadelphia 1859.