Cartilage.—When acute inflammation has existed in the synovial membrane or bones of the elbow-joint, the articular cartilages covering these will very frequently be found to have assumed, in patches, a dull yellow colour ; in the latter discoloured points the cartilage is soft ened, and a blunt probe slightly pressed will sink into its structure, and its subjacent surface will be found to be detached. A new vascular membrane having been interposed between the cartilage and the cancellous structure of the bone, this elevation and partial detachment of the articular cartilages from the heads of the hone, and interposition of a new organized mem brane, are probably the usual preludes to those other changes we notice. Thus sometimes a leaf or flap of the articular cartilage, adherent only by an edge, hangs into the cavity of the joint, and again fragments of this structure completely detached are found loose in the in terior of the articulation. In these instances there is reason to conjecture that the diseased action which detached the cartilage began on the surface of this structure contiguous to the bone. We have occasionally, however, evidence of ulcerative absorption having commenced on the free surface of the cartilage. The peculiar worm-eaten appearance which the surfaces of cartilages next the cavity of the joint occa sionally present, and which, wherever it exists, is considered by many pathologists to be the result of a process of ulceration which had be gun on the free surfaces of the articular carti lages, has been occasionally though rarely seen in the elbow-joint ; much more frequently in examining, elbow-joints which have been the seat of disease, the articular surfaces of the bones have been found extensively divested of their cartilages ; a few patches of them alone here and there remain ; and these, though apparently thinner than natural, are of their ordinary tex ture, and are firmly adherent to bone.
Such extensive removal of cartilage, which has exposed the cancelli of the heads of the bones, has generally been the result of some very violent attack of inflammation, which, no matter in what situation it had originated, ulti mately we find had not spared any of the tis sues entering into the formation of the articu lation.
Bone.—The elastic white swelling (which is one of the usual external signs of this articular caries when the bones of the elbow-joint are the seat of the affection) is always situated poste riorly, and gives a characteristic appearance and a rounded form to the back part of the elbow-joint, which cannot be mistaken nor misunderstood. The wasted appearance of the arm above and of the fore-arm below makes this swelling more conspicuous, and the whole limb remains habitually in the semiflexed posi tion, with the fore-arm somewhat prone ; every movement of the articulation causes the patient much pain. The disease, thus arrived at its second or third stage, may remain stationary for a time or terminate in an anchylosis of the bones; commonly, however, the morbid pro cess goes on. Luxation of one or both bones of the fore-arm occurs, symptomatic abscesses present themselves, and these after a time make their way to the surface, and discharge their contents through openings, sometimes near, and frequently at a distance from the joint; and thus, at length, we see formed direct outlets as well as sinuses and fistulous canals, which give exit to exhausting discharges. The pain and irritation attendant on the disease itself, added to all these, give rise to hectic fever, which too frequeotly nothing but the desperate measure of amputation will arrest. The disease, which
produces such serious consequences, often be gins very insidiously, either in the head of the radius and external condyle of the humerus, or in the trochlea of this bone and the great sig moid cavity of the ulna. When the disease begins at the radial side, the pain runs along the course of the musculo-spiral nerve, and there is a manifest swelling externally in the situation of the radio-humeral articulation : although there is even now a marked tendency in the fore-arm to remain in a semiflexed posi tion, still gentle flexion and limited extension are admissible ; but when the radius is pressed against the humerus, and a movement of rota tion at the same time is given to the fore-arm, much pain is complained of. The disease may go on, confining itself chiefly to the radial side of the elbow-joint through its first stage of pain and swelling ; through its second of effu sion of fluids and relaxation of the coronary and external lateral ligament; and, thirdly, to dislo cation backwards of the head of the radius, and even to suppuration and discharge of mat ter through an ulceration or slough of the inte guments.
When the caries has commenced in one of the opposed surfaces of the trochlea of the humerus or great sigmoid cavity of the ulna, the swelling and effusion are first noticed in ternally at the side of the olecranon and inter nal condyle. The pain extends to the wrist along the course of the ulnar nerve ; the fore arm is in this case also in a state of semi-. flexion, and any attempt to extend or increase the degree of flexion causes very severe pain, while, on the contrary, a movement of rotation of the fore-arm is permitted. If the disease pro ceeds, the great sigmoid cavity of the ulna be comes wider and deeper, and the humerus ad vances on the coronoid process ; the internal lateral ligaments are relaxed, and the triceps drags back the fore-arm, so that the olecranon process projects somewhat posteriorly, and there is a tendency to a displacement backwards.
Whether the disease has originated on the radial or ulnar side of the joint, it very generally spreads so as to involve the articular surfaces of the three bones, and now the disease, termed scrophulous white swelling, becomes fully esta blished, and is easily recognized by the usual signs. Besides dislocation backwards, either of the radius or of the ulna singly, or of both these bones together, lateral displacements of the bones of the fore-arm at the elbow have been noticed as a consequence of caries ; nor need we be surprised at such variety of posi tion being assumed by the bones, when inflam mation has softened the strong lateral ligaments and caused their ulceration. While the patient is confined to bed or to the horizontal posture, the mere position which is given to the fore-arm on the pillow will influence the direction of the displacement that will occur. We have seen, under such circumstances, complete late ral displacement of both bones of the fore-arm outwards. The internal condyle of the hume rus pressing against the integuments covering it had caused a round slough, through which the internal condyle of this hone protruded, while the rounded head of the radius had on the outer side caused a similar slough and ulceration of the integuments, through which the upper cup-like extremity of this bone had protruded.