When the second period has commenced, and the soft parts are excited into irritation, if opportunities occur of examining the inte rior of the bones, they will be found to be sof tened and easily penetrated by a knife. The synovial membrane contains an unusual quan tity of fluid, and the bones will undergo fur ther changes as the disease grows worse. These structures become still softer, their cancellous structure is found filled with a yellowish cheese like matter. The bones, which in the first pe riod were in an hyperxmic condition, are now found to be less vascular, and portions even become necrosed, so that it is not un common in advanced cases to find in the in terior of the joint portions of dead bone. • In these cases the spongy portion of the bones seems so altered in structure as to appear half dissolved, and to contain a sanious and foetid matter in its substance. The periosteum in vesting the bones in the neighbourhood of the diseased knee is very much thickened and easily detached. It is surprising to what an extent this strumous disease may have ad vanced in the bones and in the external parts around the joints while the synovial structures and cartilages remain but partially engaged. The writer has lately been compelled to ampu tate a thigh for this disease of the knee in con sequence of the constitutional symptoms which it excited in the system. In this case he dis covered that while the bones and soft parts externally were far advanced in the second stage of the disease, the synovial membrane and cartilages were perfectly natural. When, however, the disease has advanced far, and the fistulous orifices are found to communi cate with the interior of the joint, we find that the synovial membrane presents appear ances of morbid action having gone on in it, and when the puriform fluid contained in it is wiped away, that the surface of this mem brane, instead of being white, is red and vil bons, and much like mucous membrane in a high state of inflammation. We can frequently ascertain that this membrane has superadded to it layers of newly deposited lymph, which have become highly organized. Mr. Russell says, that in his dissections of white swelling of the knee, he has found the inside of the synovial membrane covered with a layer of a soft substance, of a pale yellowish colour, and semi transparent; that this substance was nearly one-eighth of an inch in thickness, softer in its inner concave surface, and firmer on the outer convex part, where it adhered to the inside of the synovial capsule of the joint with a con siderable degree of firmness. In many places he observed on it a very beautiful plexus of vessels; and at the interstices between the sur face of the femur and tibia, he states that he generally found an appendage full of blood vessels which had insinuated itself to the dis tance of nearly half an inch. It very fre quently happens that the cartilages and crucial ligaments are completely concealed from our view by a membrane, in some places of one quarter or even one-half of an inch in thick ness, presenting a loose cellular structure, highly vascular, occupying the intervals be tween the condyles, and hanging into the in terior of the joint; and we have usually found this newly-formed structure to be superadded to the original synovial membrane, and to establish adhesions between the bones of the articulation, and we find bands of organized lymph stretching from the femur to the tibia. When this condition of the synovial membrane existed, we have usually found the cartilages remaining; but in other cases the synovial membrane itself has been found to be but little altered; and yet the cartilages have been re moved partially or completely, the porous sub stance of the bone having been found exposed, or covered by recent deposits of soft pultaceous lymph.
Such are the organic changes which usu ally produce white swellings. These changes present numerous varieties, but it is sufficient to notice the principal ones, and to observe that there are scarcely two patients in whom they are perfectly alike.
Sir Benjamin Brodie, in his work on the joints, has remarked that when acute inflam mation attacks the shaft of a cylindrical bone and the periosteum covering it, the disease is usually limited by the epiphysis, so that, not ' withstanding the extensive abscesses and exfo liations which frequently ensue, the neighbour ing joints are not affected by it. Although we have seen numerous specimens proving the ge neral truth of this observation, yet on the other hand we have witnessed exceptions to it: in deed Sir Benjamin Brodie has further observed that a few instances occur in which acute in flammation attacks the epiphysis itself, termi nating also in exfoliations, &c. more or less ex tensive.
In very young subjects we occasionally see examples of diffuse inflammation which has engaged the periosteum of the femur or tibia, and the epiphysis of one or both of these bones, the inflammation extending to the knee-joint. These cases are usually rapid in their course, and too frequently terminate fatally, the ordi nary symptoms of diffuse inflammation being exhibited in their progress. In the post-mortem investigations of these cases we find that the periosteum is extensively separated from the bones by purulent matter ; that the epiphyses, detached from the shafts of their respective bones, are loose in the interior of the joint; and that the synovial membrane is dis tended by matter. In the serous and mu cous membranes of the chest also we generally find evidences of acute inflammation having existed. The origin of these violent attacks is sometimes referred to a fall or other accidental injury, sometimes to a cold which commenced with a rigour. We have sometimes known this severe form of disease to succeed imme diately to attacks of small-pox, and also of scarlatina. Dr. M'Dowel, in the third and fourth volumes of the Dublin Journal, has de scribed this disease under the heads Periostitis and Synovitis ; and the museum of the Rich mond hospital contains many specimens of these unhappy results of diffuse inflammation.
Cases of diffuse inflammation are not the only ones in which we have seen matter, formed beneath the periosteum of the tibia, passing the epiphysis and getting into the cavity of the knee-joint ; we have known in stances of such occurrences in cases of acute necrosis of the tibia, in which the disease in its commencement had been exclusively confined to the one bone. Mr. Smyly, one of the sur geons to the Meath Hospital, presented to the museum of the College of Surgeons in Dublin, a specimen, the result of an acute necrosis of the tibia. The following is the history of this case, which he kindly communicated to the writer. James Jarman, wt. 9, was admitted into the Meath Hospital the 5th October, 1837. Sixteen days previously he had suffered a very severe contusion on the front of the left tibia by the accidental falling of an iron bar; there was, however, no breach of the skin, and the boy was able to walk about as usual for two days, when acute inflammation attacked the contused part, and daily increased for a fort night. On the 4th of October he applied for relief at the dispensary. At this time a large and tense swelling extended from above the knee to the instep ; a fluctuation was evident the whole way down the front of the leg. An incision was made into this swelling, which gave exit to a considerable quantity of thin discoloured pus, and the tibia was found quite denuded of periosteum. Great relief followed the opening of the abscess, but on the 10th of October there was much tumefaction observa ble at each side of the patella, and redness, as if the joint were in a state of suppuration. The boy suffered much from irritative fever and occasional diarrhoea : his pulse became very frequent, and his tongue red and dry. The ope ration of amputation at the lower third of the thigh was now the only resource, and it was accordingly performed.