CHAPTER IV.
SUPPURATION IN BONE.
Surpuration in bone is in some cases of small extent, and the matter is contained in a single round or oval cavity hollowed out of the substanee of the bone. But in other instances the matter is diffused more or less cx- tensively through the cancellous texture or medullary tube of the bone. Thus the absecss in bone is conve- nicutly distinguished into the eircumseribed and diffused.
The cireumscribed absecss is mostly situated near to, or within, the articular ends of long bones; but I have seen itin the middle of their shafts. The cavity in the bone is usually lined by a very vasenlar membrane, and around it the bone is hardened, also, in some instances, enlarged by the expansion of its texture, The periosteum and ad- jacent cellular tissuc covering this part of the bone are generally thiekened. In some cases a narrow passage has formed in the osscous wall of the abscess, through whieh the matter has escaped from the interior of the bone. In this way the matter has passed from the abseess within the articular end of a bone into the adjacent joint; and I have known seyeral mstanees of destruction of the knee- joint consequent on the cseape of matter into it: in some cases, from the articular end of the femur, and in others, �
