INFLAMMATION OF BONE.
It has been seen that bone has blood-vessels passing through its substance in great numbers, and that it is coated without and within by men, b es --periosten in and end ostenm —w h ich also are richly supplied with vessels. Bone is, therefore, liable to the changes that occur in intlamniation. It is also easily understood that the disease may attack (I) the substance of the bone itself, or (2) the periostenm, or (3) the endosteum and the cavity containing the mar row, which it lines. In the first case the in flammation is called ostitis, in the second periostitis, in the third osteomyelitis.
Inflammation of Bone itself (Ostitis). Course.—(I) Increased quantity of blood and the enlargement of the blood spaces, which are the earlier occurrences of inflammation, cause the bone first of all to become less dense, more porous, and therefore lighter, softer, and more fragile. (2) But succeeding this is a stage of thickening, when material which has passed through the walls of the inflamed blood-vessels becomes organized to form new tissue. In this tissue bone salts become deposited, and thus quantities of new bone are formed which fill up the spaces of the healthy bone and render it more hard, and dense, and thick. Should the disease not be arrested at this point other consequences may follow. (3) The continued inflammation may cause suppuration and the formation of an abscess. The matter may be collected at one place in the bone ; but, in cases of of very bad constitution, the matter may extend all through the bone. (4) Ulcera tion may occur, in which the bone breaks down or may be said to melt down into unhealthy matter, which works its way to the surface and bursts. It may burst into a joint. As the ulceration continues there is a constant dis charge through the opening that has been formed. This ulceration in bone is called caries. It is not likely to result from inflam mation of bone in persons of good habit of body, but is liable to occur in persons, and specially young persons, whose constitution is tainted with scrofula. It occurs oftenest in the spongy part of the bone, and particularly in the heads of the long bones, and in short bones like those of the wrist, or foot, or the vertebrae. (5) The
bone may die, not in minute particles, as in caries, but in pieces, either in a thin slice from the surface or a complete portion of the whole thickness of the shaft may die. This mode of termination of inflammation is called necrosis, and the dead piece is called a sequestrum. When part of the shaft of a long bone has died in this way it is not uncommon for the peri osteum (from which, as already mentioned, the growth in the circumference of the bone pro. coeds) to produce a layer of new bone, so that, the dead portion becomes encased within 4 shell of new material.
This disease may be acute or chronic. It is in the chronic cases that very great thickening, caries, or necrosis will result. It often extends over years with intervalsof rest between attacks. It occurs oftenest in the young, and in the bones of the head and of the thigh or leg (femur or tibia). It is usually attributed to cold, but the chronic forms may be due to constitutional disease like scrofula, or tubercle or syphilis. Symptoms.—The first sign is violent, deep seated pain, worse at night. There is high fever, ushered in by shivering. In a few days there is swelling of the leg in the neighbour hood of the diseased bone, the skin becoming red and boggy to the feeling. The health suffers rapidly and severely, the patient often sinking under the violence of the attack. If an abscess forms in the bone there is often severe fixed pain at one particular spot which nothing relieves. When caries or necrosis has occurred there will generally be one or more openings through the soft parts which refuse to close. In necrosis this open channel, sinus, as it is called, will lead down to the dead bone, and a probe being passed in the right direction will touch it and give a rough, grating, and metallic feeling, sometimes the piece being felt to be loose in the cavity. In caries, thin, ill-smelling matter will issue from the opening, the edges of which arc red and pouting, and a probe gives the sensation of softness and grittiness, the bone breaking down under the touch.