CHAPTER I.

OF THE PERIOSTEUM AND BONES.

Section I. OF THE PERIOSTEUM.

[=Notice=: degree of vascularity; thickness; density; detached or adhered; effusions beneath; serum or pus; ulcerative destruction of; condition of bone beneath, etc.]

=Inflammation= of the periosteum occurs in the vicinity of chronic ulcers; as essential to the reproduction of bone after fractures; in consequence of syphilis or its mercurial treatment; in rheumatism; and as a manifestation of a scrofulous cachexia.

In incipient inflammation, the membrane has a reddish tinge, a humid, succulent appearance, and there is more or less of a serous effusion, causing a slight separation from the bone. As the inflammation advances, the connection between the membrane and the bone becomes more lax, and the effusion assumes a purulent character.

Syphilitic inflammation of the periosteum is apt to appear in detached spots, causing swelling, induration, the formation of new osseous matter and necrosis. The periosteum of the skull, sternum and tibia are most frequently attacked.

A malignant disease of the periosteum, the consequence of long-continued or repeated attacks of inflammation, is described by Stanley. It occurs on the bones of the hips, and gives rise to the growth of a fungous excrescence upon the membrane. “This is sometimes soft and flocculent on its surface, with a firm, grayish, gelatinous base; at others it consists throughout of a firm, gelatinous substance.”

Section II. OF THE BONES.

[=Notice=: 1. _Surface of bone_—smooth or rough, firm and hard or soft; periosteum present or destroyed; caries; necrosis; tumors, etc. 2. _Whole bone_—weight and size increased, or diminished? bent or fractured? 3. _Appearance on section_—density of different portions; condition of cancellated portion; destroyed, or softened; abscesses; caries; necrosis; tumors, etc. 4. _Medulla_—density, color, vascularity, morbid growths.]

=Inflammation and Abscess.= Acute inflammation rarely takes place except in connection with mechanical injury.

Inflammatory processes in bone, give rise for the most part, to an increase of medullary tissue, and to softening of the osseous structure. Haversian canals and medullary spaces increase in size, and ultimately become confluent by the gradual absorption of the surrounding osseous lamellæ. The results of progressive inflammation are congestion, exudation, suppuration, caries and necrosis. An enlargement of the affected portion is invariably met with.

In case the exudation be absorbed, or the inflammatory process be arrested, the parts may return to their normal condition, or the bone retains a permanently disorganized condition, which may present either an increased condensation and induration, as in gouty bone, or an abnormal rarefaction of the bone, as in the bones of rickety individuals.

The same state of rarefaction, or _osteoporosis_, according to Lobstein, is occasionally met with in advanced life, as an effect of mal-nutrition.

_Suppuration_, with the formation of _abscess_, may be diffused or circumscribed. In circumscribed abscess, we find a cavity generally in or near the epiphyses, lined with a vascular membrane, and thickening of the adjoining periosteum, and of the surrounding cellular tissue.

=Caries.= Caries, a process of molecular disintegration, may occur in all bones, and in every part of their structure, though it generally affects the cancellous tissue. The carious bone is porous and fragile, of a gray, brown, or blackish color, partly broken down in softened masses, and partly hollowed out into cells, which contain a reddish-brown and oily fluid. Small portions of dead bone lie detached in the carious cavity. The periosteal and medullary membranes, and the bone around the carious portion, will be found extremely vascular, and in many cases, compact masses of osseous tissue are deposited around the carious cavity.

Caries of bone occurs as a result of inflammation, and corresponds to ulceration of the soft tissues. It frequently results from chronic suppurative arthritis, when, from destruction of the articular cartilages, the disease attacks the cancellated structure of the extremity of the bone.

=Necrosis.= The death of a portion of osseous tissue, or necrosis, although frequently accompanied with caries, is entirely distinct from it. It attacks principally the compact tissue, and is met with, therefore, most frequently in the shafts of long bones. The necrosed portion is of a dirty, yellowish-white color, and has a dull, opaque look; after exposure to the air, it gradually becomes of a green, deep brown, or black tint. Its boundaries are usually distinct, but sometimes are so imperceptibly lost in the healthy tissue, that it becomes difficult in the dead body to determine its exact limits.

Necrosis results from causes which interfere with the nutrition of bone, as from suppurative periostitis, traumatic destruction of the periosteum, or osteitis. Ulcerative destruction of the surrounding soft parts, or the diminished vitality attending certain general diseases, as typhus, etc., may also result in necrosis.

The death of a portion of bone is followed by inflammation at the dividing line, which finally results in the separation of the dead portion or sequestrum. This change is soon followed by the production of new bone, in which process the periosteum and medulla may take part.

=Rachitis or Rickets=, is essentially a disease of mal-nutrition, most frequently affecting children between the first and third years, although it does also occasionally occur later. The lower extremities are the first to show the effects of the disease, by a curvature commonly referred to too early attempts at walking. A contortion of the bones of the pelvis, of the spine, the thorax, the upper extremities, and malformations of the skull, may follow in the course of the disease.

The bone on analysis, shows a decided diminution in the quantity of phosphate of lime, and a uniform increase of fatty matter; fluoride of calcium always present in healthy born, is also wanting.

The joints are usually swollen, and the epiphyses of the bones enlarged by the exudation of a reddish serum into the enlarged cancelli and canals, the osseous corpuscles, at the same time, showing a deficiency or entire absence of earthy matter. The periosteum is pulpy and thickened, and more than usually adherent to the bone.

If a reparative process have been set up, the deformity may have been greatly diminished, or even entirely removed; or a new deposit of bone taken place, so as to afford a useful limb during life. “This supplementary ossification is found, on vertical section of a long bone, chiefly on the concave side, so that this part of the shaft may present double and treble the thickness of the opposite side. The structure, at the same time, is very dense, and of ivory texture.”

In flat bones, as in those of the skull—which is commonly unduly large in rickety subjects—there is a uniform thickening. In some cases the thickening affects the capacity of the foramina.

In a peculiar form of disease of the cranium described by Elsasser, the bone is atrophied, soft and porous; numerous openings are found along the lambdoidal suture, and in the body of the bone, with the exception of the occipital protuberance. The perforations are filled up only by the dura mater and pericranium, which are adherent to one another. This disease is commonly met with between the third and sixth months of infant life.

=Mollities Ossium, or Osteomalacia=, is regarded by some as a form of atrophy, by others as identical with rachitis, except that it attacks adults instead of children, and by others as an essentially distinct osseous disease.

It is of rare occurrence, and consists in perverted nutrition of the skeleton, whereby the earthy phosphates are eliminated from the system by the kidneys, while a deposit of fat takes place in the cartilaginous matrix.

As the bones of the trunk are especially liable to be attacked, the individual affected becomes reduced in size by the collapse of the vertebral column.

It attacks females more frequently than males, and the former chiefly after they have commenced child-bearing.

The disease presents two varieties—the _waxy_, in which the bones, especially those of the pelvis, present a dirty, dark-yellow color, and remain greasy after drying; and the _fragile_, where the bones are of a snowy whiteness, and of a light, transparent, open texture, and so fragile that they give way under the mere pressure of the finger.

Under the microscope, we find the corpuscles and their canaliculi empty and transparent, and only faintly visible, and the Haversian canals unnaturally enlarged.

Morbid Growths.

=Enchondromatous Tumors=, are usually found in connection with some of the short bones, more particularly those of the fingers and toes, though the ribs, vertebræ, sternum, tibia and femur are sometimes attacked.

They may originate on the surface of the bone, or within the cancellous tissue. In the former case, they exhibit a lobulated arrangement, and are surrounded by a fibrous sheath; in the latter, the bone gradually expands with the development of the tumor. The rapidity and extent of their growth vary. In their microscopic characters, the enchondroma resembles normal cartilage.

The central variety presents a semi-elastic feel, and, on section, the knife passes through a thin, crackling shell of bone, and then exhibits a white, cartilaginous mass, which is occasionally found to contain some small cells; while in some tumors there is an interlacement of fibrous tissue, in which cartilage is imbedded.

The superficial variety is microscopically and chemically identical with the central form, but has no osseous shell. It is met with chiefly in the pelvis, on the cranium, and on the ribs.

There may be a partial ossification.

The disease is chiefly met with in early life.

=Osseous Growths=, consisting of true bone, are divided into _exostoses_ and _osteophytes_. The surface of the former is smooth; their outline generally a segment of a circle or of an ellipse; their cause: an idiosyncracy of the individual, not referable to any definite constitutional taint. Of the latter, the surface is rough; they do not form any well defined _local_, circumscribed tumor; are referable to rheumatic or gouty inflammation, to syphilis or other causes.

Exostoses are of two kinds: the one, hard and compact; the other, softer and more spongy. The _hard_ or _ivory exostosis_ is extremely dense, and whiter than the bone from which it springs, but possesses a true bony structure. It generally grows from flat bones, and is of small size. It has been known to necrose and to slough away from the parts on which it has been situated.

_Spongy exostoses_ often attain a considerable size, and are very commonly multiple. They differ from the compact variety in being composed of cancelli, containing medullary matter, and surrounded by a shell of bone. They spring from the cancellous, or compact tissue of the bone, and their surface is continuous with that of the latter. In some cases the cavity of the exostosis communicates directly, or is continuous, with the medullary cavity of the bone. Their most common seats are the tibia, fibula and humerus.

The _osteophyte_ chiefly affects the more vascular portions of bones, as their articular ends, their rough lines, or, in the skull, the sutural cartilages; being generally the product of an inflammatory process in the superficial part of the bone, and in the periosteum.

=Fibrous Growths= always develop in the cancellous structure. All the long bones and many of the flat bones are liable to this disease. They present more or less elasticity, are of a gray and opaque appearance, and yield gelatin on boiling. They may attain an enormous size.

=Cystic Tumors= are of rare occurrence, and are generally met with in adults.

They may be unilocular, usually filled with a solid mass of a fibro-cellular or fibro-cartilaginous character; or multilocular, with thin and serous, sero-sanguinolent, viscid or dark-colored contents, often associated with central, fibrous growths.

_Hydatid cysts_ have been met with. According to Stanley, both the acephalocyst and the cysticercus cellulosæ have been found, but more frequently the former.

=Tubercles= are occasionally present in bone, as the yellow, opaque tubercles, deposited chiefly in the spongy bones and the cancellous portions of long bones. They may soften or become cretified.

=Vascular Tumors= are of not very frequent occurrence. They are met with most commonly in the cancellous articular ends of the long bones; although they have also been found in the pelvic bones, the bones of the skull, and in the ribs.

In the most frequent class of cases, a new tissue is developed in the osseous structure, and the tumor partakes of an encephaloid character. A creamy, curdy or brain-like, soft, and very vascular mass, is formed as the essential constituent. This will be found to present every shade of transition, from a purely vascular tissue, of an erectile character, to true encephaloid cancer.

In a second, more rare form of disease, there is developed in the bone a _vascular_, _erectile_ growth, closely resembling capillary nævus in its structure, composed of an infinity of blood-vessels, interlacing in every possible way, so as to form a soft, reddish-yellow tumor.

In a third form, a hollow cavity is formed in the bone, scooped out of the cancellous structure and filled with blood, partly liquid and partly coagulated, and having arterial branches freely opening into it. According to the stage of the disease, the blood is found in cells, intersected by fibres, or laminæ and fibres, the remains of the original osseous structure; or in a more advanced stage, in a single cavity. The shell of bone surrounding the cavity is very thin and expanded, being usually absorbed at one point, where it often becomes at last perforated. This last class constitutes _true aneurism_ of bone.

_Cephalohæmatoma_, met with in infancy on the cranial bones, as a result of pressure during parturition, is an effusion of blood between the pericranium and the bone, commonly occurring on one of the parietal bones, most frequently on the right side. Rare cases of internal cephalohæmatoma have been recorded in which the effusion took place between the dura mater and the bones.

=Cancer= of bone most frequently occurs in the head of the tibia and the lower end of the thigh bone, occasionally in the humerus and in the jaws, more especially about the antrum.

The encephaloid variety is the most frequent. It is of two distinct forms: in the one, the morbid growth is central, springing from the medullary canal; in the other, it is peripheral, being attached to the compact osseous substance.

In the _central_ form, it is usually situated at or about the articular ends, but always affects the whole of the bone by infiltration.

In the _peripheral_, the more common form of cancer of the bone, the osseous tissue is not so completely invaded; for although the disease may be located upon, or in intimate contact with the outer layers of the bone, which are incorporated in it, it does not extend into the cancellous tissue or the medullary canal. In this form, the muscles attached to the affected portion of bone will often be found extensively infiltrated with cancer cells.

Encephaloid of bone is harder and more fibrous looking than the same affection elsewhere. The cancer cell also is not so well marked, and may indeed be absent altogether. Occasionally some colloid, and more rarely melanotic matter, is intermixed, but scirrhus is never found in bone.

Of the Medulla.

“It is yet to be determined in how far the medulla is liable to be primarily affected. It varies in consistency according to the vigor of the individual; while in dropsical and phthisical cases we find it thin and serous, or yellow in icterus, or very scanty in ivory condensation of a bone. It exhibits greater firmness, and a richer pink hue, in habits tending to an inflammatory character. The real seat of inflammation in bone is the membrane that lines its cavities. It is, therefore, fair to infer that, in all diseases dependent upon the state of the vascular system, whether of an ordinary or of a malignant character, the medulla is affected coincidently with, if not previously to, the bony tissue itself.”

_Morbid growths_, of various kinds, may be found within the medulla.

The Cysticercus cellulosæ, and Echinococcus, are said to have been detected within the medulla and periosteum.