Bone

Bone (a word common in various forms to Teutonic languages, in many of which it is confined to the shank of the leg, as in the German Bein), the hard tissue constituting the framework of the animal skeleton. For anatomy see Skeleton and Connective Tissues.

Bone Diseases and Injuries.—The more specific diseases affecting the bones of the human body are treated under separate headings; in this article inflammation of bone and fractures are dealt with.

Ostitis (ὀστέον, bone), or inflammation of bone, may be acute or chronic. Acute ostitis is one of the most serious diseases which can be met with in young people. It is due to the cultivation of virulent germs in the delicate growing Ostitis. tissue of the bone and in the marrow. Another name for it is septic osteomyelitis, which has the advantage of expressing the cause as well as the exact seat (μυελός, marrow) of the inflammation. The name of the micro-organism causing the inflammation is Staphylococcus pyogenes aureus, which means that the germs collect in clusters like grapes, that they are of the virulent pus-producing kind, and that they have a yellow tinge. As a rule, the germs find their way to the bone by the blood-stream, which they have entered through the membrane lining the mouth or gullet, or some other part of the alimentary canal. In the pre-antiseptic days they often entered the sawn bone during the amputation of a limb, and were not infrequently the cause of blood-poisoning and death. When the individual is well and strong, and there has been no hurt, strain or accident to lower the power of resistance of the bone, the staphylococci may circulate harmlessly in the blood, until they are gradually eaten up by the white corpuscles; but if a bone has been injured it offers a likely and attractive focus to the wandering germs.

The disease is infective. That is to say, the micro-organisms having begun to germinate in the damaged bone find their way by the blood-stream into other tissues, and developing after their kind, are apt to cause blood-poisoning. Should a surgeon prick his finger whilst operating on a case of septic osteomyelitis his blood also might be poisoned, and he would run the risk of losing his finger, his hand, or even his life. The starting-point of the disease is the delicate growing tissue recently deposited between the main part of the shaft of the bone (diaphysis) and the cartilaginous end. And it often happens that the earliest complaint of pain is just above or below the knee; just above the ankle, the elbow or the wrist. If the surgeon is prompt in operating he may find the disease limited to that spot. In the case of infants, the germs are very apt to make their way into the neighbouring joint, giving rise to the very serious disease known as acute arthritis of infants.

Probably the first sign of there being anything amiss with the limb will be a complaint of aches or pains near a joint; and these pains are apt to be miscalled rheumatic. Perhaps they occur during convalescence from scarlet or typhoid fever, or after exposure to injury, or to wet or cold, or after unusual fatigue. The part becomes swollen, hot, red and excessively tender; the tenderness, however, is not in the skin but in the bone, and in the engorged membrane around it, the periosteum. The temperature may run up to 104°, and may be associated with convulsions or shiverings. The patient’s nights are disturbed, and very likely he has violent delirium. If the case is allowed to drift on, abscess forms, and death may ensue from septic pneumonia, or pericarditis, or from some other form of blood-poisoning.

As soon as the disease is recognized an incision should be made down to the bone, and the affected area should be scraped out, and disinfected with a solution of corrosive sublimate. A considerable area of the bone may be found stripped bare by sub-periosteal abscess, and necrosis is likely to ensue. Perhaps the shaft of the bone will have to be opened up in the chief part of its length in order that it may be cleared of germs and pus. The surgeon is more apt to err on the side of doing too little in these serious cases than too much. It may be that the whole of that piece of bone (diaphysis) which lies between the joint-ends is found loose in a large abscess cavity, and in some cases immediate amputation of the limb may be found necessary in order to save life; in other cases, amputation may be called for later because of long-continued suppuration and grave constitutional disturbance. Several bones may be affected at the same time, and large pieces of them may be killed outright (multiple necrosis) by inflammatory engorgement and devastating abscess.

Septic ostitis may be confounded with erysipelas and rheumatism, but the central thickening and tenderness should suffice to distinguish it.

Chronic ostitis and periostitis denote long-continued and increased vascular supply. This may be due to injury, syphilis or rheumatism. The disease is found chiefly in the shafts of the bones. There is a dull pain in the bone, which is worse at night, and the inflamed piece of bone is thickened and tender. The lump thus formed is called a hard node, and its outline shows clearly by X-rays. The affected limb should be rested and kept elevated. Leeches and fomentations may ease the pain, and iodide of potassium is the most useful medicine.

Chronic inflammation of tuberculous origin affects the soft, cancellated tissue of such bones as the vertebrae, and the bones of the hands and feet, as well as the spongy ends of the long bones. In tuberculous ostitis the presence of the bacilli in the spongy tissue causes an escape of colourless corpuscles from the blood, which, collecting around the bacilli, form a small greyish white heap, a tubercle. These tubercles may be present in large numbers at the expense of the living tissue, and a rarefying ostitis is thus produced. Later the tubercles break down and form tuberculous abscesses, which slowly, and almost painlessly, find escape upon the surface. They should not be allowed to open spontaneously, however, as the wounds are then likely to become infected with pus-producing germs, and fuel being added to the fire, as it were, destruction advances with increased rapidity. The treatment for these tuberculous foci is to place the limb or the part at absolute rest upon a splint, to give plenty of fresh air to the patient, and to prescribe cod-liver oil and iron. And when it is seen that in spite of the adoption of these measures the tuberculous abscess is advancing towards the surface, the surgeon should cut down upon the part, scrape out the foci, and disinfect with some strong antiseptic lotion. Consideration should also be given to the treatment by injection of tuberculin.

Caries (rottenness, decay) is the name given to tuberculous disease of bone when the tubercles are running together and are breaking down the cancellous tissue. In short, caries generally means tuberculous ostitis, though syphilitic ulceration of bone has also received the same name.

Fractures.—A bone may be broken at the part where it is struck (fracture from direct violence), or it may break in consequence of a strain applied to it (fracture from indirect violence), or the fracture may be due to muscular action Fracture. as when a violent cough causes a rib to break. In the first case the fracture is generally transverse and in the second more or less oblique. The fully developed bone is broken fairly across; the soft bones of young people may simply be bent—green stick or willow fracture. Fractures are either simple or compound. A simple fracture is analogous to the subcutaneous laceration in the soft parts, and a compound one to an open wound in the soft parts. The wound of the soft parts in the compound fracture may be due either to the force which caused the fracture, as in the case of a cart-wheel going over a limb, first wounding the soft parts and then fracturing the bone, or to the sharp point of the fractured bone coming out through the skin. In either case there is a communication between the external air and injured bone, and the probability arises of the germs of suppuration finding their way to the seat of fracture. This greatly increases the risks of the case, for septic inflammation and suppuration may lead to delayed union, to death of large pieces of the bone (necrosis), and to osteomyelitis and to blood-poisoning. In the treatment of a fracture, every care should be taken to prevent any sharp fragment coming near the skin. Careless handling has often been the means of a simple fracture being converted into a compound one.

In most cases of fracture crepitus can be made out; this is the feeling elicited when two rough osseous surfaces are rubbed together. When a bone is merely bent there is, of course, no crepitus. It is also absent in fractures in which the broken extremities are driven into one another (impacted fracture). In order to get firm bony union it is necessary to secure accurate apposition of the fragments. Putting the broken ends together is termed “setting the fracture,” and the needful amount of rest is obtained by the use of splints. As a rule, it is also advisable to fix with the splint the joint above or below the fracture. In cases in which a splintering of the bone into a joint has taken place, more especially in those cases in which tendons have been injured, there may be a good deal of effusion into the joint and the tendon sheaths, and this may be organized into fibrous tissue leading to permanent stiffness. This is particularly apt to occur in old people. Care must be taken in such instances by gentle exercises, and by passive movement during the process of cure, to keep the joint and tendons free. To take a common example,—in fracture close to the wrist joint, it is necessary to arrange the splint so that the patient can move his fingers and thumb, and the splint must be taken off every day, in order that the wrist and fingers may be gently bent, straightened and exercised.

The treatment of fractures has undergone considerable improvement of late years. Simple fractures are not kept so long at rest in splints, but are constantly “taken down” in order that massage and movements of the limb may be resorted to. This, of course, is done with the utmost gentleness, and with the result that swelling, pain and other evidences of the serious injury quickly disappear, whilst a more rapid and complete recovery is ensured. Stiff hands and feet after fracture are much less frequently met with. By the aid of the X-rays it is now easy for the surgeon to assure himself that fractured surfaces have been well adjusted and are in close apposition. But if they are not in a satisfactory position, and it be found impracticable to assure their close adjustment by ordinary methods, the surgeon now, without undue loss of time, cuts down upon the broken ends and fixes them together by a strong wire suture, which remains permanently in the tissues. If the fracture be associated with an open wound of the part (compound fracture), and the broken ends are found incapable of easy adjustment, immediate wiring together of the fragments is now considered to be a necessary part of the primary treatment. The French surgeon, Just Lucas-Championnière, has done more than any one else to show the advantage of discreet movements, of massage and of exercises in the treatment of fractures.

Special Fracture in Young People.—The long bones of children and growing persons consist of a shaft with cartilaginous ends in which bone is developed. As the result of injury, the end of the bone may become detached, a variety of fracture known as diastasis. Such a fracture—however well treated—may be followed by arrest of growth of the bone or by stiffness of the neighbouring joint.

Delayed union means that consolidation is taking place very slowly, if at all. This may be due to local or constitutional causes, but provided the bones are in good position, nothing further than patience, with massage, and with due attention to general health-measures, is necessary.

An ununited fracture is one in which after many weeks or months no attempt has been made by nature to consolidate the parts. This may be due to the ends not having been brought close enough together; to the seat of fracture having been constantly disturbed; to muscle or tendon being interposed between the broken ends, or to the existence of some constitutional defect in the patient. Except in the last-named condition, the treatment consists in cutting down to the broken ends; freshening them up by sawing off a thin slice, and by adjusting and fixing them by a wire or screw. Ununited fracture of the leg-bones in children is a most unsatisfactory and rebellious condition to deal with.

There is still a difference of opinion as to the best way of treating a recent fracture of the patella (knee-cap). Many surgeons are still content to follow the old plan of fixing the limb on a back-splint, or in plaster of Paris splints, and awaiting the result. It is beyond question that a large percentage of these cases recover with a perfectly useful limb—especially if the fibrous bond of union between the pieces of the broken knee-cap is adequately protected against being stretched by bending the leg at too early a date. But in some cases the fragments have been eventually found wide apart, the patient being left with an enfeebled limb. Still, at any rate, this line of treatment was unassociated with risk. But after Lister showed (1883) that with due care and cleanliness the knee-joint could be opened, and the fragments of the broken patella secured in close apposition by a stout wire suture, the treatment of the injury underwent a remarkable change. The great advantage of Lister’s treatment was that the fragments, being fixed close together by the wire stitch, became solidly united by bone, and the joint became as sound as it was before. Some surgeons, however, objected to the operation—in spite of the excellence of the results obtainable by it—because of the undoubted risk which it entailed of the joint becoming invaded by septic micro-organisms. As a sort of compromise, Professor A.E.J. Barker introduced the method, which he deemed to be less hazardous, of holding the fragments close together by means of a strong silver wire passed round them vertically by a large needle without actually laying open the joint. But experience has shown that in the hands of careful and skilful surgeons Lister’s operation of openly wiring the fragments gives a perfect result with a comparatively small risk. Other surgeons secure the fragments in close contact for bony union by passing a silk or metal suture around them circumferentially. Many years ago Lister remarked that the careful selection of one’s patients is an antiseptic measure—by which he meant that if a surgeon intended to get the most perfect results for his operative work, he must carefully consider whether any individual patient is physically adapted for the performance upon him of any particular operation. This aphorism implies that not every patient with a broken knee-cap is suited for the opening of his knee-joint, or even for the subcutaneous adjustment of the broken fragments. An operative procedure which is admirably suited for one patient might result in disaster when adopted for another, and it is an important part of the surgeon’s business to know what to advise in each individual case.

(E. O.*)

Industrial Applications of Bones.—By the increasing inventiveness of man, the industrial utilization of animal bone has been so developed that not one of the constituents fails to reappear in commerce. Composed of mineral matter—phosphates, &c.—fat and gelatinous substances, the phosphates are used as artificial manures, the fat is worked up by the soap-maker and chandler, and the gelatinous matter forms the basis of the gelatin and glue of commerce; while by the dry distillation of bones from which the gelatin has been but partially removed, there are obtained a carbonaceous residue—animal charcoal—and a tarry distillate, from which “bone oil” and bone pitch are obtained. To these by-products there must be added the direct uses of bone—for making buttons, knife-handles, &c.—when an estimate is desired of the commercial importance of these components of the animal frame.

While most of the world’s supply of bones goes to the glue and gelatin works, the leg and thigh bones, termed “marrows” and “knuckles,” are used for the manufacture of bone articles. The treatment which they receive is very different from that practised in the glue-works. The ends are removed by a saw, and the bones are steeped in a 1% brine solution for three to four days, in order to separate the fibrous matter. The bones are now heated with water, and allowed to simmer for about six hours. This removes a part of the fat and gelatinous matter; the former rises as a scum, the latter passes into solution, and the bones remain sufficiently firm to be worked up by the lathe, &c. The fat is skimmed off, and, after bleaching, reappears as a component of fine soaps, or, if unbleached, the oil is expressed and is used as an adulterant of other oils, while the stearine or solid matter goes to the candle-maker; the gelatinous water is used (after filtration) for making size for cardboard boxes; while the bones are scrubbed, dried, and then transferred to the bone-worker.

The glue-worker first removes the fat, which is supplied to the soap and candle trades; the bones are now treated for glue (q.v.); and the residue is worked up for manures, &c. These residues are ground to a fine or coarse meal, and supplied either directly as a fertilizer or treated with sulphuric acid to form the more soluble superphosphates, which are more readily assimilated by growing plants. In some places, especially South America, the residues are burned in a retort to a white ash, the “bone-ash” of commerce, which contains some 70-80% of tricalcium phosphate, and is much used as a manure, and in the manufacture of high-grade superphosphates. In the gelatin industry (see Gelatin) the mineral matter has to be recovered from its solution in hydrochloric acid. To effect this, the liquors are freed from suspended matter by filtration, and then run into vats where they are mixed with milk of lime, or some similar neutralizer. The slightly soluble bicalcium phosphate, CaHPO4, is first precipitated, which, with more lime, gives ordinary tricalcium phosphate, Ca3(PO4)2. The contents of the vats are filter-pressed, and the cakes dried on plates supported on racks in heated chambers. This product is a very valuable manure, and is also used in the manufacture of phosphorus.

Instead of extracting all the gelatinous matter from degreased bones, the practice of extracting about one half and carbonizing the residue is frequently adopted. The bones are heated in horizontal cast-iron retorts, holding about 5 cwt., and the operation occupies about twelve to thirteen hours. The residue in the retorts is removed while still red-hot to air-tight vessels in which it is allowed to cool. It is then passed through grinding mills, and is subsequently riddled by revolving cylindrical sieves. The yield is from 55 to 60% of the bones carbonized, and the product contains about 10% of carbon and about 75% of calcium phosphate, the remainder being various inorganic salts and moisture (6-7%). Animal charcoal has a deep black colour, and is much used as a filtering and clarifying material. The vapours evolved during carbonization are condensed in vertical air condensers. The liquid separates into two layers: the upper tarry layer is floated off and redistilled; the distillate is termed “bone oil,”1 and mainly consists of many fatty amines and pyridine derivatives, characterized by a most disgusting odour; the residue is “bone pitch,” and finds application in the manufacture of black varnishes and like compositions. The lower layer is ammoniacal liquor; it is transferred to stills, distilled with steam, and the ammonia received in sulphuric acid; the ammonium sulphate, which separates, is removed, drained and dried, and is principally used as a manure. Both during the carbonization of the bones and the distillation of the tar inflammable gases are evolved; these are generally used, after purification, for motive or illuminating purposes.

(C. E.*)

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1 Bone oil, also known as Dippel’s oil, was originally produced by the distillation of stags’ horns; it is of interest in the history of chemistry, since from it were isolated in 1846 by T. Anderson pyridine and some of its homologues.

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