Читать книгу Elements of Surgery - Robert Liston - Страница 25

Death of bone, or Necrosis, is an effect of violent inflammation, particularly of the medullary web, or external injury; a termination of inflammatory action in bone corresponding to sphacelation in the softer tissues. It has been observed, that the bones are not extensively supplied with bloodvessels, and that their natural powers are inferior to those of the softer parts; and from this circumstance the frequency of necrosis can be readily accounted for. The short bones and the heads of the long bones, are more vascular than the flattened bones and the shafts of the long ones. Hence necrosis most frequently occurs in the latter. Necrosis, fortunately, seldom occurs in the heads of the long bones, or penetrates the separation betwixt the cancelli of the shaft and the epiphysis. Bits of dead bone in the articular ends, however, very often lead to disease in the joint. There are in my private collection a few specimens of necrosis, in which matter found its way into the neighbouring joint, leading to disease of the tissues composing it, and rendering amputation necessary for the preservation of the patient’s existence. External injury may produce this disease by causing a violent increase of action, or it may be so severe as at once to deprive part of the bone of its vitality. Destruction of the periosteum, and of the vessels which enter the surface of the bone, frequently gives rise to superficial necrosis or exfoliation. Such a result, however, does not always follow; for we not unfrequently find, when the periosteum has been forcibly torn off, to a considerable extent, by external injury, that the part still retains its vitality. When, however, the bone has been at the same time contused, it is extremely probable that external necrosis may occur. Again, when the periosteum has been removed in the most careful manner possible, exfoliation occasionally takes place. If the exposed bone remain of a brownish hue, it will generally retain its vigour; if, on the other hand, the colour is white, it will most probably be cast off. Necrosis may come on at various periods of life, but is most commonly met with in young subjects, in whom the inflammatory action is allowed to make progress before it is noticed or attended to. It may affect the external or the internal part of a bone, or nearly its whole thickness. The whole of a bone seldom or ever dies in consequence of increased action, and it is not often that the entire thickness of any part of it is found to be necrosed. If the entire thickness dies to a great extent, there is no reproduction; the epiphyses approximate, and the limb, if there is only a single bone, must be lost. A large portion of a bone, or numerous small irregular portions, may die; but still a part of the original shaft remains, and by its vessels reproduction is accomplished. The articulating extremity is very rarely destroyed by this disease. Many writers have talked of death of a bone throughout its whole extent, and, in fact, the term necrosis was originally adopted on this supposition.

The progress of necrosis is, as has been said, similar to that of sphacelation. The affected bone gradually changes its colour, and loses its sensibility; a line of demarcation is formed, and ultimately the dead portion is completely detached from the living. Previous to its separation, the surrounding parts, the portions of bone which are not doomed to perish, have commenced forming new osseous matter, which is secreted in nodules, and from continued deposition soon becomes consolidated. The commencement of the process is well seen in the following sketches from specimens in my collection. The disease, as represented in the two first cuts, was of the most acute kind, and a great part of the shaft of the tibia had perished. This is seen at various points through the sort of cortical deposit of new bone. The new bone, in its turn, secretes a texture similar to itself, whereby the deposit becomes more and more extended, and not unfrequently affords an almost complete encasement to the dead portion, or sequestrum, as represented in the cut on the right-hand side of the page. In general bone dies irregularly, so that the sequestrum presents an uneven surface, and its margins are rough and serrated by numerous sharp projections, as seen in the one taken from the tibia, and represented here. From the appearance of the dead bone, it was imagined that after its separation, portions of it were removed by absorption; and this opinion was strengthened by the thin exfoliations of the external lamina being found perforated at several points by minute apertures,—worm-eaten, as it was called. These cases of death of inner or medullary shell are irregularly separated, like any other slough; the remaining living outer shell is enlarged by inflammatory action and deposit. But a dead portion of bone, detached from the surrounding parts, is in every respect an extraneous body, and is not, and cannot be, acted on by the absorbents, any more than a piece of metal, wood, or stone. Some have gone so far as to affirm that portions of foreign bodies, ligatures, &c., are absorbed; but this opinion is altogether too absurd to require any contradiction; the knots of ligatures, like portions of glass, or other foreign substance, become surrounded with a dense cyst, and often remain in the body for a long time; so do portions of dead bone separated by the process here described. A series of experiments were made by Mr. Gulliver, in order to put this question at rest, many of which I witnessed and assisted at, and several I also repeated. Setons of bone were inserted and worn for a long time; thin plates of bone were confined on suppurating surfaces; pieces of bone were inserted in the medullary canal of various animals, and kept there for months, and in one instance for more than a year. These foreign bodies were weighed with the greatest care and accuracy before and after they were so exposed to the absorbents, and were found unaltered in any respect. A paper, detailing these experiments, is published in the Medico-Chir. Transactions.

The separation of the dead part from the living is accomplished with greater or less ease, according to the bone which is affected, the state of the constitution, and the general health; in the bones of the superior extremity, this, as well as every other action, proceeds more rapidly than in those of the inferior. It occurs in consequence of absorption of the living part of the bone, which is in close proximity to the dead. The sequestrum, if large, is not pushed off, as some have supposed, by granulations, deposited on the living margin of the bone. A small portion of the inner shell, when completely detached, may sometimes be observed to be extruded from a cloaca by granulations from the living bone. During its progress, matter forms, makes its way to the surface, and is discharged through minute, and often numerous apertures, which afterwards become fistulous. The soft parts are thickened and indurated, and the integuments are red, and sometimes of a livid colour.

Formation of matter upon the bone is occasionally the cause of necrosis, the periosteum being destroyed or separated from its connections by the pressure or insinuation of the pus. I have seen several instances in which it followed neglected erysipelas of the lower extremity.

The matter is in general thick and laudable; at first it is secreted profusely, but afterwards in smaller quantity. The external openings, or papillæ, through which it is discharged, are found to lead to cloacæ, or apertures in the new and living bone, which encase the dead, and through these the dead portions can be discovered by the probe; and it will thus be ascertained whether the sequestrum is fixed or detached: when loose, it can sometimes be moved upward and downward in the cavity. When the shaft of a bone is much affected, the whole limb is enlarged, by the inflammation having extended to a considerable distance above and below the portion about to become necrosed. The unshapely appearance of the limb continues until the sequestra are discharged; for by their presence incited action is still continued, and subsides only after their removal. Some time before any portion of bone has become dead, or begun to be separated, great effusion of new bone has, in general, occurred; thus a preparation has been made for the strengthening of the limb, which, after a considerable portion of the bone has been detached, would otherwise be incapable of supporting the weight of the body. The unnatural bulk of the limb is afterwards much diminished, for the new bone gradually becomes consolidated, and smooth on the surface by the action of the absorbents. Nature seems to construct her substitute after the model of the original, and in some instances but very little change can afterwards be observed in the limb.

In external necrosis, or death of the outer lamella, reparation is chiefly made by the subjacent parts; and this species of necrosis occurs most frequently in the flat bones. In necrosis involving a greater thickness of the bone, the new matter is also furnished by the subjacent parts, which, however, are materially assisted in the process by the living bone, which forms the margins of the void caused by the absorbent process for the detachment of the dead portion. The bony matter is deposited with great activity, and frequently columns of the new deposit cross over the sequestrum, binding it firmly down, and rendering it almost immovable, although it may be completely detached from the living parts.

It has already been stated, that those vessels which ramify within the substance of the periosteum have no share in the reproduction of bone, but plastic matter is effused by the ramifications extending from the membrane to the bone: this effusion becomes organised, and greatly assists in forming the substitute.

It has been formerly remarked, that a limited, and, on after examination, an apparently trifling necrosis of the cancellated structure, may produce the most violent local symptoms; the painful feelings, the discharge, and the thickening of the bone, continue, as long as the cancellated sequestrum remains; severe symptomatic fever is induced, endangering the life of the patient, and often rendering removal of the limb absolutely necessary.

Occasionally abscesses form at a considerable distance from the necrosed part, and terminate in sinuses, which communicate with the diseased bone, and are consequently long and tortuous, so that examination by the probe is rendered difficult. When necrosis is extensive, there is a risk of fracture occurring, if motion of the limb be permitted before a sufficient quantity of matter has been effused, before nature has had sufficient time for the consolidation of her substitute, and consequently before the new bone has come to resemble the old in thickness and cohesion.

Violent inflammatory fever attends the incited action of the vessels of the bone and periosteum which precedes necrosis. But after the abscesses have given way the painful symptoms subside, and the health seldom suffers to any great extent, the system becoming gradually accustomed, as it were, to the new condition of the parts. Hectic supervenes only when the disease is very extensive, and joints become involved. Frequently fresh collections of matter form as each piece of bone approaches the surface. When the effusion of new bone has extended to the neighbourhood of a joint, its motion may be very much impeded, and, from the limb being kept in a state of rest for the cure of the necrosis, anchylosis may even occur.

Treatment.—The means of preventing inflammatory action from running high and ending in death of bone have been already alluded to—abstraction of blood, rest, purgatives, and antimonials. When necrosis has occurred, no interference with the bone is allowable, unless the sequestrum is quite loose, or unless the patient’s health is suffering severely under the discharge and irritation. When the sequestrum can be readily moved about, or when, projecting through the external opening, it can be laid hold of by the fingers or forceps, attempts must be made to remove it. The surgeon ought not, however, to allow it to approach the surface, and project externally, for the natural discharge of the sequestrum is a much more tedious process than the removal of it by art, and by the irritation produced during its spontaneous ejection the inflammatory action is continued, and may prove alarming. Long before it has appeared externally, it must have been completely separated from the living parts, so as to admit of ready extraction by the proper means. When it has been ascertained that the sequestrum is separated, it ought to be laid hold of by forceps, and moved freely upward and downward, so that any slight attachments by which it is connected to the neighbouring parts may be destroyed, whether these be minute filaments which still in some degree retain their vitality, or small portions of newly deposited bone, which are so situated as to prevent the free movement of the sequestrum. In general, no impediment of this nature exists, and the dead bone is easily removed. Before extraction can be accomplished, it is generally necessary to enlarge freely the external opening, in all cases where the dead portion of bone is of considerable size. If, on thus exposing the parts, the sequestrum be found detached, but still firmly bound down by the substitute bone, deposited over it either in one continuous sheet, or in irregular columns, this must be divided by a trephine, a small saw, or cutting pliers, before the sequestrum can be extracted. When a dead portion of bone, of considerable length, is exposed at its centre, whilst its extremities are entangled by the old or substitute bone, the division of the exposed part of sequestrum, by means of the cutting pliers, will often be sufficient for its removal, the cut ends being seized by the forceps, and one half removed after the other; thus the perforation or removal of any portion of the substitute will be rendered unnecessary. The instruments, and especially those for extraction, ought to be very powerful, and suited to the purpose; for in the employment of inefficient means there is much folly and cruelty. Incisions into a necrosed limb are attended with profuse hemorrhage from the enlarged and excited vessels; and in some cases it is with difficulty arrested, in consequence of retraction of the cut ends of the vessels not taking place within the condensed and indurated parts. Pressure, and an elevated position of the part, will generally be found to answer. When necrosis has been extensive, the limb must be carefully supported by the application of splints and bandage, till the process of reparation be completed, in order to prevent fracture of the recently formed substitute. This proceeding is seldom, however, necessary.

The treatment may be summed up in a very few words. Prevent the necrosis, if possible; open abscesses whenever they appear; encourage the patient to move the neighbouring joints; support the strength; remove sequestra when loose, but do not interfere till they are ascertained to be so; give the limb proper support and rest, when a large sequestrum is formed. When fracture has taken place, when the health has been undermined, or when neighbouring joints have become diseased, amputate, in order to save the life, if it be impossible to save the limb.

It is almost superfluous to remark, that leeching and blistering are worse than useless after necrosis has occurred, however useful they may be in preventing it; and that the adoption of measures to promote the dissolution and absorption of the sequestra are glaringly absurd.

Necrosis, after amputation, was formerly frequent; but in the present improved state of this operation it is so rare as scarcely to demand separate consideration.

Such specimens as here depicted are common enough in the collections of those who have practised the old round-about operation; in fact, it is only by this painful and tedious interference of nature that a tolerable stump is formed in many of these cases. Death of a small portion will sometimes, though very rarely, follow even a very well performed amputation, if through any mischance the recovery is slow, and wasting discharge takes place with emaciation. It happens sometimes, as when secondary hemorrhage (that is to say, bleeding after the fourth day) has taken place, that the flaps are separated by the coagula, and it may be impossible to bring the parts together and give them due support; then the muscles, wasted and shrunk, may leave the bone a little, but the exfoliation is but very trifling.

The inner shell of bone, as may be seen in the above sketch, perishes more extensively than the outer; and this arises probably from inflammation of the medullary membrane, in consequence of exposure, or, perhaps, from its being sometimes injured by the operator or assistants seizing the bone rudely to steady the stump, in order to facilitate the ligature of the vessels. In experiments on animals, the disturbance and injury of the medullary membrane is followed by internal necrosis, thickening of the outer living shell, and effusion betwixt the periosteum and bone. New bone is also furnished from the medullary canal, as is also shown in the sketch.