Manual of Surgery Volume I Part 47

The term _caries_ is employed to indicate any diseased process a.s.sociated with crumbling away of the trabecular framework of a bone. It may be considered as the equivalent of ulceration or molecular destruction in the soft parts. The carious process is preceded by the formation of granulation tissue in the marrow or periosteum, which eats away and replaces the bone in contact with it. The subsequent degeneration and death of the granulation tissue under the necrotic influence of bacterial toxins results in disintegration and crumbling away of the trabecular framework of the portion of bone affected.

Clinically, carious bone yields a soft grating sensation under the pressure of the probe. The macerated bone presents a rough, eroded surface.

The term _dry caries_ (_caries sicca_) is applied to that variety which is unattended with suppuration.

_Necrosis_ is the term applied to the death of a tangible portion of bone, and the dead portion when separated is called a _sequestrum_. The term _exfoliation_ is sometimes employed to indicate the separation or throwing off of a superficial sequestrum. The edges and deep surface of the sequestrum present a serrated or worm-eaten appearance due to the process of erosion by which the dead bone has been separated from the living.

BACTERIAL DISEASES

The most important diseases in this group are the pyogenic, the tuberculous, and the syphilitic.

PYOGENIC DISEASES OF BONE.--These diseases result from infection with pyogenic organisms, and two varieties or types are recognised according to whether the organisms concerned reach their seat of action by way of the blood-stream, or through an infection of the soft parts in contact with the bone.

INFECTIONS THROUGH THE BLOOD-STREAM

#Diseases caused by the Staphylococcus Aureus.#--As the majority of pyogenic diseases are due to infection with the staphylococcus aureus, these will be described first.

#Acute osteomyelitis# is a suppurative process beginning in the marrow and tending to spread to the periosteum. The disease is common in children, but is rare after the skeleton has attained maturity. Boys are affected more often than girls, in the proportion of three to one, probably because they are more liable to exposure, to injury, and to violent exertion.

_Etiology._--Staphylococci gain access to the blood-stream in various ways, it may be through the skin or through a mucous surface.

Such conditions as, for example, a blow, some extra exertion such as a long walk, or exposure to cold, as in wading, may act as localising factors.

The long bones are chiefly affected, and the commonest sites are: either end of the tibia and the lower end of the femur; the other bones of the skeleton are affected in rare instances.

_Pathology._--The disease commences and is most intense in the marrow of the ossifying junction at one end of the diaphysis; it may commence at both ends simultaneously--_bipolar osteomyelitis_; or, commencing at one end, may spread to the other.

The changes observed are those of intense engorgement of the marrow, going on to greenish-yellow purulent infiltration. Where the process is most advanced--that is, at the ossifying junction--there are evidences of absorption of the framework of the bone; the marrow s.p.a.ces and Haversian ca.n.a.ls undergo enlargement and become filled with greenish-yellow pus. This rarefaction of the spongy bone is the earliest change seen with the X-rays.

The process may remain localised to the ossifying junction, but usually spreads along the medullary ca.n.a.l for a varying distance, and also extends to the periosteum by way of the enlarged Haversian ca.n.a.ls. The pus acc.u.mulates under the periosteum and lifts it up from the bone. The extent of spread in the medullary ca.n.a.l and beneath the periosteum is in close correspondence. The periosteum of the diaphysis is easily separated--hence the facility with which the pus spreads along the shaft; but in the region of the ossifying junction it is raised with difficulty because of its intimate connection with the epiphysial cartilage. Less frequently there is more than one collection of pus under the periosteum, each being derived from a focus of suppuration in the subjacent marrow. The pus perforates the periosteum, and makes its way to the surface by the easiest anatomical route, and discharges externally, forming one or more sinuses through which fresh infection may take place. The infection may spread to the adjacent joint, either directly through the epiphysis and articular cartilage, or along the deep layer of the periosteum and its continuation--the capsular ligament. When the epiphysis is intra-articular, as, for example, in the head of the femur, the pus when it reaches the surface of the bone necessarily erupts directly into the joint.

While the occurrence of purely periosteal suppuration is regarded as possible, we are of opinion that the embolic form of staphylococcal osteomyelitis always originates in the marrow.

The portion of the diaphysis which has sustained the action of the concentrated toxins has its vitality further impaired as a result of the stripping of the periosteum and thrombosis of the blood vessels of the marrow, so that _necrosis_ of bone is one of the most striking results of the disease, and as this takes place rapidly, that is, in a day or two, the term _acute necrosis_, formerly applied to the disease, was amply justified.

When there is marked rarefaction of the bone at the ossifying junction, the epiphysis is liable to be separated--_epiphysiolysis_. The separation usually takes place through the young bone of the ossifying junction, and the surfaces of the diaphysis and epiphysis are opposed to each other by irregular eroded surfaces bathed in pus. The separated epiphysis may be kept in place by the periosteum, but when this has been detached by the formation of pus beneath it, the epiphysis is liable to be displaced by muscular action or by some movement of the limb, or it is the diaphysis that is displaced, for example, the lower end of the diaphysis of the femur may be projected into the popliteal s.p.a.ce.

The epiphysial cartilage usually continues its bone-forming functions, but when it has been seriously damaged or displaced, the further growth of the bone in length may be interfered with. Sometimes the separated and displaced epiphysis dies and const.i.tutes a sequestrum.

The adjacent joint may become filled at an early stage with a serous effusion, which may be sterile. When the cocci gain access to the joint, the lesion a.s.sumes the characters of a purulent arthritis, which, from its frequency during the earlier years of life, has been called _the acute arthritis of infants_.

Separation of an epiphysis nearly always results in infection and destruction of the adjacent joint.

Osteomyelitis is rare in the bones of the carpus and tarsus, and the a.s.sociated joints are usually infected from the outset. In flat bones, such as the skull, the scapula, or the ilium, suppuration usually occurs on both aspects of the bone as well as in the marrow.

_Clinical Features._--The const.i.tutional symptoms, which are due to the a.s.sociated toxaemia, vary considerably in different cases. In mild cases they may be so slight as to escape recognition. In exceptionally severe cases the patient may succ.u.mb before there are obvious signs of the localisation of the staphylococci in the bone marrow. In average cases the temperature rises rapidly with a rigor and runs an irregular course with morning remissions, there is marked general illness accompanied by headache, vomiting, and sometimes delirium.

The local manifestations are pain and tenderness in relation to one of the long bones; the pain may be so severe as to prevent sleep and to cause the child to cry out. Tenderness on pressure over the bone is the most valuable diagnostic sign. At a later stage there is an ill-defined swelling in the region of the ossifying junction, with dema of the overlying skin and dilatation of the superficial veins.

The swelling appears earlier and is more definite in superficial bones such as the tibia, than in those more deeply placed such as the upper end of the femur. It may be less evident to the eye than to the fingers, and is best appreciated by gently stroking the bone from the middle of its shaft towards the end. The maximum thickening and tenderness usually correspond to the junction of the diaphysis with the epiphysis, and the swelling tails off gradually along the shaft. As time goes on there is redness of the skin, especially over a superficial bone, such as the tibia, the swelling becomes softer, and gives evidence of fluctuation.

This stage may be reached at the end of twenty-four hours, or not for some days.

Suppuration spreads towards the surface, until, some days later, the skin sloughs and pus escapes, after which the fever usually remits and the pain and other symptoms are relieved. The pus may contain blood and droplets of fat derived from the marrow, and in some cases minute particles of bone are present also. The presence of fat and bony particles in the pus confirms the medullary origin of the suppuration.

If an incision is made, the periosteum is found to be raised from the bone; the extent of the bare bone will be found to correspond fairly accurately with the extent of the lesion in the marrow.

_Local Complications._--The adjacent joint may exhibit symptoms which vary from those of a simple effusion to those of a purulent _arthritis_.

The joint symptoms may count for little in the clinical picture, or, as in the case of the hip, may so predominate as to overshadow those of the bone lesion from which they originated.

_Separation and displacement of the epiphysis_ usually reveals itself by an alteration in the att.i.tude of the limb; it is nearly always a.s.sociated with suppuration in the adjacent joint.

When _pathological fracture_ of the shaft occurs, as it may do, from some muscular effort or strain, it is attended with the usual signs of fracture.

_Dislocation_ of the adjacent joint has been chiefly observed at the hip; it may result from effusion into the joint and stretching of the ligaments, or may be the sequel of a purulent arthritis; the signs of dislocation are not so obvious as might be expected, but it is attended with an alteration in the att.i.tude of the limb, and the displacement of the head of the bone is readily shown in a skiagram.

_General Complications._--In some cases a _multiplicity of lesions_ in the bones and joints imparts to the disease the features of pyaemia. The occurrence of endocarditis, as indicated by alterations in the heart sounds and the development of murmurs, may cause widespread infective embolism, and metastatic suppurations in the kidneys, heart-wall, and lungs, as well as in other bones and joints than those primarily affected. The secondary suppurations are liable to be overlooked unless sought for, as they are rarely attended with much pain.

In these multiple forms of osteomyelitis the toxaemic symptoms predominate; the patient is dull and listless, or he may be restless and talkative, or actually delirious. The tongue is dry and coated, the lips and teeth are covered with sordes, the motions are loose and offensive, and may be pa.s.sed involuntarily. The temperature is remittent and irregular, the pulse small and rapid, and the urine may contain blood and alb.u.men. Sometimes the skin shows erythematous and purpuric rashes, and the patient may cry out as in meningitis. The post-mortem appearances are those of pyaemia.

_Differential Diagnosis._--Acute osteomyelitis is to be diagnosed from infections of the soft parts, such as erysipelas and cellulitis, and, in the case of the tibia, from erythema nodosum. Tenderness localised to the ossifying junction is the most valuable diagnostic sign of osteomyelitis.

When there is early and p.r.o.nounced general intoxication, there is likely to be confusion with other acute febrile illnesses, such as scarlet fever. In all febrile conditions in children and adolescents, the ossifying junctions of the long bones should be examined for areas of pain and tenderness.

Osteomyelitis has many features in common with acute articular rheumatism, and some authorities believe them to be different forms of the same disease (Kocher). In acute rheumatism, however, the joint symptoms predominate, there is an absence of suppuration, and the pains and temperature yield to salicylates.

The _prognosis_ varies with the type of the disease, with its location--the vertebrae, skull, pelvis, and lower jaw being specially unfavourable--with the multiplicity of the lesions, and with the development of endocarditis and internal metastases.

_Treatment._--This is carried out on the same lines as in other pyogenic infections.

In the earliest stages of the disease, the induction of hyperaemia is indicated, and should be employed until the diagnosis is definitely established, and in the meantime preparations for operation should be made. An incision is made down to and through the periosteum, and whether pus is found or not, the bone should be opened in the vicinity of the ossifying junction by means of a drill, gouge, or trephine. If pus is found, the opening in the bone is extended along the shaft as far as the periosteum has been separated, and the infected marrow is removed with the spoon. The cavity is then lightly packed with rubber dam, or, as recommended by Bier, the skin edges are brought together by sutures which are loosely tied to afford sufficient s.p.a.ce between them for the exit of discharge, and the hyperaemic treatment is continued.

When there is widespread suppuration in the marrow, and the shaft is extensively bared of periosteum and appears likely to die, it may be resected straight away or after an interval of a day or two. Early resection of the shaft is also indicated if the opening of the medullary ca.n.a.l is not followed by relief of symptoms. In the leg and forearm, the unaffected bone maintains the length and contour of the limb; in the case of the femur and humerus, extension with weight and pulley along with some form of moulded gutter splint is employed with a similar object.

Amputation of the limb is reserved for grave cases, in which life is endangered by toxaemia, which is attributed to the primary lesion. It may be called for later if the limb is likely to be useless, as, for example, when the whole shaft of the bone is dead without the formation of a new case, when the epiphyses are separated and displaced, and the joints are disorganised.

Flat bones, such as the skull or ilium, must be trephined and the pus cleared out from both aspects of the bone. In the vertebrae, operative interference is usually restricted to opening and draining the a.s.sociated abscess.

#Nature's Effort at Repair.#--_In cases which are left to nature_, and in which necrosis of bone has occurred, those portions of the periosteum and marrow which have retained their vitality resume their osteogenetic functions, often to an exaggerated degree. Where the periosteum has been lifted up by an acc.u.mulation of pus, or is in contact with bone that is dead, it proceeds to form new bone with great activity, so that the dead shaft becomes surrounded by a sheath or case of new bone, known as the _involucrum_ (Fig. 118). Where the periosteum has been perforated by pus making its way to the surface, there are defects or holes in the involucrum, called _cloacae_. As these correspond more or less in position to the sinuses in the skin, in pa.s.sing a probe down one of the sinuses it usually pa.s.ses through a cloaca and strikes the dead bone lying in the interior. If the periosteum has been extensively destroyed, new bone may only be formed in patches, or not at all. The dead bone is separated from the living by the agency of granulation tissue with its usual complements of phagocytes and osteoclasts, so that the sequestrum presents along its margins and on its deep surface a pitted, grooved, and worm-eaten appearance, except on the periosteal aspect, which is unaltered. Ultimately the dead bone becomes loose and lies in a cavity a little larger than itself; the wall of the cavity is formed by the new case, lined with granulation tissue. The separation of the sequestrum takes place more rapidly in the spongy bone of the ossifying junction than in the compact bone of the shaft.

When foci of suppuration have been scattered up and down the medullary cavity, and the bone has died in patches, several sequestra may be included by the new case; each portion of dead bone is slowly separated, and comes to lie in a cavity lined by granulations.

Even at a distance from the actual necrosis there is formation of new bone by the marrow; the medullary ca.n.a.l is often obliterated, and the bone becomes heavier and denser--sclerosis; and the new bone which is deposited on the original shaft results in an increase in the girth of the bone--hyperostosis.

[Ill.u.s.tration: FIG. 118.--Shaft of Femur after Acute Osteomyelitis. The shaft has undergone extensive necrosis, and a sh.e.l.l of new bone has been formed by the periosteum.]

_Pathological fracture_ of the shaft may occur at the site of necrosis, when the new case is incapable of resisting the strain put upon it, and is most frequently met with in the shaft of the femur. Short of fracture, there may be bending or curving of the new case, and this results in deformity and shortening of the limb (Fig. 119).