Alexis Thomson and Alexander Miles - Manual of Surgery

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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 spaces and
Haversian canals 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 canal for a varying distance, and also
extends to the periosteum by way of the enlarged Haversian canals. The
pus accumulates under the periosteum and lifts it up from the bone. The
extent of spread in the medullary canal 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 space.

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 constitutes 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 assumes 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
associated 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 constitutional symptoms, which are due to the
associated 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 succumb 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 oedema 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 attitude of the limb; it is nearly always
associated 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 attitude 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 passed involuntarily. The temperature is remittent and
irregular, the pulse small and rapid, and the urine may contain blood
and albumen. 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 pronounced 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 space 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
canal 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
associated 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 accumulation 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 passing a probe down one of the
sinuses it usually passes 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 canal 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.

[Illustration: FIG. 118.--Shaft of Femur after Acute Osteomyelitis. The
shaft has undergone extensive necrosis, and a shell 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).

The _extrusion of a sequestrum_ may occur, provided there is a cloaca
large enough to allow of its escape, but the surgeon has usually to
interfere by performing the operation of sequestrectomy. Displacement or
partial extrusion of the dead bone may cause complications, as when a
sequestrum derived from the trigone of the femur perforates the
popliteal artery or the cavity of the knee-joint, or a sequestrum of the
pelvis perforates the wall of the urinary bladder.

The extent to which bone which has been lost is reproduced varies in
different parts of the skeleton: while the long bones, the scapula, the
mandible, and other bones which are developed in cartilage are almost
completely re-formed, bones which are entirely developed in membrane,
such as the flat bones of the skull and the maxilla, are not reproduced.

[Illustration: FIG. 119.--Femur and Tibia showing results of Acute
Osteomyelitis affecting Trigone of Femur; sequestrum partly surrounded
by new case; backward displacement of lower epiphysis and implication of
knee-joint.]

It may be instructive to describe _the X-ray appearances of a long bone
that has passed through an attack of acute osteomyelitis_ severe enough
to have caused necrosis of part of the diaphysis. The shadow of the dead
bone is seen in the position of the original shaft which it represents;
it is of the same shape and density as the original shaft, while its
margins present an irregular contour from the erosion concerned in its
separation. The sequestrum is separated from the living bone by a clear
zone which corresponds to the layer of granulations lining the cavity in
which it lies. This clear zone separating the shadow of the dead bone
from that of the living bone by which it is surrounded is conclusive
evidence of a sequestrum. The medullary canal in the vicinity of the
sequestrum being obliterated, is represented by a shadow of varying
density, continuous with that of the surrounding bone. The shadow of the
new case or involucrum with its wavy contour is also in evidence, with
its openings or cloacae, and is mainly responsible for the increase in
the diameter of the bone.

The skiagram may also show separation and displacement of the adjacent
epiphysis and destruction of the articular surfaces or dislocation of
the joint.

_Sequelae of Acute Suppurative Osteomyelitis._--The commonest sequel is
the presence of a sequestrum with one or more discharging sinuses; owing
to the abundant formation of scar tissue these sinuses have rigid edges
which are usually depressed and adherent to the bone.

_The Recognition and Removal of Sequestra._--So long as there is dead
bone there will be suppuration from the granulations lining the cavity
in which it lies, and a discharge of pus from the sinuses, so that the
mere persistence of discharge after an attack of osteomyelitis, is
presumptive evidence of the occurrence of necrosis. Where there are one
or more sinuses, the passage of a probe which strikes bare bone affords
corroboration of the view that the bone has perished. When the dead bone
has been separated from the living, the X-rays yield the most exact
information.

The traditional practice is to wait until the dead bone is entirely
separated before undertaking an operation for its removal, from fear, on
the one hand, of leaving portions behind which may keep up the
discharge, and, on the other, of removing more bone than is necessary.
This practice need not be adhered to, as by operating at an earlier
stage healing is greatly hastened. If it is decided to wait for
separation of the dead bone, drainage should be improved, and the
infective element combated by the induction of hyperaemia.

_The operation_ for the removal of the dead bone (_sequestrectomy_)
consists in opening up the periosteum and the new case sufficiently to
allow of the removal of all the dead bone, including the most minute
sequestra. The limb having been rendered bloodless, existing sinuses are
enlarged, but if these are inconveniently situated--for example, in the
centre of the popliteal space in necrosis of the femoral trigone--it is
better to make a fresh wound down to the bone on that aspect of the
limb which affords best access, and which entails the least injury of
the soft parts. The periosteum, which is thick and easily separable, is
raised from the new case with an elevator, and with the chisel or gouge
enough of the new bone is taken away to allow of the removal of the
sequestrum. Care must be taken not to leave behind any fragment of dead
bone, as this will interfere with healing, and may determine a relapse
of suppuration.

The dead bone having been removed, the lining granulations are scraped
away with a spoon, and the cavity is disinfected.

There are different ways of dealing with a _bone cavity_. It may be
packed with gauze (impregnated with "bipp" or with iodoform), which is
changed at intervals until healing takes place from the bottom; it may
be filled with a flap of bone and periosteum raised from the vicinity,
or with bone grafts; or the wall of bone on one side of the cavity may
be chiselled through at its base, so that it can be brought into contact
with the opposite wall. The method of filling bone cavities devised by
Mosetig-Moorhof, consists in disinfecting and drying the cavity by a
current of hot air, and filling it with a mixture of powdered iodoform
(60 parts) and oil of sesame and spermaceti (each 40 parts), which is
fluid at a temperature of 112 F.; the soft parts are then brought
together without drainage. As the cavity fills up with new bone the
iodoform is gradually absorbed. Iodoform gives a dark shadow with the
X-rays, so that the process of its absorption can be followed in
skiagrams taken at intervals.

These procedures may be carried out at the same time as the sequestrum
is removed, or after an interval. In all of them, asepsis is essential
for success.

The _deformities_ resulting from osteomyelitis are more marked the
earlier in life the disease occurs. Even under favourable conditions,
and with the continuous effort at reconstruction of the bone by Nature's
method, the return to normal is often far from perfect, and there
usually remains a variable amount of hyperostosis and sclerosis and
sometimes curving of the bone. Under less favourable conditions, the
late results of osteomyelitis may be more serious. _Shortening_ is not
uncommon from interference with growth at the ossifying junction.
_Exaggerated growth_ in the length of a bone is rare, and has been
observed chiefly in the bones of the leg. Where there are two parallel
bones--as in the leg, for example--the growth of the diseased bone may
be impaired, and the other continuing its normal growth becomes
disproportionately long; less frequently the growth of the diseased
bone is exaggerated, and it becomes the longer of the two. In either
case, the longer bone becomes curved. An _obliquity_ of the bone may
result when one half of the epiphysial cartilage is destroyed and the
other half continues to form bone, giving rise to such deformities as
knock-knee and club-hand.

Deformity may also result from vicious union of a pathological fracture,
permanent displacement of an epiphysis, contracture, ankylosis, or
dislocation of the adjacent joint.

#Relapsing Osteomyelitis.#--As the term indicates, the various forms of
relapsing osteomyelitis date back to an antecedent attack, and their
occurrence depends on the capacity of staphylococci to lie latent in the
marrow.

Relapse may take place within a few months of the original attack, or
not for many years. Cases are sometimes met with in which relapses recur
at regular intervals for several years, the tendency, however, being for
the attacks to become milder as the virulence of the organisms becomes
more and more attenuated.

_Clinical Features._--Osteomyelitis in a patient over twenty-five is
nearly always of the relapsing variety. In some cases the bone becomes
enlarged, with pain and tenderness on pressure; in others there are the
usual phenomena which attend suppuration, but the pus is slow in coming
to the surface, and the constitutional symptoms are slight. The pus may
escape by new channels, or one of the old sinuses may re-open.
Radiograms usually furnish useful information as to the condition of the
bone, both as it is altered by the original attack and by the changes
that attend the relapse of the infective process.

_Treatment._--In cases of thickening of the bone with persistent and
severe pain, if relief is not afforded by the repeated application of
blisters, the thickened periosteum should be incised, and the bone
opened up with the chisel or trephine. In cases attended with
suppuration, the swelling is incised and drained, and if there is a
sequestrum, it must be removed.

#Circumscribed Abscess of Bone--"Brodie's Abscess."#--The most important
form of relapsing osteomyelitis is the circumscribed abscess of bone
first described by Benjamin Brodie. It is usually met with in young
adults, but we have met with it in patients over fifty. Several years
may intervene between the original attack of osteomyelitis and the onset
of symptoms of abscess.

_Morbid Anatomy._[7]--The abscess is nearly always situated in the
central axis of the bone in the region of the ossifying junction,
although cases are occasionally met with in which it lies nearer the
middle of the shaft. In exceptional cases there is more than one abscess
(Fig. 120). The tibia is the bone most commonly affected, but the lower
end of the femur, or either end of the humerus, may be the seat of the
abscess. In the quiescent stage the lesion is represented by a small
cavity in the bone, filled with clear serum, and lined by a fibrous
membrane which is engaged in forming bone. Around the cavity the bone is
sclerosed, and the medullary canal is obliterated. When the infection
becomes active, the contents of the cavity are transformed into a
greenish-yellow pus from which the staphylococcus can be isolated, and
the cavity is lined by a thin film of granulation tissue which erodes
the surrounding bone and so causes the abscess to increase in size. If
the erosion proceeds uniformly, the cavity is spherical or oval; if it
is more active at some points than others, diverticula or tunnels are
formed, and one of these may finally erupt through the shell of the bone
or into an adjacent joint. Small irregular sequestra are occasionally
found within the abscess cavity. In long-standing cases it is common to
find extensive obliteration of the medullary canal, and a considerable
increase in the girth of the bone.