Osteomyelitis

Physiopathology

Congestive phase

At the time of a Septicaemia or a Bactériémie, the germ reaches the bone by blood way. On the level of the métaphyse, blood flow slows down what supports the fixing and the development of the germs.

Abscess under périosté

The diffusion of the infection is done through the channels of Havers and Volkmann of cortical until reaching the périoste. This last thickens, raises and delimits an abscess under périosté.

Stage necroses osseous

It occurs in the absence of an early treatment of the infection and leads to a chronic osteomyelitis. The interruption of osseous vascularization as well centromédullaire as under périosté one involves necroses osseous with formation of a dead bone avasculaire, free in the abscess, named osseous sequestration.

clinical Picture

Osteomyelitis frequently occurs during the second childhood with an average age 6 years. It is exceptional in period néonatale. It sits preferentially on the level of the most fertile métaphyses, “near to the knee”, “far from the elbow”. In 30 to 40% of the cases, one notes occurred of a minor traumatism in the previous days the appearance of the infection. In the typical case, it is about a boy (Sex Ratio 3/1) who complains about circumferential pains métaphysaires at the end of a long bone. The pain has a brutal, pseudo-fracturaire beginning and is accompanied by a functional impotence of the member reached. The soft mobilization of the adjacent articulation is possible. The infectious syndrome is marked with a fever higher than 38°, a deterioration of the general state, shivers and sweats. In phase of beginning, the local signs are poor. More tardily, one can observe an edema and a localized ignition. Usually, one does not find adenopathy. Other demonstrations must make especially seek an osteomyelitis in a feverish context:

a state of agitation or prostration;
a pseudoparalysy of a member at the infant or the newborn;
of the convulsions;
a boitery.

In front of any fever in a child, it is necessary to palpate all the fertile métaphyses and to mobilize all the articulations more especially as the pains sit “near to the knee and far from the elbow”. The remainder of the clinical examination will seek a main door is:

cutaneous;
urinary;
ORL and pulmonary;
méningée.

Complementary examinations

Biological assessment

NFS shows a hyperleucocytosis with polynuclear neutrophiles. The absence of rise should not make challenge the diagnosis.
CRP (C. Réactv. Protéïn.) (NR < 10 mg/l): it increases precociously as of the 6th hour. It can be normal in 20% of the cases.
Orosomucoïde (NR < 1 g/l) is seldom normal.
VS (NR < 20 per 1st hour): it increases more tardily than of the same CRP its standardization is much slower.

Assessment with bacteriological aiming

It is to be realized before any treatment. The Staphylocoque gilded is the germ responsible in the majority for the cases. The Streptocoque of group has is the second germ by order of frequency. In 3 year old lower part, there is prevalence of hæmophilus influenzæ of the type G.

Hémocultures are to be realized even in the absence of fever but especially in the event of feverish peaks of shivers. They are positive in 40 to 60% of the cases. A puncture métaphysaire will be carried out under general anesthesia and control of the amplifier of brightness. It isolates a germ in 90 to 100% from the cases.

Other taking away

urinary cyto-bacteriological examination (ECBU);
taking away ORL;
taking away of a cutaneous lesion;
céphalo-rachidian liquid (LCR);
electrophoresis of hemoglobin in the search of a drépanocytose (prone blacks or Maghrebians).

Radiographic assessment

The Radiography S standard of face, profile supplemented by comparative stereotypes and of 3/4 in case of doubt about a lesion. At the stage of the beginning, one seeks a blur of the adjacent soft parts to the métaphyse. With the phase of state, one seeks an affixing of fine osseous plates to cortical the métaphysaire corresponding to the périostée reaction. More tardily appear:

of the gaps métaphysaires;
of the irregularities of the cortical ones;
of the osseous sequestrations (osseous fragment of free and irregular dense aspect).

The radiographic aspect of certain malignant tumors, such as the sarcome of Ewing, can simulate an osteomyelitis. The diagnosis must be evoked in the event of evolution torpid or atypical and confirmed by a surgical biopsy.

The osseous scintiscanning with technetium 99 m

It shows a hyperfixation but does not allow to make the difference between infection, tumors or another inflammatory pathology. She will be asked in case of diagnostic doubt or to seek an attack multifocale. The use of Gallium 67 would be more specific infection because the isotope is fixed on the leucocytes.

Echography

It allows the tracking and the guided puncture of the périosté abscess.

The I.R.M.

It gives early information before standard radiography but its realization in the child requires sometimes a general anesthesia. It shows a hyposignal in T1 and a hypersignal in T2. After Gadolinium injection, one notes a raising of inflammatory fabrics. On the other hand, on the level of the abscess, one does not observe raising or only in periphery.

The scanner

Especially it makes it possible to especially study the osseous extension in the chronic forms (heterogeneous aspect) and to detect the presence of a sequestration, fragment of dead bone which acts like a foreign body and supports the persistence of the dents: it is an essential component of the surgical indication in the persistent suppurations. it also makes it possible to study the vertebral and sacro-iliaques localizations.

Clinical forms

Subacute osteomyelitis

It is distinguished from hematogen acute osteomyelitis by its insidious beginning, a rough symptomatology with few local signs. In the typical cases, the evolution is benign. The biological assessment is not very disturbed. The radiographic aspect is a well circumscribed gap épiphysaire but which sometimes reached the cortical one. The treatment remains discussed. Classically, one recommends the administration of an antibiotic with antistaphylococcic aiming. Certain reported observations evolved to the cure without treatment.

Chronic osteomyelitis

It is the evolution of an acute osteomyelitis in the absence of an early and adapted treatment. The bacteria in question are the same ones as in acute osteomyelitis. In the event of chronic suppuration, one can observe a superinfection by germs such as the pseudomonas. Brodie and Garre described chronic ostémyélites from the start. They were called primary chronic osteomyelitides. Other forms of chronic osteomyelitides from the start were described; it is the case of the chronic forms hyperostosantes.

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