Diagnosis of osteomyelitis

Currently, the diagnosis of osteomyelitis, clarification of the localization and extent of damage, as well as determining the effectiveness of treatment is based on laboratory, bacteriological, morphological and radiation methods of research, which can be divided into priority and additional ones.

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Laboratory diagnostics of osteomyelitis

Laboratory tests are useful for establishing the inflammatory process and its severity. Numerous studies have shown that the content of leukocytes in the blood does not serve as a sensitive indicator. However, other markers of inflammation, such as ESR and C-reactive protein, although not specific, but because of their sensitivity can be useful in patients with suspected this pathology. The number of leukocytes, ESR and concentration of C-reactive protein should be checked on admission and during treatment in all patients. Other laboratory tests can be used to monitor liver and kidney function, as well as the recognition of such concomitant diseases as diabetes mellitus.

Microbiological diagnosis of osteomyelitis

The diagnosis and definition of etiology depends on the isolation of a pathogenic microorganism from places of damage to bone, blood or joint fluid. In patients with hematogenous form it is difficult to isolate the causative agent of the disease. In acute hematogenous form positive blood culture is noted in less than 50% of cases. Crops of fistula discharge are not reliable for predicting which microorganisms are in the affected bone. In a chronic variant of the disease, intrahospital infection is often associated, and sowing from fistula and ulcers in only half of the patients coincides with the true causative agent of bone infection. With polymicrobial microflora, the sowing from the fistula is even less informative. To determine the etiology of pathology, biopsy data are more important, which allows to determine the true causative agent of the disease in 75% of cases.

For timely isolation and identification of pathogenic microorganisms, it is proposed to use bacterioscopy, anaerobic techniques of bacteriological studies, gas-liquid chromatography, serological methods of identification of the pathogen. If antibiotics were prescribed to a patient prior to bacteriological examination, then the empirical regimen of therapy should be discontinued 3 days before taking culture samples to identify the causative agent of the disease.

X-ray diagnosis of osteomyelitis

In the hematogenous variant, radiologic changes usually reflect a destructive process, at least 2 weeks late in relation to the infectious process. In order to detect changes in the usual roentgenogram, a loss of 50 to 75% of the mineral substance of the bone matrix should occur. The earliest changes are edema, periosteal thickening or elevation and focal osteoporosis.

CT imaging provides a picture of the bone and surrounding soft tissue with a higher spatial and contrast resolution. Details of destruction of the cortical bone, periostitis and changes in soft tissues allow not only qualitative but also quantitative assessment of the bone state (osteodensitometry). Early findings can be intramedullary gas and increased bone marrow density. CT can be used to determine surgical tactics and to differentiate acute and chronic forms of the disease.

With chronic form of the disease, CT allows better visualization of bone sequestration, sequestral box, gas in the bone marrow canal and suppurative fines better than conventional radiography. The helical CT with multiplanar reconstruction is more efficient than the standard CT, since it allows to achieve optimum image quality while reducing the scan time by combining two thin sections - linear and spiral, which allows obtaining qualitative secondary reconstructions and significantly reducing the radiation load (up to 50%). . The three-dimensional reconstruction provides an opportunity to more accurately provide a picture of the sequestration of endostal growths. In addition, it allows you to identify parasseous fluid accumulations and sequestration.

Magnetic resonance imaging

MRI has a very high sensitivity and specificity in the diagnosis of osteomyelitis, exceeding the capabilities of CT. This method allows not only to identify bone pathology, but also to differentiate the infection of bone and soft tissues. Unlike CT and conventional radiography, MRI gives a fine contrasting multi-plane image of the bone marrow and soft tissues. With its help, it is possible to differentiate between infection of soft tissues adjacent to the bone, and true inflammatory changes in the bone marrow canal, which is often problematic in other studies.

MRI is an effective method of pre-surgical planning of surgical treatment, because with this technique it is possible to determine the length of nonviable tissues and the topography of anatomically important formations adjacent to the inflammatory focus, which allows to reduce the traumatic nature of surgical intervention and avoid complications during surgery.

Radionuclide diagnosis of osteomyelitis

Radionuclide diagnostics of osteomyelitis is used for early detection of the disease, determination of localization, prevalence and degree of development of the infectious process. The most commonly used bone scintigraphy with 11Tc. This diagnosis of osteomyelitis has a high sensitivity in the recognition of the disease, and the results can be obtained as early as the first day after the onset of the disease. At the same time, this technique is not specific enough to confirm the diagnosis, since isotope accumulation occurs not only in places of osteoblastic activity, but also in areas of increased concentration of polymorphonuclear leukocytes and macrophages, in malignant tumors and zones of increased blood flow. Radionuclide scanning with 99mTc is performed when the diagnosis is ambiguous or there is a need to assess the degree of inflammation.

Another method of radionuclide diagnosis of osteomyelitis is immunoscintigraphy using leukocytes. The principle of the method is based on the migration of leukocytes to the focus of inflammation. This study is superior to the methods described above and can be a method of choice in the diagnosis of osteomyelitis.

Ultrasonic diagnosis of osteomyelitis

Ultrasound is a reliable, non-invasive and informative method of identifying pus accumulation. With it, you can also identify soft tissue edema, irregularities and defects on the bone surface, bone callus, periosteal reaction, cortical sequesters and bone sequesters lying in soft tissues, fluid accumulation in the joint and paraarticular tissues.

Positron Emission Tomography

In recent years, work has appeared on the use of positron emission tomography for the diagnosis of osteomyelitis. It is based on the principle of accumulation of the ultrashort-lived isotope of fluorodeoxyglucose in the outbreak. The method allows to determine places of increased accumulation of phosphorilated products of fluorodeoxyglucose and thereby confirm or exclude this pathology.

Study of peripheral circulation

Inherent components of the pathogenesis of the purulent-inflammatory process are violations of intraosseous microcirculation and regional circulation. X-ray contrast angiography serves as an informative method for studying the roentgenotomy of the vascular bed, but its invasiveness, high cost, and relative limitations in the quantitative interpretation of the function of the distal vascular bed limit its use. This method is mainly used in the plastic surgery using flaps on the vascular pedicle. Regional blood circulation can also be assessed using ultrasound Doppler and duplex angioscanning. To evaluate microcirculation, they suggest using laser Doppler flowmetry, thermal imaging, and polarography. Percutaneous determination of oxygen and carbon dioxide tension helps to control blood circulation in the affected area and transplanted tissue grafts.