Diagnosis of osteomyelitis

Currently, the diagnosis of osteomyelitis, clarification of the localization and extent of the lesion, as well as determination of the effectiveness of treatment are based on laboratory, bacteriological, morphological and radiation research methods, which can be conditionally divided into priority and additional.

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Laboratory diagnostics of osteomyelitis

Laboratory tests are useful in determining the inflammatory process and its severity. Numerous studies have shown that the white blood cell count is not a sensitive indicator. However, other markers of inflammation, such as ESR and C-reactive protein, although not specific, may be useful in patients suspected of having this pathology due to their sensitivity. The white blood cell count, ESR, and C-reactive protein concentration should be checked on admission and during treatment in all patients. Other laboratory tests can be used to monitor liver and kidney function and to recognize concomitant diseases such as diabetes mellitus.

Microbiological diagnostics of osteomyelitis

Diagnosis and determination of etiology depend on the isolation of the pathogenic microorganism from the sites of bone damage, blood or synovial fluid. In patients with the hematogenous form, it is difficult to isolate the causative agent of the disease. In the acute hematogenous form, positive blood cultures are noted in less than 50% of cases. Cultures of secretions from the fistula tract are not reliable for predicting which microorganisms are in the affected bone. In the chronic form of the disease, a hospital-acquired infection often joins in, and cultures from fistulas and ulcers only in half of patients coincide with the true causative agent of bone infection. In the case of polymicrobial microflora, cultures from the fistula are even less informative. Biopsy data are more important for determining the etiology of the pathology, which allow one to determine the true causative agent of the disease in 75% of cases.

For timely isolation and identification of pathogenic microorganisms, it is suggested to use bacterioscopy, anaerobic technique of bacteriological research, gas-liquid chromatography, serological methods of pathogen identification. If antibiotics were prescribed to the patient before bacteriological research, then to identify the pathogen of the disease, the empirical therapy regimen should be stopped 3 days before taking culture samples.

X-ray diagnostics of osteomyelitis

In the hematogenous variant, radiographic changes usually reflect a destructive process that lags behind the infectious process by at least 2 weeks. In order for changes to be detected on a conventional radiograph, a loss of 50 to 75% of the bone matrix mineral must occur. The earliest changes are edema, periosteal thickening or elevation, and focal osteoporosis.

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

In the chronic form of the disease, CT allows better visualization of bone sequestration, sequestral box, gas in the medullary canal and purulent leaks than conventional radiography. Spiral CT with multiplanar reconstruction is more effective than standard CT, as it allows achieving optimal image quality while reducing scanning time by combining two thin slices - linear and spiral, which allows obtaining high-quality secondary reconstructions and significantly reducing radiation exposure (up to 50%). Three-dimensional reconstruction allows for a more accurate presentation of the sequestration picture of endosteal growths. In addition, it allows for the determination of paraosseous fluid accumulations and sequesters.

Magnetic resonance imaging

MRI has a very high sensitivity and specificity in the diagnosis of osteomyelitis, surpassing the capabilities of CT. This method allows not only to identify bone pathology, but also to differentiate bone and soft tissue infections. Unlike CT and conventional radiography, MRI provides an excellent contrast multiplanar image of the bone marrow and soft tissues. It can be used 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 for preoperative planning of surgical treatment, since this technique can determine the extent of non-viable tissues and the topography of anatomically important structures adjacent to the site of inflammation, which reduces the trauma of surgical intervention and avoids complications during surgery.

Radionuclide diagnostics 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. Bone scintigraphy with 11Tc is most often used. This diagnostics of osteomyelitis has high sensitivity in recognizing the disease, and the results can be obtained already in the first day from the onset of the disease. At the same time, this method is not specific enough to confirm the diagnosis, since the accumulation of the isotope occurs not only in places of osteoblastic activity, but also in areas of increased concentration of polymorphonuclear leukocytes and macrophages, in malignant tumors and areas 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 diagnostics of osteomyelitis is immunoscintigraphy using leukocytes. The principle of the method is based on the migration of leukocytes to the inflammation site. This study is superior to the above methods and can be the method of choice in the diagnostics of osteomyelitis.

Ultrasound diagnostics of osteomyelitis

Ultrasound is a reliable, non-invasive and informative method for identifying purulent accumulations. It can also be used to identify soft tissue swelling, irregularities and defects on the bone surface, bone callus, periosteal reaction, cortical sequesters and bone sequesters located in soft tissues, fluid accumulations in the joint and paraarticular tissues.

Positron emission tomography

In recent years, there have been studies on the use of positron emission tomography for the diagnosis of osteomyelitis. It is based on the principle of accumulation of the ultra-short-lived isotope of fluorodeoxyglucose in the lesion. The method allows one to determine the sites of increased accumulation of fluorodeoxyglucose phosphorylation products and thereby confirm or exclude this pathology.

Peripheral Circulation Study

Integral components of the pathogenesis of the purulent-inflammatory process are disorders of intraosseous microcirculation and regional blood circulation. X-ray contrast angiography serves as an informative method for studying the X-ray anatomy 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 used mainly in plastic surgeries using flaps on a vascular pedicle. Regional blood circulation can also be assessed using ultrasound Dopplerography and duplex angioscanning. Laser Doppler flowmetry, thermal imaging, and polarography are proposed for assessing microcirculation. Transcutaneous determination of oxygen and carbon dioxide tension helps to control blood circulation in the affected area and transplanted tissue flaps.