MSCT-semiotics of pin tract osteomyelitis

Introduction Inflammation at the wire tract sites in patients treated with transosseous osteosynthesis is one of the most common complications. Bone manifestations of inflammation are quite common in clinical practice, yet characteristic radiographic findings have not been well described.

The aim of this study was to identify the nature of radiographic bone changes in patients with pin tract osteomyelitis at various inflammatory sites.

Materials and Methods The study included 22 patients with chronic pin tract osteomyelitis (PTO) that developed following transosseous osteosynthesis with the Ilizarov fixator. To assess structural bone changes, multislice computed tomography (MSCT) was used, including analysis of axial sections and multiplanar reconstructions (MPR) in the sagittal and coronal planes of the femur and tibia. Bone density (Hounsfield units, HU) in the inflammation area was quantitatively assessed, and the morphology of the wire tract canals (width, wall contours, and the presence of sequesters) was analyzed to identify patterns relevant for treatment decisions.

Results The data obtained indicate the presence of specific radiographic manifestations of osteomyelitis, characteristic of chronic osteomyelitis of any origin, especially in the late stages of inflammation. The most prominent symptoms of osteomyelitis in the early stages include characteristic changes in the wire tract canals: widening and blurring of the contours, increased density, and the appearance of periostitis around the wire tract. Wire canals in the metaphyseal regions are characterized by increased wall density and low density of the canal contents. In the diaphysis, the wire canals have walls with irregular contours and no density differences from the cortical plate. Small sequesters featuring the density of 650–700 HU are often visualized within the canal. "Walled-in" sequesters are also characteristic of pin tract osteomyelitis in the diaphysis.

Discussion The literature has devoted considerable attention to soft tissue inflammation, its prevention, and treatment methods during transosseous osteosynthesis. However, the radiographic semiotics of pin tract osteomyelitis have been limited, primarily presenting clinical cases without detailed analysis of bone changes. Pin tract osteomyelitis is characterized by general manifestations of osteolysis and increased density of the wire canal contours. A distinctive feature of pin tract osteomyelitis in the diaphysis is the presence of "button-shaped" sequesters, confirmed by MSCT. Information on the location and nature of the changes allows clinicians to more effectively plan the extent of surgical intervention and select the optimal treatment strategy, taking into account the characteristics of the lesion and bone condition.

Conclusion Wire tract canals in the metaphyseal regions are characterized by increased wall density. In the diaphysis, the wire tracts are wider than in the metaphysis, with walls of irregular contours and no density differences with the cortical plate. Sequestra in the metaphysis have half the density of those in the diaphysis and vary in shape and size.

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