Musculoskeletal ImagingHaematogenous osteomyelitis
an infection of bone or bone marrow occurring via spread of microorganisms through the
vascular system. The blood supply in
tubular bones is significant in this disease because differences in the
vascular pattern at different ages lead to different presentations in the infant, child and adult (Table 1).
Haematogenous ostemyelitis, Table 1. Patterns of involvement in haematogenous osteomyelitis according to age.
| Infant | Child | Adult |
| Localization | Metaphpyseal with epiphyseal extension | Metaphyseal | Epiphyseal |
| Involucrum | Common | Common | Not common |
| Sequestrum | Common | Common | Not common |
| Joint involvement | Common | Not common | Common |
| Soft tissue abscess | Common | Common | Not common |
| Pathologic fracture | Not common | Not common | Common * |
| Sinus tracts | Not common | Varible | Common |
* In neglected cases.
In persons with haematogenous osteomyelitis, when infection penetrates the periosteal membrane, a cloaca may form and extend into the adjacent soft tissues. Cortical sequestration can subsequently appear. In infants and young children, a suppurative process of the metaphysis may extend into the epiphysis and also lead to involucrum formation. Other abnormalities include single or multiple Brodies abscesses, usually of staphylococcal origin. On radiographs these abscesses appear as areas of radiolucency with adjacent sclerosis. In the metaphysis, the lucent region may connect with the growth plate by a tortuous channel (i.e. channel or tract sign); in the diaphysis, the radiolucent abscess cavity can be located in central or subcortical areas or in the cortex itself and may contain a central sequestrum; in an epiphysis, a circular, well-defined osteolytic lesion is seen. A cortical abscess simulates the appearance of an osteoid osteoma or a stress fracture. CT scanning and MR imaging are helpful for assessing the extent of the abscess. Sclerosing osteomyelitis may also occur in the subacute and chronic stages of osteomyelitis, with extensive periosteal bone formation surrounding the altered cortex. Considerable radiodensity and contour irregularity are seen in the affected bone.
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