Discussion of Osteomyelitis
- Osteomyelitis is a bone infection that can result from hematogenous spread or can be secondary to direct or contiguous inoculation.
- In young adults, it is most commonly associated with an open fracture or direct trauma.
- In elderly and pediatric patients, the cause of osteomyelitis is typically bacteremia.
- Disease states known to predispose patients to osteomyelitis include immunosuppression, diabetes mellitus, sickle cell disease, intravenous drug abuse, and alcoholism.
- The most commonly cultured pathogen is S aureus, although in HIV-infected patients, 30% of cases of osteomyelitis are due to atypical mycobacteria. *Blood culture results are positive in only 50% of patients with hematogenous osteomyelitis.
- In long bones, tuberculous osteomyelitis usually begins in the metaphysis and spreads to the epiphysis.
- The most common osseous site of disease is the spine (50% of cases, in particular, the thoracic spine.
- In addition to tuberculosis, the HIV-infected population is susceptible to bacillary angiomatosis, an unusual form of osteomyelitis that is associated with fever, anemia, hepatomegaly, splenomegaly, and well-defined nonsclerotic lytic lesions that are demonstrated at CT.
- Therapy for osteomyelitis involves
- Intravenous administration of antibiotics
- Referral of the patient to a surgeon and, possibly, to a medical infectious disease expert.
- Without the initiation of proper treatment, complications of osteomyelitis may ensue.
- Complications include the formation of a bone abscess, fracture, septic arthritis, and secondary cellulitis with draining soft-tissue sinus tracts.
- If acute osteomyelitis evolves into a chronic infection, significant pain and disability may result.
 Imaging Findings for Osteomyelitis
- Conventional radiographic evaluation of acute osteomyelitis is insufficient because bone changes are not evident for 14–21 days after the onset of infection.
- Although MR imaging is the accepted modality of choice for the early detection and surgical localization of osteomyelitis, in the emergency department, CT is usually more readily available for establishing the diagnosis.
- At CT, features of bacterial osteomyelitis include overlying soft-tissue swelling, periosteal reaction, medullary low-attenuation areas or trabecular coarsening, and focal cortical erosions.
Patient #1: Extensive calcaneal osteomyelitis. Note soft tissue ulceration and cellulitis
 See Also
 External Links
 References for Osteomyelitis
- Laura M. Fayad, John A. Carrino, and Elliot K. Fishman. Musculoskeletal Infection: Role of CT in the Emergency Department. RadioGraphics 2007 27: 1723-1736.