Diagnostic Approach to Osteomyelitis

Clinical Assessment and Laboratory Studies

The American College of Radiology recommends performing a thorough medical and neurologic examination to identify potential sources of hematogenous seeding and assess motor/sensory function 2
The Infectious Diseases Society of America suggests obtaining two sets of aerobic and anaerobic blood cultures before starting antibiotics 2
Measurement of inflammatory markers, including C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR), is recommended by the American College of Radiology 1, 2
Procalcitonin (PCT) may be helpful when clinical examination is diagnostically equivocal, as suggested by the Diabetes/Metabolism Research and Reviews 1

The American College of Radiology recommends plain radiographs as the first imaging test for all patients with suspected osteomyelitis 3, 4
MRI with and without contrast is the preferred imaging modality when diagnosis remains uncertain after initial radiographs, with a sensitivity of 97%, specificity of 93%, and accuracy of 94% in diagnosing osteomyelitis, as reported by the Clinical Infectious Diseases journal 1, 2, 5
Characteristic findings on MRI include decreased T1-weighted bone marrow signal with increased signal on fluid-sensitive sequences, as described by the Journal of the American College of Radiology 3
A normal marrow signal on MRI reliably excludes infection, with a 100% negative predictive value, as reported by the Journal of the American College of Radiology 3

The Infectious Diseases Society of America recommends obtaining bone samples for culture, either intraoperatively or percutaneously, for definitive diagnosis 1, 6
Conventional microbiology techniques are preferred for first-line identification of pathogens, as suggested by the Diabetes/Metabolism Research and Reviews 1
Bone cultures are particularly indicated in patients with diabetic foot osteomyelitis when clinical and imaging evaluations yield uncertain diagnosis, soft-tissue cultures are inconclusive, or infection has failed to respond to initial empirical antibiotic therapy, as reported by the Radiology journal 5

For diabetic foot infections, the Diabetes/Metabolism Research and Reviews recommends using a combination of probe-to-bone test, plain X-rays, and inflammatory markers (ESR, CRP, or PCT) as initial diagnostic studies 1
For suspected vertebral osteomyelitis, the Clinical Infectious Diseases journal strongly recommends spine MRI 2
For chronic osteomyelitis, the Journal of the American College of Radiology suggests using CT to evaluate periosteal reaction, trabecular coarsening, bone fragmentation, cortical erosions, and fistulae 7
FDG-PET has shown 91% accuracy for detecting chronic osteomyelitis and may be particularly useful when hardware is present, as reported by the Journal of the American College of Radiology 7