Table 2.

Clinical Features and Findings Differentiating VOC From Osteomyelitis

Factor	VOC	Osteomyelitis
Prevalence	50× more common than osteomyelitis	—
History and physical examination
Fever	Fever (>38.0°C) is possible	Fever (>38.0°C) more likely to be identified for 24 hours before presentation
Location of pain	May have multiple sites of pain	More likely to have pain in a single area, usually the diaphysis of a long bone
Joint appearance	Joint swelling is possible	More likely to present with joint swelling
Laboratory testing
Leukocytes	Normal to mildly elevated	May be elevated
Inflammatory markers (CRP, ESR)	Normal to mildly elevated	Although not specific for osteomyelitis, more prominent elevations in CRP and ESR are found in osteomyelitis
Cultures	—	Benchmark diagnosis is a positive culture from bone, blood or synovial fluid
Imaging
Plain radiograph	Usually normal, but both conditions may show soft-tissue edema, periostitis, or osteopenia
MRI	—	Localized marrow abnormality of decreased marrow signal on T1-weighted images and increased signal on T2-weighted images

CRP = C-reactive protein; ESR = erythrocyte sedimentation rate; VOC = vaso-occlusive crisis