Background: MRI is the gold standard in the radiographic diagnosis of pediatric osteomyelitis (OM). Plain film is recommended in the work-up but has low sensitivity in acute disease. The optimal role of x-ray in the diagnosis of OM in pediatrics is unclear.
Methods: We performed a retrospective chart review of patients diagnosed with OM from 2011 to 2015. Criteria were applied to capture healthy children with long bone OM. We divided patients into acute (symptoms ≤14 days) and sub-acute (>14 days) groups. We recorded age, duration of symptoms, infection location, WBC count, CRP, ESR, and culture results. We noted the presence of soft tissue and bone abnormalities on x-rays. MRI findings included the presence of complicated disease. We compared acute and sub-acute OM. We determined whether abnormal plain films were associated with clinical findings and a higher likelihood of complicated disease.
Results: 89 of 368 patients were included. 81 had acute OM, 8 sub-acute. 62.3% of patients with acute OM had positive blood cultures. Surgical cultures were positive in 85.2% of acute OM. Mean CRP was 11.4mg/dl (acute) and 4.2 (sub-acute). Mean ESR 60.6mm/hr (acute) and 63 (sub-acute). Mean WBC 13.4 (acute) and 10.2 (sub-acute). For acute OM, mean CRP for MSSA and MRSA was 11.9 and 18.2; mean ESR for MSSA and MRSA was 67.2 and 83.7. 84 patients had x-rays obtained. 35 (42%) were abnormal (57% soft tissue, 43% bone abnormalities). Sub-acute patients were more likely to have bony changes on x-ray versus acute (71% vs 13%). Soft tissue findings on x-ray were more common in acute OM due to MRSA vs MSSA (39 vs 26%) but there was no difference in presence of bony abnormalities. 3 of 4 cases with DVT had MRSA. 75% of patients with bony abnormalities on plain film had corresponding bony complications on MRI.
Conclusion: Patients with sub-acute OM were more likely to have abnormal bony findings on plain film. However, a surprising number of patients with acute disease had abnormal plain films, including bony findings. Bony findings on x-ray correlated with bony complications on MRI. Plain films continue to play a valuable role in the diagnostic workup of OM.
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