Value of MRI After Recent Diagnostic or Surgical Intervention in Children with Suspected Osteomyelitis

OBJECTIVE. The purpose of our study was to evaluate the diagnostic efficacy and impact of emergent MRI after recent intervention in children with suspected osteomyelitis or septic arthritis. MATERIALS AND METHODS. This retrospective case-control study in children with suspected osteomyelitis or septic arthritis consisted of 34 study subjects (mean age, 5.3 years) who underwent MRI after intervention and 96 control subjects (mean age, 8.7 years) who underwent MRI without prior intervention. Final diagnosis and management were abstracted from medical records. Consensus MRI review of the study group was performed to evaluate whether objective MRI criteria of osteomyelitis can be applied to patients who have undergone prior intervention. RESULTS. For the study and control groups, no difference was seen in the final diagnosis of osteomyelitis (26.5% [9/34] and 29.2% [28/96], p = 0.76), osteomyelitis or septic arthritis (41.2% [14/34] and 37.5% [36/96], p = 0.70), cellulitis or pyomyositis (20.6% [7/34] and 34.4% [33/96], p = 0.13), and noninfectious conditions (23.5% [8/34] and 13.5% [13/96], p = 0.17). Objective MRI criteria for osteomyelitis were present in all nine patients with a final diagnosis of osteomyelitis and were not present in the remaining 25 who did not have a final diagnosis of osteomyelitis despite recent intervention. Repeat interventions were necessary in the study group at a rate not significantly different from single interventions in the control group (29.4% [10/34] and 27.1% [26/96], p = 0.79). CONCLUSION. Iatrogenic soft-tissue and bone edema related to recent intervention in children with suspected osteomyelitis or septic arthritis does not affect the diagnostic efficacy of MRI. Performing MRI before intervention adds efficacy to patient management, prevents unnecessary interventions, and guides surgical procedures when indicated.