Abstract and Introduction
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.
Untreated septic arthritis and osteomyelitis in children may result in significant orthopedic morbidity because of potential physeal and epiphyseal cartilage injury. These patients require prompt care and potential surgical intervention to prevent complications such as growth disturbance related to physeal insult, epiphyseal osteonecrosis, premature arthritis, joint arthrodesis, and sepsis. Musculoskeletal MRI has been shown to be useful in the management of these patients by confirming and localizing the diagnosis of infection or establishing an alternative diagnosis for the symptoms. When septic arthritis or osteomyelitis are present, MRI further defines which cases should require surgical intervention and which can be managed medically. If diagnostic or surgical intervention is indicated, MRI provides a road map by defining the location and size of drainable abscesses.
At our institution, when patients present with characteristic clinical features of septic arthritis or osteomyelitis, pediatric orthopedic surgeons may perform diagnostic or surgical intervention without a preintervention MRI examination. This situation arises when preintervention MRI requires on-call sedation personnel and thus introduces treatment delay. When procedure findings validate clinical findings of infection (purulence or positive culture), these patients will be observed and treated appropriately with antibiotics. However, a subset of these patients will subsequently be referred for MRI when a high clinical suspicion of infection remains despite a negative result after intervention. Unfortunately, iatrogenic injury to the soft tissues or marrow before the MRI study may potentially confound our ability to accurately exclude infection or to diagnose alternative causes for the patient's symptoms.
Therefore, our purpose was to evaluate the diagnostic value and clinical impact of urgent MRI after recent diagnostic or surgical intervention in children with suspected osteomyelitis and septic arthritis.