Pediatric Lyme Arthritis and the Overuse of MRI: A Retrospective Review of Imaging Appropriateness

Purpose: To assess the use of MRI in treating pediatric musculoskeletal infections, especially Lyme disease, and to determine whether ordering imaging trends point to overuse in situations that could be treated clinically without advanced imaging.

Methods/Materials: We conducted a mixed retrospective and prospective chart review of pediatric patients diagnosed with osteomyelitis, septic arthritis, or Lyme arthritis at Penn State Hershey Medical Center between January 1, 2014, and March 1, 2024. Inclusion criteria comprised patients with bone or synovial fluid culture obtained, relevant ICD-9/10 codes, or evaluation for suspected MSK infection by Pediatric Infectious Diseases. Variables that were extracted included imaging (e.g., X-ray, CT, MRI, US), culture results, therapies, and outcomes. Descriptive statistics and comparative analysis were used to evaluate the usage of MRI by type of infection and relationship to surgical intervention.

Results: Among 132 patients, 43 (33%) were diagnosed with Lyme arthritis, 41 (31%) with osteomyelitis, 15 (11%) with septic arthritis, and 33 (25%) with both osteomyelitis and septic arthritis. Overall, 124 (94%) underwent imaging; 65 (52%) received an MRI. Lyme arthritis is clinically distinct from other groups and is typically treated nonoperatively. However, MRI was still commonly used across the cohort. Among Lyme arthritis patients, 11/43 (26%) had an MRI performed, yet only 3/11 (27%) of these patients underwent surgery compared to 78% and 67% of osteomyelitis and septic arthritis cases, respectively. Thus, 73% of MRIs in the Lyme arthritis subgroup did not change the course of medical treatment and were retrospectively deemed potentially unnecessary.

Conclusions: Despite low rates of surgical intervention and distinct clinical features, MRI was widely employed in pediatric Lyme arthritis despite characteristic clinical features and low rates of subsequent surgical treatment. These results suggest overutilization of MRI in Lyme arthritis workup, entailing detriments, such as needless sedation, expense, and imaging load. Efforts to improve diagnostic stewardship initiatives can decrease the use of low-yield MRI in favor of clinical-laboratory risk stratification.