Safety of Magnetic Resonance Imaging in Orthopaedic Trauma Patients with External Fixation: A Two Center Case Series.

OBJECTIVES: To report on adverse events during magnetic resonance imaging (MRI) on patients with external fixators. METHODS: Design: Retrospective case series. Setting: Two Level 1 Trauma Centers. Patient Selection Criteria: Patients with external fixators on the appendicular skeleton or pelvis undergoing MRI between January 2005 and September 2023. Outcome Measures and Comparisons: Adverse events, defined as any undesirable event associated with the external fixator being inside or outside the MRI bore during imaging, including: (subjective) heating, displacement or pullout of external fixator, or early MRI termination for any reason. RESULTS: Ninety-seven patients with 110 external fixators had at least one MRI with an external fixator inside or outside of the MRI bore. The median age was 51 years (IQR: 39 – 63) and 56 (58%) were male. The most common external fixator locations were the ankle (24%), knee (21%), femur (21%), and pelvis (19%). The median duration of an MRI was 40 minutes (IQR: 26 – 58), 86% were performed using 1.5 Tesla MRI, and 14% were performed using 3.0 Tesla MRI. Ninety-five percent of MRI were performed for the cervical spine/head. Two MRI scans (1.6%), one of the shoulder and one of the head and cervical spine, with the external fixator outside of the bore were terminated early due to patient discomfort. There were no documented events of displacement or pullout of the external fixator. CONCLUSIONS: These findings suggest that MRI of the (cervical) spine and head can be safely obtained in patients with external fixators on the appendicular skeleton or pelvis. Given the low numbers of MRIs performed with the external fixator inside the bore, further studies are necessitated to determine the safety of this procedure. The results from this study can aid orthopaedic surgeons, radiologists, and other stakeholders in developing local institutional guidelines on MRI scanning with external fixators in situ. LEVEL OF EVIDENCE: Prognostic Level lV. See Instructions for Authors for a complete description of levels of evidence.