Background: There is speculation that use of magnetic resonance imaging (MRI) can increase the risk of pin site infection in patients with external fixation due to heating of the fixator pins, but no studies have evaluated this association with a large cohort of patients. This study compared pin site infection and external fixator complications in trauma patients with and without MRI exposure who also had extremity or pelvic fixation.
Methods: Following IRB approval, we conducted a retrospective chart review for 915 trauma patients admitted between January 2000 and December 2011 who underwent external fixation placement. Patients with LISS and llizarov fixators were excluded. Age, gender, date of service Injury Severity Score (ISS), and fracture classification (Gustillo) were abstracted, as were the following external fixation variables: location, date of placement, date of removal, exposure of fixator to MRI and hospital discharge date. Complications, including pin site infection, wound infection, skin necrosis, pin displacement and non-union were recorded. Logistic regression was used to determine if patients undergoing an MRI were more likely to experience a pin-site infection or complication, after adjusting for patient demographic variables.
Results: Demographic results were as follows: 64.5% male, median age = 44, and median ISS = 10. Overall, 12.9% of patients developed pin-site infections, and 24.7% developed one or more complications. Pin-site infection was not associated with MRI exposure (OR 0.64, 95% CI 0.22 - 1.51, p=0.35). The odds of developing a complication were also not associated with exposure to MRI (OR 1.51, 95% CI 0.84 -2.63, p= 0.14), and did not change when adjusted for fracture classification (OR 1.37, 95% CI 0.79 - 2.36, p = 0.26).
Conclusion: MRI obtained in the presence of external fixator devices does not appear to increase the incidence of pin site infections or complications.