The Fluoroscopic Technique for Monitoring Distraction of a Non-Invasive Lengthening Device in Early Onset Scoliosis

摘要

Study Design:Prospective non-randomised.Objective:To evaluate radiation exposure using fluoroscopy compared to x-rays in the monitoring of a growing rod system.Background:The integrity of implants in the treatment of early onset scoliosis (EOS) is usually monitored with repeatedplain x-rays. The cumulative dosage of ionizing radiation may be high. Children are highly sensitive to the carcinogeniceffects of radiation and have a longer life span in which to reflect this risk. Fluoroscopy is commonly used to obtainfocused images in other areas of orthopaedics. It has the advantage of less radiation intensity due to flash exposure. Wehave used fluoroscopy to monitor the lengthening of a non-invasive growing rod system in the treatment of EOS. Wereport on the results.Methods:The technique was initially refined in vitro by performing an audit in which 10 radiographers screened aphantom spine (Plastic dummy) with an implanted non - invasive growing rod device. Pulse rate setting was 3. Averageexposure time was 0.01 seconds. Average radiation dose was 0.04 μGym2. A plain x-ray of the same phantom spineyielded a radiation dose of 0.5 μGym2.Radiation exposure using fluoroscopy was compared to that received using plain radiographs in ten consecutive patientstreated for EOS. There were 8 males and 2 females. Average age 5.2 years.Results:Mean radiation exposure using fluoroscopy was 0.0046 mSv compared to an average radiation exposure of 0.115mSv using standard x-rays (p<0.003). Mean cancer induction risk was calculated to potentially reduce from 1:225,000 to1:4.9 million.Conclusion:We would recommend fluoroscopy as a useful technique to monitor the lengthening of a non-invasivegrowing rod system due to the significantly smaller radiation exposure.