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A pilot cadaveric study of temperature and adjacent tissue changes after exposure of magnetic-controlled growing rods to MRI



To test for possible thermal injury and tissue damage caused by magnetic-controlled growing rods (MCGRs) during MRI scans.


Three fresh frozen cadavers were utilized. Four MRI scans were performed: baseline, after spinal hardware implantation, and twice after MCGR implantation. Cross connectors were placed at the proximal end and at the distal end of the construct, making a complete circuit hinged at those two points. Three points were identified as potential sites for significant heating: adjacent to the proximal and distal cross connectors and adjacent to the actuators. Data collected included tissue temperatures at baseline (R1), after screw insertion (R2), and twice after rod insertions (R3 and R4). Tissue samples were taken and stained for signs of heat damage.


There was a slight change in tissue temperature in the regions next to the implants between baseline and after each scan. Average temperatures (°C) increased by 0.94 (0.16–1.63) between R1 and R2, 1.6 (1.23–1.97) between R2 and R3, and 0.39 (0.03–0.83) between R3 and R4. Subsequent histological analysis revealed no signs of heat induced damage.


Recurrent MRI scans of patients with MCGRs may be necessary over the course of treatment. When implanted into human cadaveric tissue, these rods appear to not be a risk to the patient with respect to heating or tissue damage. Further in vivo study is warranted.

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This research was supported by Ellipse Technologies, Inc. We gratefully acknowledge the contribution of the Northwell Health Bioskills Education Center for their facilities and support staff.

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Correspondence to Selina Poon.

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Research Grant from Ellipse Technologies, Inc. Dr. Poon has received a speaker’s fee from Nuvasive. The rest of the author’s do not report any financial disclosures.

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Poon, S., Nixon, R., Wendolowski, S. et al. A pilot cadaveric study of temperature and adjacent tissue changes after exposure of magnetic-controlled growing rods to MRI. Eur Spine J 26, 1618–1623 (2017).

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  • Early onset scoliosis
  • Growing rods
  • Magnetic-controlled growing rods
  • Scoliosis
  • Magnetic resonance imaging