Wednesday, May 3, 2017

MAGEC (Part 2)

In the last posting the MAGEC system for Early Onset Scoliosis was introduced.  This system is a significant improvement when compared to Traditional Growing Rods, mainly due to the ability to lengthen the instrumentation without the need for anesthesia or a trip to the operating room.  The benefits of this device are easy to see, but was with any new technology there are some drawbacks or limitations.  The MAGEC device is a cutting-edge, high-tech magnetic lengthener and complicated devices may not function as intended.  The MAGEC device requires a magnetic field from the ERC (shown below) to spin the magnets in the implanted actuator.

It is possible the distance between skin and the actuator is too great, making the magnetic field too weak to lengthen the actuator

 This can happen, in children with more subcutaneous fat, an older patient and if the actuator was deeply buried in soft tissues around the spine.  Personally I have had only one patient in whom the MAGEC device was unable to be magnetically lengthened.  The remaining 30+ patients in my practice with this device have been easy to lengthen.

The other problem with the MAGEC device was in breakage of the actuator pin.  If this happens the actuator will not lengthen with the ERC.  Several reports of actuator pin breakage have surfaced, with most of them being from Asia and Europe.  This is because the MAGEC system was first released overseas so there is a slightly longer experience with this device outside of the U.S.  This was also the first-generation of the MAGEC device.  When the MAGEC device was released in the U.S. the actuator pin design had been improved, creating a second-generation.  This is what we currently use in the U.S.  I have not seen any actuator pin breakage yet in my patient population. 

Another mode of failure of the MAGEC device is rod breakage, either above or below the actuator.  This type of failure is the same as what is seen in Traditional Growing Rods.  The metal rods are constantly stressed, or cycled, by the child on a daily basis.  These stresses are cumulative on the rods and will gradually weaken until there is a fracture or breakage of the rod. 


This problem can be partially avoided by using the larger sizes of the MAGEC rods, specifically the 5.5 mm rods instead of 4.5 mm rods.  However, due to patient size we cannot use 5.5 mm rods as the patient is just too small to hide the rods in their back without breaking through the skin or being painful.

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