Magnetically Controlled Growing Rods for the Management of Early-onset Scoliosis: Results and Complications at 3-year Follow-up

Abstract

Introduction A new method for the management of early-onset scoliosis (EOS) has been recently introduced: it consists of a magnetically controlled growing rod (MCGR) that allows gradual outpatient distractions under control of an external remote device. We present a series of 14 patients with EOS managed with MCGR (Ellipse TM MAGEC System, Irvine, CA). Material and Methods We implanted MCGR in 14 patients affected by EOS with various etiology. Scoliosis and kyphosis angles, T1-T12 and T1-S1 length were evaluated preoperatively, postoperatively, and at the last follow-up. A visual analogue scale score was used to evaluate pain during outpatient rod distraction procedures. The mean follow-up is 34 months. All patients attended distractions of the magnetic rod through an external remote control every 3 months. The mean predicted distraction was 3 mm at each lengthening session. Results The mean Cobb angle value was 64.7 ± 17.4 degrees (range, 45 to 100 degrees) preoperatively and 28.5 ± 13.9 degrees (range, 15 to 59 degrees) at the latest follow-up. The mean T1-S1 length value was 27.1 ± 5.4 cm (range, 16 to 34.8 cm) preoperatively and 32.8 ± 4 cm (range, 26.5 to 39 cm) at the latest follow-up. The mean T1-T12 length value was 16.2 ± 2.7 cm (range, 10 to 19 cm) preoperatively and 20.6 ± 2.9 cm (range, 15.5 to 23.5 cm) at the latest follow-up. The average monthly T1-T12 height increase was 0.8 mm, whereas the average monthly T1-S1 increase was 0.9 mm. Two patients experienced a rod breakage and 1 patient had a pull-out of the apical hooks. In cases of rod breakage, the magnetic rod was removed and replaced. In case of pull-out, apical pedicle screws have been positioned in substitution of hooks. Conclusion Although implant-related complications could occur, as in all EOS growing rods procedures, MCGR can be effectively used in patients with EOS. This spinal instrumentation can overcome many of the complications related with the traditional growing rods implants. In our experience, rod breakage occurred only in patients with a single magnetic rod instrumentation. First case was a patient with a severe thoracic kyphosis. In effect, the management of kyphosis with the MCRG is quite challenging. Moreover, a marked kyphosis was also the cause of pull-out of the apical hooks. Instead, in the second case of rod breakage, we reported a failure of the internal magnet of the rod. In conclusion, this procedure can be effectively used in outpatient settings, minimizing surgical scarring, surgical site infection, and psychological distress due to multiple surgeries needed in the traditional growing rods system, improving quality of life, and saving health care costs.