3-Year follow-up of a single magnetically controlled growing rod with contralateral gliding system and apical control for early onset scoliosis

STUDY DESIGN: Two-center retrospective cohort study.

OBJECTIVE: The aim of this study is to investigate the clinical effectiveness and safety of the MCGR hybrid in terms of spinal growth, 3D correction, balance, and complications. The magnetic-controlled growing-rod (MCGR) growth instrumentation method has gained popularity for early onset scoliosis (EOS) treatment in the past years due to the non-invasiveness of the subsequent interval elongation procedures. To improve 3D correction and reduce the costs, we combined a single concave MCGR with a sliding rod on the convex side to control the apex.

METHODS: A retrospective cohort study of 18 EOS children with an average 3-year follow-up (range 2.0-3.7) from two European spine centers treated with the single MCGR hybrid concept; 14 primary and 4 conversion cases. The primary and conversion cases were both evaluated preoperatively, postoperatively, 1 year, 2 years, and last follow-up.

RESULTS: Mean age was 9.9 (SD ± 2.9 years). The average frontal Cobb angle was reduced from mean 65° to 30° postoperatively, and had increased to 37° at latest follow-up. Rotation of the apical vertebra improved from mean 27° to 20° postoperatively which was partially lost to 23°. Kyphosis and lordosis both increased by an average of 5° during the time of follow-up. Spinal balance was improved. The post-implantation T1-S1 spine growth rate averaged 10 mm/year at last follow-up. There were 13 implant-related complications in 6 out of 18 patients. No screw pull-outs and nor surgical site infections were registered.

CONCLUSIONS: This is the first medium-term results of a single MCGR hybrid construct. Maintenance of correction and growth are reasonable, and the complication rate is relatively low as compared to bilateral MCGR application.

LEVEL OF EVIDENCE: III.