Preliminary comparison of primary and conversion surgery with magnetically controlled growing rods in children with early onset scoliosis

Purpose Non-invasive distraction of magnetically controlled growing rods (MCGR) avoids repeated surgical lengthening in patients with early onset scoliosis, but it is not known how effective this technique is in previously operated children. Methods In a retrospective, multicentre study, the data were obtained for 27 primary (P) patients [mean age 7.0 (2.4-10.7) years at surgery] and 23 conversion (C) patients [mean age 7.7 (3.6-11.0) years at conversion from standard growing rods] with 1-year follow-up. Results The mean major curve was 63.9 degrees in the P group and 46.5 degrees in the C group at baseline (preoperatively, p = 0.0009) and 39.5 degrees and 39.6 degrees, respectively, at 1-year follow-up (p = 0.99). The mean percentage change of spinal growth from baseline to 1-year follow-up was 18.3 % in the P group and 6.5 % in the C group (p = 0.007). Comparing the spinal growth from postoperative to 1-year follow-up no statistical difference was observed between the study groups (1.8 % P vs -2.2 % C, p = 0.09). Conclusions Scoliosis can be equally controlled after conversion from traditional growing rods into MCGR, but spinal growth from baseline is less in the conversion patients as compared with the primary group. Level of evidence III.