Magnetically controlled growing rod treatment for early-onset scoliosis: analysis of 52 consecutive cases demonstrates improvement of coronal deformity.

ABSTRACT

Background: The purpose of this study was to report the radiographic results and complications of magnetically controlled growing rod (MCGR) treatment in patients with early-onset scoliosis (EOS). Methods: Patient records and radiographs from a consecutive series of patients treated with MCGR for EOS at two Swedish institutions were reviewed retrospectively. Radiographic analysis included Cobb angle, T1-T12 height, T1-S1 height, thoracic kyphosis, and lung height. Subgroup analyses were performed on primary versus conversion cases and single versus dual rods using one-way analysis of variance (ANOVA) and independent samples t-test. Results: Fifty-two cases treated with MCGR (24 single rods, 28 dual rods) were included from local surgical records into this cohort study, 32 primary and 20 converted from other growth friendly surgical treatment. Mean age at MCGR implantation was 7.4 (2.0-14.6) years old in the primary group and 9.3 (5.0-16.1) years old in the converted group. Mean follow-up time was 3.7 (2.0-7.6) years. Mean (standard deviation; SD) Cobb angle of the major curve changed from 62° (17°) preoperatively to 42° (16°) postoperatively to 46° (18°) at final follow-up (P<0.001). Mean (SD) overall thoracic kyphosis changed from 41° (19°) preoperatively to 32° (14°) postoperatively to 39° (17°) at final follow-up (P=0.018). Mean T1-T12 height was 177 mm (34 mm) preoperatively, 183 mm (35 mm) immediate postoperative and 199 mm (35 mm) at final follow-up (P=0.047). The mean T1-T12 height increased significantly in the primary group but not in the converted group. The number of surgeries was 114 (78 planned, 36 unplanned). The rate of unplanned surgeries did not differ significantly between single and dual rods. The total number of complications was 70 of which 38 were implant related. The overall mean complication rate was 1.4 (0-4). There were no significant differences in complication rates between subgroups. Conclusions: MCGR treatment enabled and maintained correction of spinal deformity while allowing spinal growth. There were no significant differences in complication rates or unplanned surgeries between the groups treated with single or dual rods.