Comparison between Magnetically Controlled Growing Rods and Spinal Growth Guidance Surgery for Idiopathic Early Onset Scoliosis: A Three-Dimensional Analysis

Abstract

Study design: Retrospective Cohort.

Objective: Compare Spinal Growth Guidance surgery (SpGG) and Magnetically Controlled Growing Rods (MCGR) outcomes in idiopathic early-onset scoliosis (i-EOS) using Three-Dimensional True Spine Length (3D-TSL).

Summary of background data: SpGG and MCGR are techniques aimed to correct and control severe progressive spine deformity while maintaining growth. Past studies yielded comparable results between constructs using vertical coronal measures, which fail to account for growth outside plane of measurement due to 3-Dimensional deformity.

Methods: A multi-center database was queried for i-EOS patients undergoing MCGR or SpGG with minimum 2-year follow-up. Patients were included with perioperative and 2-year measurements.

Results: There were 161 patients (99 female; 31 SpGG/130 MCGR) mean age at surgery 8.1 years. 19.3% SpGG and 8.5% MCGR underwent repeat surgeries. SpGG reduced scoliosis from 67° to 26° postoperatively to 35° final (46% correction, P=0.02). MCGR reduced scoliosis 71° to 40° postoperatively to 42° final (34% correction, P<0.001). SpGG had greater coronal curve percent correction than MCGR at 2-year (P=0.03). SpGG maintained maximal measured kyphosis (MMK) preoperative to immediate postoperative with increase at follow-up (41° to 43° to 50°, P=0.004). MCGR initially decreased postoperatively (49° to 36°, P<0.001) with an increase at final (+6, 42°, P=0.002). There was a significant change in MMK between SpGG and MCGR (SpGG +9 vs. MCGR-7; P<0.001). Total cohort T1-S1 height increased (281 mm to 314 mm) and at 2-years (336 mm) (P<0.001). 3D-TSL didn't significantly change preoperative to immediate postoperative (338 to 342 mm) for either construct. At 2-year SpGG 3D-TSL increased 16.8 mm/y, while MCGR increased 14.2 mm/y (P=0.2).

Conclusions: At 2-year, 3D-TSL increased for 14.2 mm/y for MCGR and 16.8 mm/y for SpGG. Overall, SpGG and MCGR offer similar outcomes 2-years postoperatively as assessed by 3D-TSL. SpGG had greater coronal curve percent correction and maintained maximal kyphosis.

Keywords: Magnetically Controlled Growing Rods; Shilla Growth Guidance; T1-S1 length; Three-Dimensional Spine Length; idiopathic scoliosis; surgical correction.