Magnetic controlled growing rods for early-onset scoliosis: a 4-year follow-up

Abstract

Background context: There have been no studies with medium-term follow-up of magnetic controlled growing rods (MCGRs).

Purpose: This study aimed to report our single center experience of a magnetic growing rod system with an average of 4 years' follow-up.

Study design/setting: A retrospective case series was carried out.

Patient sample: The sample comprised patients with early-onset scoliosis treated with magnetic controlled growth rods who were operated in 2011.

Outcome measures: Cobb angle, spinal growth rate, complications, and revision were the outcome measures.

Methods: Clinical case notes and radiographs were reviewed.

Results: There were 8 patients (5 dual-rod construct, 3 single-rod construct) who had a minimum of 44 months' follow-up and average of 48 months (44-55 months). Mean age at surgery was 8.2 years (range 3-10). Mean preoperative Cobb angle was 60° (34-94), whereas mean postoperative Cobb angle was 42° (32-63). The average number of extensions was 13.8 (range: 12-20). There were 6 patients (75%) who required 8 revision surgeries: rod problems (N=4), proximal screw pull-out (N=3), and development of proximal junction kyphosis (N=1). All three patients who had single-rod construct underwent revision procedure. Currently, four patients (50%) still have the magnetic rods in situ. The mean duration of MCGR in the patient in the removed group was 39 months (range: 34-46).

Conclusions: Medium-term results of MCGR are not as promising as previously reported early results. Hence, MCGRs should be used with caution. Single-rod constructs should definitely be avoided. The role of MCGRs in revision cases still remains unknown.

Keywords: Early-onset scoliosis; MAGnetic Expansion Control system; Magnetic controlled growing rods; Medium-term follow-up; Revision; Survivorship.