The Performance of MAGEC X Spine Rods: A Comparative Retrieval Study

Study Design: Multicentre comparative analysis of explanted Spine Magnetically Controlled Growing Rods (MCGRs). Objectives: MAGEC X, the latest commercially available generation, was recalled in 2020 due to the risk of post-implantation separation of an actuator end-cap component. Currently, the supply of all MAGEC rods was temporarily suspended in the UK and the EU. Objective of this study is to compare the performance of the MAGEC X MCGR to the earlier MAGEC 1.3 design iteration, by means of retrieval analysis. Methods: Fifteen of both MAGEC X and MAGEC 1.3 rods were consecutively collected from five different hospitals following removal surgery and matched by time to removal. Clinical and implant data was collected for all MCGRs. Analysis comprised visual assessments of external damage, plain radiograph evaluations, force and elongation testing, MAGEC X end-cap torque testing and disassembly. Mann-Whitney U tests were used to statistically compare groups. Results: Rod distraction reached in vivo was significantly higher in the MAGEC 1.3 (P = .002). There was no statistically significant difference in the total external damage score (P = .870), maximum force produced (P = .695) or distraction reached during force test (P = .880). No pin fracture was detected. Elongation of stroke was mildly higher (P = .051) for the MAGEC X implants. One MAGEC X had evident end cap component loosening. Internal damage scores were mildly lower in the MAGEC X group. Conclusion: MAGEC X showed similar performance results than the previous design iteration MAGEC 1.3. End-cap component loosening was observed, with no major consequences on the internal mechanism.