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

Abstract

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.

Pin Fracture in Magnetically Controlled Growing Rods: Influence of the Year of Manufacture

“…The latest design iteration was withdrawn from the market due to the risk of separation of the newly designed end-cap component. 13 The junction is also responsible for isolating the rod's internal mechanism from the patients' fluids and tissues. We cannot establish if it is the pin fracture or the failure of this junction that is the primary mechanism of failure, yet we speculate the 2 phenomena to be intertwined.…”

“…The junction in this region gained particular interest lately, as the manufacturer developed a new design iteration with an end-cap component probably aimed at enhancing its performance. The latest design iteration was withdrawn from the market due to the risk of separation of the newly designed end-cap component 13 . The junction is also responsible for isolating the rod’s internal mechanism from the patients’ fluids and tissues.…”

“…Following the evaluation of pin fracture, rods underwent functional evaluation, using previously published methods. 13 The maximum force and the elongation exerted during force testing were recorded, a manual elongation test was performed and the maximum extension was noted, and finally, the overall functionality of the implant was evaluated upon disassembly, after accurate pin fracture examination. Implants not able to elongate were deemed non-functional.…”