Aim:. The aim of this study was test the amount of corrosion occurring at the (Ti) /cobalt chrome (CoCr) interface comparing this with Ti and Ti interfaces. This was compared with retrieved metal work visualised under a scanning electron microscope (SEM). Methods:. The interface of interest is the interface between rod and the screw. We investigated corrosion seen at that interface with a CoCr rod coupled to a Ti screw versus a Ti rod coupled to a Ti screw (6 screws were used) Implants were loaded according to the ASTM F2193 – 02 Standard Specifications and Test Methods for Components Used in the Surgical Fixation of the Spinal Skeletal System. Pitting potentials were monitored using cyclic potentiodynamic polarization tests (ASTM F2129 – 08 Standard Test Method for Conducting Cyclic Potentiodynamic Polarisation Measurements) to determine corrosion susceptibility. Retrieved implants were visualised under (SEM) to confirm corrosion. Results:. Mean fretting current for titanium and cobalt chrome was 7.94 (μA) and for titanium on titanium 5.89 (μA). The results of SEM showed evidence of fretting and galvanic corrosion. Discussion:. Cobalt chrome ions in hip implants have raised concern amongst the orthopaedic community. This study showed that metal ion production occurs due to fretting and galvanic corrosion. This corrosion is increased in cobalt chrome and titanium constructs but statistically more tests are required to confirm this. Further research is required to understand this interface as cobalt chrome ions pose a potential hazard to patients with their reproductive years ahead. Conflict Of Interest Statement: No conflict of interest

Abstract

MAGnetic Expansion Control (MAGEC) rods are used in the surgical treatment of children with early onset scoliosis. The magnetically controlled lengthening mechanism enables rod distractions without the need for repeated invasive surgery. The CE certification of these devices was suspended in March 2021 due, primarily, to performance evidence gaps in the documents provided by the manufacturer to regulators and notified bodies. MAGEC rods are therefore not permitted for use in countries requiring CE marking. This was a survey of 18 MAGEC rod surgeons in the UK about their perception of the impact of the CE suspension on the clinical management of their patients. Unsurprisingly, virtually all perceived a negative impact, reflecting the complexity of this patient group. Reassuringly, these surgeons are highly experienced in alternative treatment methods.

Cite this article: Bone Jt Open 2022;3(2):155–157.

Aims

Magnetically controlled growing rod (MCGR) systems use non-invasive spinal lengthening for the surgical treatment of early-onset scoliosis (EOS). The primary aim of this study was to evaluate the performance of these devices in the prevention of progression of the deformity. A secondary aim was to record the rate of complications.

Aims

We present a case series of five patients who had revision surgery following magnetic controlled growing rods (MGCR) for early onset scoliosis. Metallosis was found during revision in four out of five patients and we postulated a mechanism for rod failure based on retrieval analysis.