Retrieval Analysis of MCGRs
We are the worldwide retrieval centre for the analysis of Magnetically Controlled Growth Rods (MCGRs).
What are MCGRs?
Magnetically Controlled Growth Rods (MCGRs) are used in the surgical treatment of children with scoliosis; the rods serve to brace the spine and minimise the progression of scoliosis as the child grows.
An external magnet is used to extend the length (distract) of the rods, in-line with the growth of the child; this is performed at regular intervals, usually between 1 and 6 months in a routine outpatient ‘distraction clinic’ visit.
These rods are intended to be removed after they have been extended to their full length; these may be replaced with longer rods if the patient is still growing or the patient may undergo other treatment options if growth has stopped.
In the UK, one design of MCGR has been available for clinical use, known as the MAGnetic Expansion Control (MAGEC) rod (NuVasive). Since its first use in 2009, there have been 7 design iterations of the MAGEC rod, namely: MAGEC 1.0, 1.1, 1.2, 1.3, 2.0, 2.1 and most recently the MAGEC X (first used mid-2017).
What are the known issues?
On the 1st of April 2020, the manufacturer issued an FSN, voluntarily suspending the supply of all MAGEC rods to the UK, and the MHRA released an MDA the same day confirming this with the action that surgeons in the UK should not implant MAGEC rods until further notice.
On 25th March 2021, the European Notified body for the manufacturer temporarily suspended the CE certification of all MAGEC devices. This meant that the sale of these devices was not permitted in any country requiring a CE mark, including the UK which continues to recognise the CE system until 30th June 2023. The CE mark was reinstated on 19th November 2021with revised instructions for use.
These actions came as a result of previous FSNs and MDAs highlighting issues with a fracture/failure of external and internal components and the generation of titanium wear/corrosion debris, in some cases preventing rod distractions, ultimately requiring early and unplanned revision. The specific decision to suspend the CE mark entirely was due to the emergence of gaps in the technical documentation provided by the manufacturer to the notified body.
Following the CE mark being reinstated, the MHRA is now investigating whether the clinical benefits of using these rods continue to outweigh the risks for their use in the UK; this device remains unavailable for use in the UK.
What is the Implant Science Centre doing?
We receive institutional level funding by the manufacturer (NuVasive, San Diego, USA) to independently collect and analyse MAGEC rods that have been removed from patients.
Our aim is to better understand the mechanisms of failure in these devices and help surgeons improve their management of patients implanted with MAGEC rods.
We do this by collecting associated clinical and imaging data together with the removed rods in order to identify important surgeon, implant and patient risk factors for failure.
Blood Titanium Testing
Our ongoing research is working to establish the role of measuring titanium levels in blood samples from MCGR patients as a means of monitoring implant function. This research was recently awarded the prize of 'best scientific oral presentation' at the annual meeting of the British Scoliosis Society (BSS), held in Edinburgh, November 2022.
Read more on this research here.
To collaborate with us and send retrieved MAGEC rods to our centre for analysis, contact Dr Harry Hothi at harry.
Assessment of material loss of retrieved magnetically controlled implants for limb lengthening
A retrieval analysis of the Precice intramedullary limb lengthening system
Analysing a mechanism of failure in magnetically controlled spinal rods
Clinical and retrieval evidence for corrosion of spine implants