Blood Titanium Analysis of Patients With MAGEC Spine Rods in the COVID-19 Environment

Magnetic Expansion Control (MAGEC) growth rods are used in the surgical treatment of children with scoliosis; the primary constituent metal alloy in these is titanium.

Since June 2019, the manufacturer has released two Urgent Field Safety Notices (FSN) relating to known issues with the function of the rods that increase the risk of early failure and unplanned revisions. The UK MHRA has issued two similar Medical Device Alerts (MDA) with the most recent MDA issued on 1st April 2020, stating that (1) MAGEC rods must not be implanted in the UK until further notice and (2) all patients already implanted with this device should be followed up as soon as is possible.

At the time of writing, hospitals across the world are facing incredible challenges in dealing with the COVID-19 pandemic. Due to this, virtually all planned clinic visits for MAGEC rod patients and X-ray appointments have been postponed to help reduce the risk of the virus spreading.

Recent retrieval studies have shown that mechanical wear and corrosion of these rods is common, with a risk that the debris generated is released into surrounding tissue. This wear and corrosion is thought to be the primary cause of implant failures and the underlying implant factors leading to the issuing of FSNs and MDAs.

Whilst titanium is known to be highly biocompatible, the baseline and toxic levels of this alloy in biological fluids are poorly understood. Additionally, a better understanding of blood titanium levels in patients with MAGEC rods may enable this to become a biomarker of wear and corrosion of the rods. This may help surgeons identify earlier those patients who may develop implant related problems.

Furthermore, in the current COVID-19 environment, a blood test to measure titanium levels may be one of the most suitable ways in which to continue patient monitoring (and identify those at greatest risk of implant related issues), in the absence of regular clinic visits.

Previous work from the RNOH involved a similar study investigating patients with titanium hip implants.