The use of a polyetheretherketone (PEEK) cervical disc allows for significantly improved visualisation of surrounding spinal and neuro structures on postoperative magnetic resonance imaging (MRI) scans compared to metal implants.
This is according to results presented by Domagoj Coric (Carolina Neurosurgery & Spine Associates, Charlotte, USA) at the International Society for the Advancement of Spine Surgery Annual Meeting (ISASS20; 26–28 February, Puerto Rico, USA).
At the ISASS meeting, Coric presented results from the first Investigational Device Exemption (IDE) trial to assess a PEEK-ceramic cervical disc arthroplasty (CDA) implant, the Simplify Disc (Simplify Medical), which compared MRI artefacts from the investigational device to that of four CDA devices that are currently on the market.
Coric said that the presence of significant metallic components in existing CDA devices leads to MRI artefacts which can obstruct important anatomy including the neural foramen and spinal cord, causing potential difficulties in postoperative diagnosis. Spinal implants comprised of PEEK have gained favour, he said, in part due to the reduced MRI artefacts. The first PEEK/ceramic CDA is currently undergoing US Food and Drug Administration (FDA) IDE trials, and comparison of MRI artefacts between different CDA devices has not been previously reported in the literature, Coric noted.
The results indicate that the devices produce statistically smaller MRI artefacts in comparison to other approved devices composed of titanium and polyurethane, titanium and ultra-high molecular weight polyethylene (UHWMPE), CCM and UHMWPE, or a Ti-ceramic composite. The study team carried out a retrospective review of patients that received a CDA device at one or two contiguous levels and a postoperative MRI from three centres participating in the PEEK/ceramic CDA device IDE trials.
MRIs were performed on 1.5T MRI machines and included axial T1-weighted, axial T2-weighted, sagittal STIR, sagittal T1-weighted, and sagittal T2-weighted views. The artefacts were measured by a radiologist blinded to the CDA device. Artefact was defined as the distance between the device boundary and the fringe of the artefact in the anterior-posterior (AP) direction (ASTM F2119); calculated as half the difference between the maximum measured AP distance of the artefact minus the AP footprint of the CDA device.
A total of 46 CDA devices comprised of titanium/polyurethane (five levels), titanium/UHMWPE (10 levels), CCM/UHMWPE (15 levels), titanium ceramic composite (five levels), and the investigational PEEK/ceramic composition (11 levels) were evaluated. The investigational PEEK/ceramic device’s artefacts, Coric said, were statistically significantly smaller (p<0.05) than those of other evaluated devices, measuring at ≤0.8mm compared to a range of 3.2–6.3mm for the other devices.