In-vivo degradation of poly(carbonate-urethane) based spine implants

Abstract

Fourteen explanted Dynesys® spinal devices were analyzed for biostability and compared with a reference, never implanted, control. Both poly(carbonate-urethane) (PCU) spacers and polyethylene-terephthalate (PET) cords were analyzed. The effect of implantation was evaluated through the observation of physical alterations of the device surfaces, evaluation of the chemical degradation and fluids absorption on the devices and examination of the morphological and mechanical features. PCU spacers exhibited a variety of surface damage mechanisms, the most significant being abrasion and localized, microscopic surface cracks. Evidence of oxidation and chain scission were detected on PCU spacers ATR–FTIR. ATR–FTIR, DSC and hardness measurements also showed a slight heterogeneity in the composition of PCU. The extraction carried out on the PCU spacers revealed the presence of extractable polycarbonate segments. One spacer and all PET cords visually exhibited the presence of adherent biological material (proteins), confirmed by the ATR–FTIR results. GC/MS analyses of the extracts from PET cords revealed the presence of biological fluids residues, mainly cholesterol derivatives and fatty acids, probably trapped into the fiber network. No further chemical alterations were observed on the PET cords. Although the observed physical and chemical damage can be considered superficial, greater attention must be paid to the chemical degradation mechanisms of PCU and to the effect of byproducts on the body.

The Study on Application of Biopolyols Obtained by Cellulose Biomass Liquefaction Performed with Crude Glycerol for the Synthesis of Rigid Polyurethane Foams

“…Generally, it can be seen that intensity of majority of signals is decreasing. A band at 1170 cm − 1 appears, which is attributed, among others, to bridging between polyol segments [53]. The decrease of the intensity of signal around 1310 cm − 1 suggests the conversion of urethane bond into ortho-aromatic amine ester structure via photo-Fries rearrangement [54].…”

A novel test method for quantifying cracking propensity of photovoltaic backsheets after ultraviolet exposure

“…The band at 1410 cm −1 for PET indicates in‐plane vibration of the phenyl ring that is insensitive to molecular orientation and conformation and is used as reference and normalization . Assignment of individual bands of PET can be found elsewhere . Difference spectra are generated by subtracting the normalized spectra of fresh samples from that of aged as shown in Figure C, D. Negative peaks indicate species deficit relative to the reference, and positive peaks are new species formation.…”

“…37 Assignment of individual bands of PET can be found elsewhere. 37,38 Difference spectra are generated by subtracting the normalized spectra of fresh samples from that of aged as shown in Figure 6C Figure 7B to D), the surface contracted and pigments compacted resulting in a fine aggregation surface. 43 On the other hand, in the presence of moisture ( Figure 7E to G), a much rougher surface was observed.…”

In vitro oxidative degradation of a spinal posterior dynamic stabilization device

“…Explanted orthopaedic implants, which contain PCU components, have demonstrated new absorbance peaks at 1650 cm −1 and/or 1174 cm −1 to demonstrate biological oxidative degradation . However, another explant study did not find new absorbance peaks linked to biological oxidative degradation .…”