A novel method to eliminate the influence of absorbed lipids on the characterization of ultra-high molecular weight polyethylene using Fourier-transform infrared spectroscopy

Article type: Research Article

Authors: Sakoda, Hideyuki^a; | Sugano, Nobuhiko^b | Okamoto, Yoshihiro^a | Haishima, Yuji^a

Affiliations: [a] Division of Medical Devices, National Institute of Health Sciences, Kawasaki, Kanagawa, Japan | [b] Department of Orthopaedic Medical Engineering, Osaka University Graduate School of Medicine, Suita, Osaka, Japan

Correspondence: [*] Corresponding author: Hideyuki Sakoda, Division of Medical Devices, National Institute of Health Sciences, 3-25-26 Tonomachi, Kawasaki 210-9501, Japan. Tel.: +81 44 270 6726; Fax: +81 44 270 6726; E-mail: sakoda@nihs.go.jp

Abstract: BACKGROUND:Fourier-transform infrared spectroscopy (FTIR) is one of the standard methods to analyze ultra-high molecular weight polyethylene (UHMWPE) in orthopedic implants. For retrieved components, lipid extraction using an organic solvent prior to the measurement is necessary to eliminate the influence of lipids absorbed in vivo. However, its influence on the measurement has not been substantially investigated. OBJECTIVE:To investigate the influence of lipid extraction on the FTIR analysis of UHMWPE and to develop a novel method to obtain reliable results without inconvenient lipid extraction. METHODS:FTIR analysis was repeatedly performed on UHMWPE specimens from retrieved components before and after lipid extraction under various conditions. A method to calculate the extent of influence of the absorbed lipids from the FTIR spectra was developed using a peak separation technique. RESULTS:An elevated temperature was necessary for lipid extraction; however, it had the potential to influence the results if the conditions were not properly controlled. The results obtained using the peak separation technique coincided with those obtained after lipid extraction. CONCLUSION:The use of the peak separation technique enables the efficient acquisition of reliable results without the need for lipid extraction.

Keywords: Oxidation index, lipid index, retrieval study, oxidative degradation, lipid index subtracted oxidation index (s-OI)

DOI: 10.3233/BME-201084

Journal: Bio-Medical Materials and Engineering, vol. 31, no. 2, pp. 119-129, 2020