Lipid index to quantify the absorbed lipids in retrieved UHMWPE components of joint arthroplasty

Article type: Research Article

Authors: Sakoda, Hideyuki^a; | Tsuboko, Yusuke^a | Okamoto, Yoshihiro^a | Yamamoto, Eiichi^a | Imagama, Takashi^b | Sakai, Takashi^b | Hamada, Hidetoshi^c | Sugano, Nobuhiko^d

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

Correspondence: [*] Corresponding author: Hideyuki Sakoda, Division of Medical Devices, National Institute of Health Sciences, 3-25-26 Tonomachi, Kawasaki, Kanagawa 210-9501, Japan. Tel.: +81 44 270 6544; Fax: +81 44 270 6545; E-mail: sakoda@nihs.go.jp

Abstract: BACKGROUND:The ultra-high molecular weight polyethylene (UHMWPE) component of artificial joints is one of the most important factors affecting the clinical outcomes of joint arthroplasty. Although the possibility of in vivo UHMWPE degradation caused by absorbed lipids has been reported, a quantitative evaluation of this phenomenon has not yet been performed. OBJECTIVE:This study aimed to establish the lipid index (LI) as a quantitative indicator of the amount of absorbed lipids and the first step to quantify their effects on UHMWPE. METHODS:The LI was defined using the infrared spectrum obtained with a Fourier-transform infrared spectrophotometer and verified using the retrieved UHMWPE components. RESULTS:The LI was consistent with the amount of extract recovered in reflux extraction with hexane. In addition, the LI could replace lipid extraction for calculating the oxidation index (OI) because the value obtained by subtracting the LI from the OI showed good agreement with the OI obtained after lipid extraction. CONCLUSION:The LI represents the amount of lipids absorbed by UHMWPE and is useful for quantitatively evaluating the effects of lipids on UHMWPE. In addition, the LI enables OI measurements that are unaffected by absorbed lipids without requiring troublesome lipid-extraction procedures.

Keywords: Peak separation, FTIR, retrieval study, UHMWPE component, oxidation index

DOI: 10.3233/BME-230183

Journal: Bio-Medical Materials and Engineering, vol. 35, no. 3, pp. 293-302, 2024