Efficacy of hydrated phospholipid polymer interfaces between all‐polymer bearings for total hip arthroplasty

Abstract

Measurements of wear resistance and metal ion release are important for designing bearing couples or interfaces in total hip arthroplasty (THA). In this study, we investigated wear resistance and metal ion release of surface-modified metal-free all-polymer hip bearings, such as poly(ether-ether-ketone), (PEEK) on cross-linked polyethylene (PEEK-on-CLPE), with a hydrated gel-like surface layer, to propose an improved alternative to the conventional materials used to design THA bearings. The PEEK surface resulted in less metal ion release than the cobalt-chromiummolybdenum (Co-Cr-Mo) alloy surface owing to the lack of metal. The PEEK-on-CLPE bearing (6.33 mg/10 6 cycles) had lower wear (rate) than the bearing with Co-Cr-Mo alloy-on-CLPE (10.47 mg/10 6 cycles) under controlled laboratory conditions; the wear performance of the all-polymer hip bearings was further improved with hemi-or both-surface modified with a hydrated poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC) layer (3.74 and 3.06 mg/10 6 cycles, respectively). The PMPC-grafted interface of PEEK-on-CLPE will be especially suitable for THA candidates. This study is of key importance for the design of lifelong THA and a better understanding of the limitations resulting from using PEEK. Further studies are necessary to evaluate the possibility of using this material in artificial hips.

Preparation and biotribological properties of PSBMA polyelectrolyte brush on PEEK surface

“…The minimum value and the maximum value of wear rate were 2.0713 × 10 −4 mm 3 N −1 m −1 and 1.8933 × 10 −3 mm 3 N −1 m −1 , respectively, which had an 89.06% reduction. Surface‐grafted PEEK has a lower wear rate, which is similar to Masayuki Kyomoto's report 29,55 . The variation in wear rate has a similar trend as the friction coefficient.…”

“…Figure 9 illustrated its lubrication mechanism in the SBF solution. There was no effective lubrication film formed in the lubricating medium due to the poor hydrophilicity of PEEK, whose substrate was almost directly contacted with the ZrO 2 friction pair, 55 as shown in Figure 9a, resulting in serious wear. SBMA is the zwitterionic monomer whose charge can adsorb water molecules by strong hydration and form a hydration layer in the SBF solution.…”

“…Surface-grafted PEEK has a lower wear rate, which is similar to Masayuki Kyomoto's report. 29,55 The variation in wear rate has a similar trend as the friction coefficient. With the increase of the thickness of the polymerization layer, the polyelectrolyte chain continued to extend outwards in the solution, and the simultaneous existence of amphoteric charges kept the internal extension of the molecular chain by the inter-charge repulsion.…”