Nickel-free high-nitrogen austenitic steel outperforms CoCrMo alloy regarding tribocorrosion in simulated inflammatory synovial fluids.

Radice, Simona; Neto, Mozart Q; Fischer, Alfons; Wimmer, Markus A · J Orthop Res · 2022

biomechanical · Level V

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Abstract

CoCrMo alloys are well-established biomaterials used for orthopedic joint replacement implants. However, such alloys have been associated with clinical problems related to wear and corrosion. A new generation of austenitic high-nitrogen steels (AHNSs) has been developed for biomedical applications. Here, we have addressed influences of hyaluronic acid, combined with inflammatory (oxidizing) conditions, on tribocorrosion of the high-nitrogen FeCrMnMoN<sub>0.9</sub> steel (DIN/EN X13CrMnMoN18-14-3, 1.4452), and of the low carbon CoCrMo<sub>0.03</sub> alloy (ISO 5832-12). We aimed to elucidate critical and clinically relevant conditions affecting the implant's performance in certain orthopedic applications. Tribocorrosion tests were conducted in triplicate, with discs under reciprocating sliding wear against a ceramic ball. Different lubricants were prepared from standardized bovine serum solution (ISO 14242-1), with variable additions of hyaluronic acid (HA) and hydrogen peroxide (H<sub>2</sub> O<sub>2</sub> ). Test conditions were: 37°C, 86,400 cycles, 37 N load (20-40 MPa after run-in phase). Volumetric wear was quantified; surfaces were evaluated by electrochemical parameters and microscopy/spectroscopy analyses (SEM/EDS). Factorial analysis of variance tests was conducted to examine the effects of HA, H<sub>2</sub> O<sub>2</sub> , and test material on wear- and corrosion-related dependent variables. Tribocorrosion performances of CoCrMo<sub>0.03</sub> and FeCrMnMoN<sub>0.9</sub> were comparable in fluids without H<sub>2</sub> O<sub>2</sub> . With higher H<sub>2</sub> O<sub>2</sub> concentrations, tribocorrosion increased for CoCrMo<sub>0.03</sub> , while this was not the case for FeCrMnMoN<sub>0.9</sub> . HA significantly enhanced wear of CoCrMo<sub>0.03</sub> in the absence of H<sub>2</sub> O<sub>2</sub> , while it mitigated the tribocorrosive action of 3 mM H<sub>2</sub> O<sub>2</sub> ; HA had no impact on FeCrMnMoN<sub>0.9</sub> . These results indicate a favorable performance of FeCrMnMoN<sub>0.9</sub> compared to CoCrMo<sub>0.03</sub> , and encourage further research on AHNS for certain orthopedic applications.

Medical subject headings