In vitro study of a new surface modified biodegradable metallic material for orthopaedic implantation

Abstract

INTRODUCTION: Some orthopaedics metallic implants require removal after healing so as to avoid stress shielding effect. The use of degradable metals such as magnesium-based alloys is therefore an alternative. However, rapid degradation and hydrogen gas release are the major obstacles. Surface modification can effectively tackle the problem of rapid degradation. Surface treatment using a novel substance, termed substance 'X' has been recently applied by our team to enhance the corrosion resistance of AZ91 magnesium alloy. This study aims to investigate the corrosion resistance and biocompatibility of the untreated and treated alloys. METHODOLOGY: Immersion test using simulated body fluid for 14 days with the temperature controlled at 37°C was appl ied to simulate an in vitro corrosion environment. The concentration of the released ions was analysed by inductively-coupled plasma mass spectrometry. To evaluate cell attachment and proliferation, the treated and untreated samples were cultured for 1 and 3 days using green fluorescent protein mouse osteoblasts. RESULTS AND DISCUSSION: The Mg ions released by untreated sample are 9,920ppm which is about 14 folds higher than the treated at day 14. Gas bubble formation is not found on the treated sample at day 14, whereas severe corrosion and gas bubble formation are observed on the untreated one. It seems the treatment can successfully suppress the rapid degradation. In cell culturing, osteoblasts are well tolerated with the treated samples. However, no cell is found on the untreated surface. The next step is to observe in vivo degradation using animal model.