Characterisation by PIXE–RBS of metallic contamination of tissues surrounding a metallic prosthesis on a knee

Abstract Implants used as biomaterials have to fulfill conditions of functionality, compatibility and sometimes bioactivity. There are four main families of biomaterials: metals and metal alloys, polymers, bioceramics and natural materials. Because of corrosion and friction in the human body, implants generate debris. This debris may develop toxicity, inflammation and prosthetic unsealing by osseous dissolution. Nature, size, morphology and amount of debris are the parameters influencing the tissue responses. In this paper, we characterised metallic contamination produced by knee prosthesis, composed with TiAl 6 V 4 or Co–Cr–Mo alloys, into surrounding capsular tissue by depth migration, in vivo behaviour, content, size and nature of debris by PIXE (Particle Induced X-ray Emission) method associated with RBS (Rutherford Backscattering Spectroscopy). Debris distribution in the whole articulation is very heterogeneous. Debris migrates several thousand micrometers in tissues, with a characteristic decrease. Solid metallic particles of about micrometer size are found in the most polluted samples, in both alloys TiAl 6 V 4 and Cr–Co–Mo. In the mean volume analysed by PIXE, the concentration mass ratios [Ti]/[V] and [Co]/[Cr] confirm the chemical stability of TiAl 6 V 4 debris and show the chemical evolution of Cr–Co–Mo debris. Development of a protocol to prepare thin targets permits us to correlate PIXE and histological analysis in the same zone. The fibrous tissue (collagen fibres, fibroblasts) and macrophage cells are observed with optical microscope in polluted areas. This protocol could locate other pathologies in ppm contamination range, thanks to the great sensitivity of the PIXE method.