Evaluation by PIXE method of metallic elements migration coming from prosthesis

The number of implanted prosthesis increases each year and concerns a large amount of people of different ages. It is well known that when a metallic implant is in contact with tissue, the organism reacts and a process of corrosion can start. Consequently, we can observe a production of metallic debris and wear. In order to increase the implant life and its tolerance by the patient, we are studying coating in order to limit the propagation of the released particles in the organism. Our purpose is to estimate contamination and evaluate the migration of the metallic elements. Two types of samples were analysed. In the first case, samples are taken around the prosthesis from the head to the end of the hip implant. In the second case, samples are taken near capsular tissue in order to visualize contamination versus pathology and versus the type of implant. The experiments were made on a Van de Graaff (particle accelerator) at the CERI (Centre d'Etude et de Recherche par Irradiation) at Orleans (France) and at the CENBG (Centre d'Etude Nucleaire de Bordeaux Gradignan) at Bordeaux (France). For both cases, we used a proton beam of 3 MeV with an intensity of 2 nA. At Orleans, we can estimate the contamination of a surface and if there is a gradient of concentration between the two analysed faces. At Bordeaux, we study the evolution of contamination versus the distance between sample and implant. The result of these experiments shows that the contamination is very heterogeneous according to the pathology and the localisation of the sampling. The migration can be either ionic or particular. The different elements do not migrate in the same way. (author)