The risk of infection after primary Total Hip Arthroplasties (THA)is generally estimated to be less than 1% but remains a severe and costly complication, source of morbidity and even mortality. The "biofilm" forms very early after the bacterial contamination of the prosthesis and poses a number of clinical challenges due to his resistance to immune defence mechanisms and antibiotics. Preventive strategies are needed. The poly sodium styrene sulfonate (pNaSS) is a bioactive polymer. In vitro and in vivo studies showed that poly sodium styrene sulfonate grafted on titane surfaces reduce significantly the bacterial adhesion. They also proved his biocompatibility and osseous-integration.