Pending Failure in Hard-hard Total Hip Arthroplasty

During last 6 years approximately 10.000 ceramic balls and 5.000 ceramic liners have been implanted in the region Emilia-Romagna in Italy (4 million Every single year approximately 60.000 hip prostheses are implanted in Italy. Quality of life of patients after surgery is very good, as widely demonstrated in the literature. On the basis of data produced by the only complete hip register in Italy that is run in our Lab (RIPO, Register of Orthopedic Implants in the Region Emilia-Romagna) survival rate of primary total hip prosthesis is 95.6% at 9 years. Reasons for revision are mainly aseptic loosening of one or both components (40% of the total) and dislocation (26%), being the latter much more frequent in the first two years. Less frequently revision is due to sepsis (7% of the total),bone fracture (11%), prosthesis fracture (3%) or pain (3%). Revision is relates, among the others, to prosthesis-related factors, such as fixation to bone and articular coupling. In our experience, during the last ten years 32% of implants had both articular component in ceramic , 34% had metal head and plastic liner, 24% ceramic head and plastic liner, 10% both components in metal. Each solution has strengths and weakness and they have been identified and clinically applied in order to overcome step by step limitations observed in the previous one. The most recent are the hard-on-hard bearings, that is ceramic on ceramic and metal on metal. These two solutions, beside very promising results on wear resistance, show some peculiar failures: respectively fracture of the ceramic component and hypersensitivity induced by metal ions. Aim of research proposal is to investigate two uncommon and less investigated early symptoms of failure: * 'noising hip' in ceramic on ceramic total hip arthroplasty * pain without radiographic signs of loosening in metal on metal total hip arthroplasty These two situations are extremely relevant, as they prelude to a failure of the prosthesis. If clearly ide