Investigation of Infected Knee- and Hipendoprosthesis

Total hip and knee arthroplasty have greatly improved the quality of life for many individuals and are one of the most successful operations currently available. Although the prevalence of infection after total hip and knee arthroplasty has decreased during time the economic impact, the morbidity, and emotional trauma of prosthetic joint infection is immense and devastating to the patient and society. Infection after total hip and knee arthroplasty has been treated by various different methods. Antibiotic suppression alone, surgical debridement in combination with antibiotic therapy, and surgical revision procedures with or without removal of the prosthesis have been tried. However, the precise indications for the different surgical approaches have not been established yet. The aim of this project is to improve the diagnosis and treatment of prosthetic joint infection. This will be done in two approaches: In the first approach we will retrospectively evaluate the differences in the outcomes, microbiology, and resource utilization in the treatment of infected arthroplasty cases managed between 1995 and 2008 at the Mayo Clinic. This will involve approximately over 1000 infected arthroplasty cases. The strengths of this retrospective review includes an extremely large and consecutive cohort including an excellent follow up and data gathering from the Mayo total joint registry and has the potential to stand as a landmark study relating to the treatment of this challenging patient group. In the second approach we will prospectively evaluate new techniques for the diagnosis of infected hip and knee prosthesis. A prompt diagnosis of infection permits early treatment and has a major impact on the outcome of periprosthetic infections. Culturing of samples of periprosthetic tissue is the gold standard used for microbiologic diagnosis of infection. However, this method often lacks sensitivity and specificity and so far there is no standard single reliable test. Therefore it is necessary to develop new diagnostic approaches. Recently ultrasonication has been used to dislodge adherent bacteria from the surface of implants. Furthermore in the research setting detection of 16S-ribosomal deoxyribonucleic acid (rRNA) by polymerase chain reaction (PCR) has been used in the molecular diagnosis of prosthetic joint infection. We will evaluate these two techniques in patients undergoing revision total hip or knee arthroplasty for different aseptic and septic indications at the orthopedic department at the Mayo Clinic. The classical inflammatory markers in the serum are of limited use for the diagnosis of periprosthetic infection. Therefore new parameters are needed to identify infection and to monitor the effectiveness of therapy. Cytokines may be elevated, particularly Tumor Necrosis Factor- a (TNF-a), Interleukin(IL)-6, IL-10 and Procalcitonin. We will prospectively evaluate these new molecular approaches to the diagnosis of periprosthetic hip and knee infection. The information obtained from this study could help to improve diagnosis and therapy of periprosthetic infection.