Objectives: Microbial biofilms protect planctonic bacteria growing on the implants surfaces from detection and antibiotic treatment. To investigate the efficacy of sonication cultures in our patients with prosthetic joint infections we compared our findings with the results to those of periprosthetic tissue cultures and histology.

Methods: The sonication cultures of the explanted prosthesis were cultured according to the protocol by Trampuz et al. in the New England Journal of Medicin and using the routine method incubating the aspirated pus and periprosthetic material in brain-heart-infusion broth without sonication. To assess the most frequently affected component of the prosthesis all components were “sono-cultured” separately. The diagnosis of infection was based on the presence of bacteria or leucocytes in pus or tissue plus local signs and symptoms and/or systemic markers of inflammation (fever, leucocytosis, increased C-reactive protein)

Results: We investigated 60 patients with 40 septically and 20 aseptically explanted components of total knee (n=24), hip (n=21) tumor (n=6) and shoulder (n=2) endoprosthesis, as well as osteosynthetic material (n=6) and spinal instrumentation (n=1). The most frequently affected component of the hip prosthesis was the femoral head (100%) and the inlay (88%), of the knee prosthesis was the Patella (58%) and the tibia plateau (56%), of the tumor prosthesis were the polyethylene components (100%), of the shoulder prosthesis was the sphere and stem (each 100%), of the osteosynthesis material were the plate and screws (each 33%) and of the spine instrumentation were the rod and the screws (each 100%). From all detected pathogens in sonication cultures the most frequently were Staphylococcus aureus (25%), Staphylococcus epidermidis (22%) and Streptococci (13%). The sensitivity of sonication cultures and periprosthetic tissue cultures was 85% and 78% without preoperative antibiotic therapy compared with histological analysis of 100% sensitivity. The specificity was 89% for sonication cultures, 95% for periprosthetic tissue cultures and 100% for histological analysis.

Conclusion: Our results of separating the explanted components for sonication culture proved the detection of valid pathogens for every kind of endoprosthesis or implants and supplied further information for the focus of infection.

In animal experiments antioxidants like Resveratrol, Quercetin-dihydrate and Selen-L-Methionine cause a growth rate decrease in synovial tissue and furthermore an inhibition of pro-infiammatory factors. We investigated the effect of these antioxidants on synovial fibroblasts of Osteoarthritis (OA) patients compared to Rheumatoid Arthritis (RA) patients.

Random biopsies of synovial membrane were obtained aseptically from joints of OA and RA patients. After in vitro expansion cells were cultivated until passage three, seeded in 96 well microtiterplates and treated with 0μM, 50μM, 100μM and 200μM of Resveratrol, Quercetin-dihydrate and Selen-L-Methionin. After 24 and 48 hours incubation cell proliferation assays and apoptosis FACS analysis were performed. Additionally woundhealing assays and photographic documentation of resettlement of synovial fibroblasts was accomplished.

The results of cell proliferation assays showed a highly significant reduction as well in OA and RA cells. In OA synovial fibroblasts 200μM of Resveratrol evoked a decrease of 72,3 ±1,7% (***), 200 μM of Quercetin-dihydrate induced a reduction of 16,11 ±3% (***). 200μM of Selen-L-Methionine evoked a decrease of 27,3 ±3,8% (***). In RA cultures 200 μM of Resveratrol evoked a decrease of 77,7 ±1,8% (***), 200μM of Quercetin-dehydrate induced a reduction of 20,38 ±15,3%(**), 200μM of Seleno-L-Methionine evoked a decrease of 23,3 ±4,8%(***)(n=20). The results of photographic documentation correlated with cell experiments. Analysis with untreated and treated OA and RA synovial fibroblasts for their content of apoptotic and necrotic cells by Annexin/7AAD staining displayed only few apoptotic cells. Caspase 3, a key mediator of apoptosis, was not activated in resveratrol-treated OA and RA synovial fibroblasts.

Resveratrol, Quercetin-dihydrate and Selen-L-Methionine showed a significant growth rate decrease in OA and RA synovial fibroblasts. In OA and RA the pharmacologic treatment with these antioxidants may be a therapeutic approach. Different apoptosis assays represented only few apoptotic cells. We therefore conclude that apoptosis is not the major pathway in resveratrol-treated synovial fibroblasts.