Abstract
Introduction:
The diagnosis of implant-associated infections is challenging, and the conventional culturing of periprosthetic tissue has been the gold standard for diagnosis of implant-associated infections. However, conventional diagnostic tests are inaccurate because the pathogenesis of implant-associated infection is related to microorganisms growing in biofilms. We compared culture of samples obtained by sonication of explanted implants to dislodge adherent bacteria from implants with conventional culture of periprosthetic tissue. The purpose of this study is to evaluate the results of sonication that is microbiological diagnostic method for implant-associated infections.
Materials and Methods:
Between January 2013 and April 2013, a total of 19 consecutive patients underwent the removal of implants at our institution. There were 15 women and 4 men with a mean age of 71 years (32 to 90) at the time of the operation. Implants were removed because of aseptic loosening in 9 patients, infection in 6 patients, necrosis in 2 patients, dislocation in 1 patient and implant fracture in 1 patient. Removed implants, including 17 joint prostheses and 2 fracture fixation devices, were subjected to sonication in a BactoSonic (BANDELIN, Germany). Preoperative bacterial culture, intraoperative conventional culture of periprosthetic tissue, intraoperative culture of sonicate-fluid, and pathological examination were assessed.
Results:
Of the 9 patients with aseptic loosening, 1 patient was positive for intraoperative conventional culture of periprosthetic tissue, and 2 patients were positive for intraoperative culture of sonicate-fluid. In the patient with negative culture of periprosthetic tissue and positive culture of sonicate-fluid, pathological findings indicated the presence of neutrophils in tissue specimen. Of the 6 patients with infection, 4 patients were positive for intraoperative conventional culture of periprosthetic tissue, and 3 patients were positive for intraoperative culture of sonicate-fluid. Of the 4 patients with necrosis, dislocation, and implant fracture, no patients were positive for intraoperative conventional culture of periprosthetic tissue or intraoperative culture of sonicate-fluid.
Conclusion:
Culture of sonicate-fluid has been shown to improve the diagnosis of implant-associated infections. In the future, it may be common technique for diagnosis of implant-associated infections associated with biofilm, but this new technique needs further study.
