The value of preoperative knee aspiration and arthroscopic biopsy in revision total knee arthroplasty

Aim: The accurate preoperative diagnosis of occult sepsis in endoprosthetic loosening of total knee arthroplasty is the key to successful management of revision total knee arthroplasties. The aim of this study was to evaluate the results of preoperative aspiration in comparison with preoperative arthroscopic biopsy of the synovial tissue. Method: From 2000 to 2004 eighty-six revision total knee arthroplasties in 86 patients were performed. 60 patients had only a knee aspiration, 15 an arthroscopic biopsy and an aspiration, 11 only arthroscopic biopsy. The results of both methods were compared with the intraoperative cultures during revision surgery. Results: 69 aseptic and 17 septic knee exchange arthroplasties were performed. The preoperative aspiration of the prosthetic knee joint had a sensitivity of 68.8%, specificity of 96.6%, positive predictive value of 84.5% and a negative predictive value of 92.2%. The preoperative arthroscopic biopsy had a sensitivity of 100%, specificity of 94.7%, positive predictive value of 87.4% and a negative predictive value of 100%. Conclusion: Preoperative aspiration of the knee is a very helpful study for the diagnosis or exclusion of infection in a prosthetic knee joint and should be a standard procedure in the diagnosis of prosthetic loosening. If after aspiration a suspicion of infection remains, then the biopsy is an accurate procedure to diagnose or exclude periprosthetic sepsis.