[Polymerase chain reaction in diagnosis of infection of total knee replacement.]

Polymerase chain reaction allows a direct detection of DNA of bacterial pathogens in synovial fluid. With the help of artificially synthetized nucleotides, the so called primers, and in the presence of DNA polymerase enzyme it is possible to produce a great number of copies of the DNA being investigated and subsequently detect them. Authors used this method in 32 symptomatic knees after TKR (P.F.C. cemented type - Johnson and Johnson). Group I (pyogenic infection) comprised 14 patients. Their clinical condition required operation - extraction of TKR, debridement, spacer, lavage. All of them were PCR positive. Only 6 patients had a positive bacteriological cultivation, 8 of them were bacteriologically negative. Group II (synovialitis) included 18 patients. All of them had a negative bacteriological cultivation. Group II.a showed a slightly positive PCR reaction (mitigated infection, detection of DNA microbes incapable of reproduction). After the treatment by antibiotics the patients were without complaints. Group IIb included patients who were all PCR negative. Their case was non-bacterial irritation of synovial membrane. They had a good response to non-steroid antiflogistics. The sensitivity of PCR method is 100%, it can detect also microbes in patients treated by antibiotics. PCR method is fast providing results within 24 hours. It reliably detects the presence of bacteria in the punctate, it specifies diagnosis and contributes to the distinguishing between pyogenic infection from non-bacterial synovialitis. Key words: total knee replacement, infection.