Abstract
Background Periprosthetic joint infection (PPI) is one of the most common reasons for revision
in total knee arthroplasty (TKA). Percutaneous synovial biopsy is considered as a
well-established diagnostic tool in ambiguous cases of chronic pain after TKA. The
exact number of undetected low-grade infections remains unclear.
Objectives The aim of this prospective study was to compare the diagnostic accuracy of arthroscopically
guided and unguided synovial biopsy. Additionally, the prevalence of initially undetected
PPI during synovial biopsy and revision surgery was assessed.
Materials and Methods 40 patients suffering from chronic pain after TKA and the clinical suspicion of PPI
were included in the study. Synovial biopsies were collected in a standardized manner
first without and then with arthroscopic visual control. Using both techniques, six
samples were collected each (5 for microbiology, 1 for histology). 19 patients, initially
classified aseptic, underwent revision surgery later.
Results The diagnosis of PPI was made in 10.0% of unguided biopsies (4 cases, 2× microbiologically,
2× histologically), 7.5% of arthroscopic biopsies (3 cases, 3× histologically) and
12.5% (5 cases, 3× histologically, 2× microbiologically) of all cases. Only histologic
evaluation led to concordant positive findings using both techniques in two patients.
The proportion of non-representative biopsies was twice as high after unguided tissue
collection than after arthroscopic biopsy (30.0 vs. 15.0%). Microbiologic evaluation
of arthroscopically collected biopsies did not lead to the diagnosis of PPI, which
might have been essential to the selection of the appropriate antimicrobial therapy.
During revision surgery the diagnosis of PPI was made in 22.2% of cases.
Conclusions In patients suffering from chronic pain after TKA, periprosthetic low-grade infection
was diagnosed in a relevant proportion of cases. Therefore, synovial biopsies for
histological and microbiological evaluation should be collected whenever thereʼs clinical
suspicion of PPI. For histological evaluation, samples should be collected using arthroscopic
control and ideally multiple biopsies should be taken. For microbiological evaluation,
excessive joint lavage should be avoided.
Key words
periprosthetic infection - arthroscopy - total knee replacement - minimally invasive