Abstract
Aim
Low-grade infections cannot be easily distinguished from aseptic complications frequently leading to false negative diagnoses and late onset of anti-bacterial therapy. Therefore, there is a great need to establish biomarkers for early detection of low-grade infections.
Method
In this study, we focused on the investigation of anti-α-defensin, anti-C3, anti-C5 and anti-C9 as potential biomarkers for infection in a cohort of hip and knee septic revision cases, taking patient characteristics and comorbidities into account. Here we included 78 patients with septic (35) and aseptic (43) (woman:37, men:42, age 50 – 93 years) revision surgeries of hip and knee. CRP serum levels and leucocyte blood values were evaluated. Patient characteristics, including age, number of prior revision surgeries and comorbidities were recorded. Periprosthetic tissue was stained histologically with Hematoxylin/Eosin and immunohistologically with different antibodies.
Results
The CRP values were significantly increased in the septic cohort, but no changes were observed in leucocyte count. Interestingly, we found a strong increase in the terminal complement system component C9 (septic: 0.1% ± 0.2% aseptic: 0.01% ± 0.05%, p= 0.0004) in the septic periprosthetic tissue. The predictive value of α-defensin staining was not statistically significant (septic: 0.5% ± 0.7% aseptic: 0.1% ± 0.6%, p= 0.09). Analyzing the synovial fluid of aseptic and septic patients, the presence of C9 in the septic group (1.8 ± 0.4) was not significantly higher compared to the aseptic (1.9 ± 0.7) group. The next step was to investigate the specificity C9 detection using different joint related diseases such as chondrocalcinosis (CC), rheumatoid arthritis (RA) and metallosis. The median of C9 staining in the CC group (0 ± 0.0001) was significant lower than the infection group. Similar results have been observed in RA (0.0003 ± 0.2) and the metallosis group (0.0002 ± 0.01).
Conclusions
We found a strong predictive value of anti-C9 staining for tissue infection, suggesting that C9 deposition could be a novel biomarker for the identification of periprosthetic joint infections using tissue biopsies.
