P023 - Synovial Fluid Biomarker Alternatives: Can Plasma and Urine Samples Shed Light on the Post-Traumatic Intra-Articular Microenvironment?
Abstract
Purpose
The purpose of the current study was to analyze the association of plasma and urine biomarkers with synovial fluid biomarkers that have been previously shown to be indicators of the post-injury intra-articular response.
Methods and Materials
Patients undergoing primary knee arthroscopy were invited to provide synovial fluid, blood, and urine samples prior to surgery. Indications for surgery in this cohort included ACL tear, meniscus tear, recurrent patellofemoral instability, and osteochondral defects.The concentration of 10 synovial fluid biomarkers was measured. Plasma and urine biomarkers were selected based on the previously demonstrated association with inflammatory processes and cartilage degradation. Samples were analyzed using a multiplex magnetic bead immunoassay.
Results
151 patients were included in the analysis (mean age 41.43 +/- 13.50 years). 43 patients (28.5%) had combined ACL and meniscus tears, 18 patients (11.9%) had isolated ACL tears, 76 patients (50.3%) had isolated meniscus tears, and 14 patients (9.3%) had chondral lesions.
There were several moderate and strong positive correlations between synovial fluid biomarkers. The strongest associations were between VEGF and MCP-1, VEGF and MIP-1beta, VEGF and IL-6, and IL-6 and MCP-1. There were significant negative correlations between bFGF and IL-6, MCP-1, MMP-3, MIP-1β, TIMP-1, and VEGF.
There was a significant negative correlation between plasma CRP and synovial fluid RANTES (r = -0.21, p = 0.016). There was a significant positive correlation plasma CRP and synovial fluid TIMP-2 (r = 0.19, p = 0.030). However, after Bonferroni correction, there were no statistically significant correlations between synovial fluid biomarkers and biomarkers in plasma or urine for any of the intra-articular pathologies assessed.
Conclusion
This analysis demonstrated no association between the tested plasma or urine biomarkers and synovial biomarkers that have been shown to accurately reflect post-injury changes in the intra-articular space. In the post-traumatic knee, there is no substitute for synovial fluid biomarker analysis.
