Detectable levels of pyridinoline are present in synovial fluid from various patients with knee effusion: preliminary results.

There is a major interest for using biochemical markers of bone metabolism as a non-invasive tool for diagnostic purposes in the field of bone and joint diseases. Based upon the fact that the pyridinium cross-links of collagen are markers of bone and cartilage degradation, this study was designed to assess the presence of pyridinoline in synovial fluid samples originating from various arthritic and non-arthritic knee joints. Using a sample pooling method, significant levels of pyridinoline could be measured in synovial fluid by high performance liquid chromatography. Pyridinoline levels ranged from 19.3 +/- 5.8 pmol mL-1 (mean +/- SD) in osteoarthritic knee joints up to 32.4 +/- 14.6 pmol mL-1 in rheumatoid arthritis joints. Pyridinoline levels in synovial fluid were not significantly correlated to disease duration and synovial fluid cell count, but were correlated to erythrocyte sedimentation rate in osteoarthritic patients (r = 0.99, P = 0.002). This study demonstrates that synovial fluid originating from knee effusion contains significant levels of pyridinoline which can be quantified by high performance liquid chromatography and could, therefore, be a tool to investigate the metabolism of a single joint.