Recently, the determination of biochemical markers has been intensely explored to better understand the mechanisms underlying knee OA. In this study, we aimed to explore the expression pattern of five biochemical markers in patients with knee OA.
After IRB approval and signed informed consent, 26 patients were enrolled. Serum and synovial samples were collected prior to knee arthroscopy. Pre-operative assessment included diagnosis, Lysholm, Tegner Activity Scale, IKDC score, and radiographic Kellgren and Lawrence classification. ELISA of CTX-I, CTX-II, NTX-I, MMP3, and MMP13 were measured in serum and synovial fluid samples.
Twenty-six patients were included, with a mean age of 42 ± 15 years old. Mean results and standard deviation of the biomarkers in serum were as follows: CTX-I 5.8 ± 5.5 ng/mL, CTX-II 3.8 ± 1.7 ng/mL, NTX-I 52 ± 71 (nM BCE), MMP3 1.18 ± 0.6 ng/mL, and MMP13 1243.6 ± 1422 pg/mL; synovial fluid results were as follows: CTX-I 0.74 ± 0.5 ng/mL, CTX-II 5.1 ± 2.5 ng/mL, NTX-I 254 ± 85 (nM BCE), MMP3 0.4 ± 0.4 ng/mL, and MMP13 797 ± 1391 pg/mL. We observed a differential pattern of expression in serum NTX-I in patients with chronic meniscus injuries when compared with ACL injuries or cartilage lesions.
In conclusion, the clinical criteria of early OA are useful to categorize patients with knee conditions. The biochemical markers explored did not yield a differential pattern that can be associated with this classification. Serum NTX-I could be a useful marker of chronic meniscal lesion in future longitudinal studies, after adjusting for age and sex.