Synovial cytokine expression in ankle osteoarthritis depends on age and stage

Aim of the study was the analysis of cytokine expression in ankle osteoarthritis (OA) hypothesizing age-dependent regulation patterns.

Forty-nine patients undergoing an arthroscopy of the ankle with different stages of chronic OA were prospectively included in a clinical trial comparing the group <18 years (n = 9, Ø15.1 ± 2.0 years) with the older patients (≥18 years, n = 40, Ø36.5 ± 11.9). Lavage fluids were analysed by ELISA for levels of aggrecan, BMP-2/7, IGF-1/R, bFGF, CD105, MMP-13, and IL-1β. Additionally, clinical parameters and scores (FFI, CFSS, AOFAS) were evaluated and supplemented by radiographic scores [Kellgren-Lawrence Score (KLS) for conventional X-rays, Ankle Osteoarthritis Scoring System (AOSS) for MRI].

In contrast to distribution of gender and BMI (p < 0.005), parameters characterizing the cartilage defect as ICRS grading, size, and duration of symptoms were not dependent on age. The incidence of osteochondritis dissecans (OCD) was higher in the group <18 years (p < 0.006), but the average degree of OCD grading was not different. KLS and AOSS were significantly higher in the group ≥18 years (p < 0.02). Correlating with the higher degree of OA in the elderly, clinical function measured by FFI and AOFAS was statistically significantly worse (p < 0.05). Intra-articular concentrations of aggrecan (3.1-fold), bFGF (8.7-fold), BMP-7 (2.7-fold), and CD105 (1.5-fold) were statistically significantly higher in the group ≥18 years (p < 0.03).

Confirming the hypothesis, increased synovial levels of aggrecan, bFGF, BMP-7, and CD105 were found in patients over 18 years. This correlated with a higher stage of OA determined by radiographic changes or deteriorated function and may offer starting points for new diagnostics and interventional strategies.

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