Intraarticular gold for knee osteoarthritis: An ancillary analysis of biomarkers and outcome of a pilot study.

Objective: In a previous pilot study, we have shown that intraarticular gold micro-particles can reduce knee osteoarthritis (KOA) pain at two years follow-up. Proteomic changes in serum and synovial fluid within eight weeks were associated with multiple inflammatory and immunological processes. The relation between the different biomarkers and the outcome measures is not known. We hypothesized that improvement in pain and function were associated with specific groups of biomarkers. We present the integrative analyses between proteomic biomarkers and outcomes. Design: A cohort of 30 patients, with moderate KOA, were included. Using the patients' synovial fluid as the carrier, 20 ​mg gold microparticles were injected intraarticularly. Clinical outcome measures at inclusion, 8 weeks, and 2 years, were the PainDetect questionnaire, WOMAC pain, stiffness, and function. In addition, Quantitative Sensory Testing, Pain Pressure Threshold, Temporal Summation, Conditioned Pain Modulation, and pain diary were assessed at inclusion and after 8 weeks. Proteomic analysis was performed on SF and blood samples before and after 8 weeks of treatment. Results: Linear combinations of serum or synovial biomarkers changed significantly alongside the effect measures and PainDetect scores following gold micro-particle treatment. Of particular interest was identifying multiple members of a molecular complex that is suggestive of neural tissue regeneration and modulation following gold micro-particle treatment. Conclusions: Gold microparticles are a possible future option for the treatment of knee osteoarthritis. The treatment triggers putative regenerative and inflammation-modulating molecular mechanisms.