[A randomized, single-blind, parallel, controlled clinical study on single intra-articular injection of etanercept in treatment of inflammatory knee arthritis].

Objective: To evaluate the efficacy and safety of single intra-articular etanercept injection in patients with rheumatoid arthritis (RA) and spondyloarthropathy (SpA) who had knee arthritis.

Methods: This was a randomized, single-blind, parallel, controlled clinical trial. The subjects were the RA or SpA patients with the knee arthritis without deformity, moderate or severe bone erosion and obvious joint space narrowing in radiography in the target knees, who had taken at least 6-week therapy with routine dosage of disease modifying anti-rheumatic drugs (DMARDs) before the study. The subjects were randomized in 2:1 ratio to receive either single intra-articular 25 mg etanercept injection or 2 ml compound betamethasone to the target knees joint after their synovial fluid being drawn away at baseline. They were followed up four weeks after injection. The primary end-point was the 4-week change in the modified Hospital for Special Surgery (HSS) knee score for the target knee.

Results: Forty-seven subjects in the experimental group and twenty-three subjects in the controlled group were included in the trial. The modified HSS knee score for the experimental group was baseline mean 65.6 ± 14.0, follow-up 84.3 ± 11.1 (P < 0.0001), the controlled group baseline mean 68.2 ± 11.4, follow-up 79.4 ± 15.5 (P = 0.0015). A mean (34.9 ± 38.9)% improvement on the modified HSS knee score was achieved in the experimental group, while (17.9 ± 24.5)% improvement on the modified HSS knee score was achieved in the controlled group (P = 0.0467). Adverse events were observed in eight patients (19.0%) in the experimental group and eight patients (44.4%) in the controlled group. No serious adverse event had been observed.

Conclusions: Single intra-articular 25 mg etanercept injection had a better efficacy than 2 ml compound betamethasone. It was an effective and safe therapeutic option for SpA and RA patients who had knee arthritis without obvious change in radiography.