The utility of synovial fluid levels of ADAMTS9 and ADAMTS4 in predicting treatment responses to intraarticular steroid injections in patients with knee osteoarthritis

Background/aim: This study aims to identify the role of synovial fluid levels of a disintegrin and metalloproteinase with thrombospondin motifs 9 (ADAMTS9) and a disintegrin and metalloproteinase with thrombospondin motifs 4 (ADAMTS4) for the prediction of intraarticular steroid injection success in knee osteoarthritis (OA).

Material and methods: A total of eighty-four advanced stage knee OA patients (42 with stage 3 OA and 42 with stage 4 OA) were enrolled in the study. Baseline and posttreatment outcomes were determined using Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC). Pretreatment synovial fluid ADAMTS9 and ADAMTS4 levels were measured by enzyme linked immunosorbent assay (ELISA). ‘’Total WOMAC score regression of 18% and above’’ was taken as a minimal clinically important difference (MCID) to indicate improvement. Determining the best predictors of intraarticular steroid injection success in both groups was evaluated by multiple logistic regression analyses.

Results: Synovial fluid ADAMTS9 levels were significantly lower in the stage 4 OA group when compared with the stage 3 group. The level of synovial fluid ADAMTS9 was statistically significantly lower in the WOMAC score percent change ≥18% than the WOMAC score percent change <18% group in Stage 3 OA group (P = 0.026). Decreasing synovial fluid ADAMTS9 levels (odds ratio (OR): 0.625, 95% confidence interval (CI): 0.437–0.893) were found to be predictive for the WOMAC score percent change ≥18 in all OA patients (P = 0.010). Decreasing ADAMTS9 levels in synovial fluid (OR: 0.602; 95% CI = 0.372–0.974) were predictive for MCID in stage 3 OA patients (P = 0.039).

Conclusion: The lower levels of ADAMTS9 in synovial fluid may be used in conjunction with high WOMAC scores in the prediction of intraarticular steroid injection success and advanced stage knee OA patients.