Several soluble biomarkers have been identified as potential candidates to predict or monitor the efficacy of intervention. Coll2-1, a degradation product of type II collagen, and Coll2-1NO2, a nitrated form of the Coll2-1 peptide have been studied in human osteoarthritis and entered the qualification process. Evidences demonstrated them to be pertinent and to be foresee as markers used for the diagnosis, the prognosis, the burden of disease and the monitoring of a treatment efficacy.