The emergence of various therapeutic possibilities in the field of osteoarthritis has strongly prompted clinicians to conduct studies to evaluate the symptomatic as well as the potential chondromodulating effects of these treatments. For this purpose, some authors recently proposed guidelines with regard not only to the potential outcome variables to assess cartilage breakdown but also the characteristics of both the patients and the osteoarthritis in demonstrating chondromodulating effects. The most clinically relevant variable will be chosen (with regard to simplicity as well as reliability, validity, and responsiveness). This variable will be applied in the particular subgroup of patients who show predictive factors of osteoarthritis progression.