How can one develop disease-modifying drugs in osteoarthritis?

A disease-modifying osteoarthritis drug should be able to interfere with the cartilage breakdown observed in this disease. The current question is whether development of a drug should be focused on structural parameters (eg, radiologic joint space width, magnetic resonance imaging cartilage volume, and so on), on clinical parameters such as functional impairment, or on a composite index such as the capacity of the study drug to prevent and/or to retard the requirement for total articular replacement. Another aspect of osteoarthritis trials is that several recent advances have greatly facilitated the conduct of phase I and II studies, such as biological markers of cartilage metabolism and magnetic resonance imaging parameters of cartilage breakdown.