title: Letter to the editor.
authors.affiliation: Support Unit in Epidemiology and Biostatistics, Department of Public Health, Epidemiology and Health Economics, University of Liège, CHU Sart Tilman, 4000 Liège, Belgium. Electronic address: olivier.bruyere@ulg.ac.be.
authors.forename: Olivier
authors.initials: O
authors.lastname: Bruyère
authors.affiliation: Support Unit in Epidemiology and Biostatistics, Department of Public Health, Epidemiology and Health Economics, University of Liège, CHU Sart Tilman, 4000 Liège, Belgium.
authors.forename: Jean-Yves
authors.initials: JY
authors.lastname: Reginster
mesh_terms: D006801:Humans; D020370:Osteoarthritis, Knee / Q000628:therapy*