Arthroscopic Debridement for Grade III and IV Chondromalacia of the Knee in Patients Older Than 60 Years - van den Bekerom, Michel P.J.; Patt, Thomas W.; Rutten, Sjoerd; Raven, Eric E.J.; van de Vis, Harm M.V.; Albers, G. H. Rob (The Journal of Knee Surgery, 2007)