Kon E, Di Matteo B, Delgado D, Cole BJ, Dorotei A, Dragoo JL, Filardo G, Fortier LA, Giuffrida A, Jo CH, Magalon J, Malanga GA, Mishra A, Nakamura N, Rodeo SA, Sampson S, S?nchez M. Platelet-rich plasma for the treatment of knee osteoarthritis: an expert opinion and proposal for a novel classification and coding system. Expert Opin Biol Ther. 2020 12; 20(12):1447-1460.