Knee osteoarthritis is a major cause of physical disability worldwide; in fact, because there is no cure. With the purpose of reversing the degenerative process that osteoarthritis causes, and therefore, heal it; the criteria to diagnose early-stage osteoarthritis has been suggested, so patients at risk of developing it and responders to certain treatments will be identified. For these profile patients, in which high-intensity athletes are included, intraarticular hyaluronic acid and platelet-rich plasma injections may offer the possibility to reverse, or at least, halt osteoarthritis degenerationObjective The purpose of the project is to determine whether reverse progression of osteoarthritis, or at least, cessation of further degeneration is possible by using minimally invasive procedures, including HA and PRP intraarticular injectionsDesign A triple-blinded, randomized, placebo-controlled clinical trial. Designed as multicenter, based at the hospital Santa Caterina in SaltParticipants Young high-intensity athletes diagnosed with early osteoarthritis by Criteria for early osteoarthritis of the Articular Cartilage Committee of ESSKA