Background: The study was conducted to: 1) demonstrate the effectiveness of a treatment protocol with Ozone therapy in pain, function, and quality of life in patients with knee osteoarthritis; and 2) apply Ozone as a conservative treatment option with a demonstrable level of scientific evidence. Methods: This prospective quasi-experimental before-after study was conducted on 119 patients with knee osteoarthritis, having Kellgren-Lawrence grade 2 or more, who were referred to hospital of Santa Cristina's University, from January 2012 to April 2016. The protocol consisted of an intra-articular infiltration of a medical mixture of Oxygen-Ozone (95%-5%) 20mL, at a 20ug / mL concentration, during a total number of 4 sessions (once per week). Pain and quality of life were measured by visual analogical scale (VAS) and Western Ontarion and Mc Master Universities Index for osteoarthritis (WOMAC) at the beginning and end of the treatment. Results: The mean age of participants was 66.29 years. The sample was composed of 70.5% Women (n = 84) and 29.5% men (n = 35). The severity of OA according to Kellgren-Lawrence scale was 2.94°. Post-puncture erythema was 8.4% (n = 10). Pain measured by VAS significantly decreased (P < 0.0001) from the score 7.89 to 2.1. The scores of WOMAC-pain, WOMAC-stiffness, and WOMAC-function subscales decreased significantly (P < 0.0001) from 15.9 to 4.4, 3.5 to 0.9, and 49.5 to 17.6, respectively. The WOMAC total score decreased from 68.9 to 22.9 (P < 0.0001). Conclusions: Ozone is a safe medical treatment that can improve significantly pain relief, stiffness, and function in patients with knee osteoarthritis. The study shows a good level of evidence as well as a good grade of recommendation that allows us to consider Ozone as a conservative therapeutic option in the treatment of osteoarthritis of the knee.

el papel del ácido hialurónico, el plasma rico en plaquetas (PRP) y el ozono en la modulación de la inflamación: una revisión. / A new paradigm for the treatment of knee osteoarthritis: the role of hyaluronic acid, platelet rich plasma (PRP) and ozone in modulating inflammation: a review.