Inclusion Criteria:  If woman, not to be pregnant Have radiographically diagnosed osteoarthritis of the knee that meets OARSI criteria for gonarthrosis (Altman and Gold, 2007; Kellgren and Lawrence, 1957). Present a Kellgren-Lawrence radiographic score lower than 4 Be treated with visco-supplementation after failure of conventional analgesic treatments and non-pharmacological modalities.  Exclusion Criteria:  BMI greater than 28 BMI lower than 15 Kellgren-Lawrence score of 4 Patients with no clinical symptoms of osteoarthritis Patients treated with intra-articular steroid injection during follow-up Patients who have had a synovectomy Patients with severe systemic disease or with rheumatoid arthritis or other intercurrent rheumatic disease