A multi-centre, open label, long-term follow-up study to evaluate the benefits of a new viscoelastic hydrogel (Hymovis®) in the treatment of knee osteoarthritis.

To evaluate the long-term efficacy and safety of Hymovis® in the symptomatic treatment of knee osteoarthritis (OA).This is a prospective, multi-center, open label, phase III clinical study. Two intra-articular injections (3 mL) of Hymovis® (8 mg/mL HYADD® 4) were administered 1 week apart at the beginning of the study on day 0 and day 7 and after 6 months from baseline, on day 182 and 189. Follow-up assessment were conducted for 52 weeks. 50 subjects, > 40 years old, with knee OA, with clinical and radiological confirm, complain pain in the target knee were enrolled. The variables considered were: WOMAC questionnaire, Joint Space Width (JSW), OMERACT OARSI responder criteria, EQ-5D questionnaire, rescue medication consumption.After the injections of Hymovis®, pain perceived by the patient when walking on a flat surface (WOMAC A1 score) significantly improves at the end of the study respect to the baseline. WOMAC stiffness, physical function and total score significantly improve during the study since 3 months after treatment, and it is maintained up to the end of the study (p < 0.001). By the x-ray analysis of knee, a radiological progression of OA was observed in the 26% of patients at the end of the study, while 88% of patients result to be responder to the therapy classified as per OMERACT-OARSI criteria. The EQ-5D weighted index increased significantly, against baseline, at each study time point (p < 0.001). Investigator's and patient's global assessment of the disease measured by the VAS both show a marked improvement in patient's health conditions.Results from this study confirm that Hymovis® alleviate the knee pain since the first treatment cycle. The patients treated with two cycles of intra-articular injections of Hymovis® have a progressive pain reduction that is maintained up to one year after the treatment start with improve of all the scores considered in this study. Hymovis® is effective and safe in symptomatic treatment of painful knee OA.