Efficacy and Safety of a Intra-articular Injection, ENKO1, in Patients With Symptomatic Knee Osteoarthritis.

Inclusion Criteria: * Medial femorotibial compartment knee OA. * Fulfilment of ACR criteria for knee OA (knee pain + grinding + stiffness in the morning \< 30 minutes). * Patients with a clinical course of disease longer than 6 months. * Global pain score greater than 60 mm on a 0-100 mm VAS on the knee under study. * Grade II or III according to the Kellgren and Lawrence classification system for the knee under study (on a posteroanterior X-ray performed under weight-bearing and for 6 months before randomisation). * Patients taking analgesics for at least 3 months before randomisation and whom are dissatisfied with their current therapy. * Patients who have given their consent in writing to take part in the study. * Woman of childbearing age must take a urine pregnancy test which must be negative at the randomisation visit and be currently using an effective contraceptive method for at least 2 menstrual cycles (oral contraceptives, intrauterine device, tubal ligation or other effective procedures). Exclusion Criteria: * Isolated symptomatic patellofemoral osteoarthritis. * Microcrystalline osteoarthritis. * Prosthesis in knee under study. * Joint lavage or arthroscopy or any surgery on the knee under study in the 6 months before randomisation. * Paget's disease of bone, chondromatosis or villonodular sinovitis. * Inflammatory, infectious or metabolic arthritis (rheumatoid arthritis, spondyloarthropathy or connective tissue diseases). * Haemochromatosis, ochronosis or haemophilia. * History of diseases that the investigator considers likely to interfere with the functional disability assessment. * Knee surgery planned during the study period. Other disease-related criteria: * BMI greater than or equal to 30. * Immunodeficiency or a serious or progressive disease (heart, lung, liver, kidney, haematological, neoplastic or infectious disease). * Skin diseases or infections in the area of the injection site. * Previous history of venous thromboembolism (including pulmonary embolism) or high risk of venous thromboembolism. * Venous or lymphatic stasis of the leg under study. * Severe acute or chronic disease that the investigator considers incompatible with the conduct of the study. * Disease that the investigator considers likely to interfere with the study results or to expose the patient to an additional risk. * Alcohol or drug abuse or dependence. Previous or concomitant treatment-related criteria: * Patients who have taken a SYSADOA, SERM or a drug/dietary supplement containing glucosamine, chondroitin sulfate, diacerein or avocado-soybean extracts in the 3 months before randomisation * Patients who have taken paracetamol in the 24 hours before randomisation or any other symptomatic analgesic drug, including NSAIDs (except aspirin up to 325 mg/day for cardiovascular prophylaxis), in the 48 hours before randomisation * Patients who have received any corticosteroid treatment by any route of administration (other than inhalers or the ocular or auricular routes) in the month before randomisation * Patients who have received an intra-articular steroid injection in the knee under study in the month before randomisation or patients who have received intra-articular hyaluronic acid in the target knee in the 6 months before randomisation * Patients who have received any local or topical treatment on the target knee in the 2 weeks before randomisation Criteria related to concomitant medication: * Hypersensitivity to paracetamol or NSAIDs Study product-related criteria: * Known allergy to the study treatments or to any of its ingredients. Other criteria: * Patients likely to be unable to comply with the protocol instructions and/or treatment, in the investigator's opinion * Patients who have taken part in a clinical trial in the preceding 2 months or taking part in a trial at the time of randomisation * Patients linguistically or mentally incapable of understanding the nature, objectives and possible consequences of the study; or who refuse to be subject to its limitations * Patients who are family or colleagues (secretary, nurse, technician, etc.) of the investigator. * Women: pregnant or breastfeeding