A Multicentre Clinical Investigation to Assess Efficacy and Safety of Intra-articular Injections of Hyaluronic Acid Combined With Chondroitin Sulfate in Knee Osteoarthritis

Inclusion Criteria: * At Screening * Male or female between the ages of 40 and 80 * Body Mass Index (BMI) ≤ 30; * Mean knee pain score at rest over the last 24 hours evaluated on VAS (0-100) ≥ 40. The most painful knee is considered the target knee; * OA of the Knee radiologically and clinically confirmed responding to criteria of American College of Rheumatology (ACR): pain of the knee and crepitus on active motion or morning stiffness less than 30 minutes or age \>50 years * Symptomatic knee pain for more than 6 months; * Radiological Kellgren and Lawrence grade II or III confirmed by an X-ray not older than 12 months; * Willing to discontinue any systemic analgesic/NSAID therapy, opioids, systemic corticosteroids, skeletal muscle relaxants, and any other medication that would interfere with the study assessments, except for the rescue medication, with no intention to resume them during the clinical investigation (see Appendix 5 for wash out period); * Patient able to comply with the instructions of the clinical investigation and to maintain a Rescue Medication Diary during the study; * Having signed the study informed consent. * at Baseline * Patient does not have chondromatosis or villonodular synovitis of the knee evaluated by Ultrasound; * Patient has complied with the requirements for rescue medication (no more than 6 tablets or 3 grams of paracetamol per day up to 4 days per week and paracetamol discontinued 24 hours before first IA injection); * Mean knee pain score at rest over the last 24 hours evaluated on VAS (0 - 100) ≥ 40 (with a washout period for Paracetamol of 24 hours); * Patient has discontinued prior to Baseline the use of all prohibited medications in accordance with the washout period defined in Appendix 5; * Patient continues to meet all Screening inclusion/exclusion criteria at the Baseline visit. Exclusion Criteria: * Related to the OA pathology * Recent trauma (\< 1 month) of the target knee responsible for the symptomatic knee pain; * Articular disease resulting from articular dysplasia, aseptic osteonecrosis, acromegaly, Paget's disease, haemophilia, hemochromatosis; * Inflammatory or autoimmune diseases (e.g., rheumatoid arthritis, gout and infectious arthritis, acute calcium pyrophosphate arthritis); * Pathologies interfering with the evaluation of OA. Related to treatments * Corticosteroids injection in the target knee in the last 3 months before first intra-articular (IA) injection; * Hyaluronan injection in the target knee in the last 6 months before first IA injection; * Arthroscopy and surgery in the target knee in the last 3 months before first IA injection; * Oral corticosteroid therapy ≥ 5mg/day (in Prednisone equivalent) in the last 3 months before first IA injection; * OA treatments based on curcuma extract in the last 3 months before first IA injection; * Change in the dosage of symptomatic slow-acting drugs (SYSADOA) e.g., chondroitin, glucosamine, diacerein or avocado-soya unsaponifiables in the last 3 months before first IA injection; * Contraindications to 4% GAG: hypersensitivity to the product components; * Infections or skin diseases in the area of the injection site; * Change in the dosage of ongoing non-pharmacologic therapy for the lower extremities (including physical therapy) initiated in the month before first injection; * Anticoagulant (coumarinic compound) and heparin. Related to associated diseases * Severe diseases (e.g., liver or renal failure, lung/heart disease, tumour, HIV); * Severe alteration of mobility interfering with the functional evaluation; * High risk of haemorrhage; * Patient with known allergy to paracetamol; * Anticipated need for any surgical or other invasive procedure during the trial including prosthesis in the target knee. Related to study subjects * Participation to a therapeutic clinical trial in the last 3 months before first injection; * Pregnancy, breastfeeding, planned conception and premenopausal women without contraception, tubal ligation or hysterectomy