An Efficacy and Safety 6-months Study of SYNOLIS VA 80/160 and SYNOLIS VA 40/80 in the Treatment of Symptomatic Knee Osteoarthritis

Inclusion Criteria: * Patient between 35 and 75 years old * Patients with knee osteoarthritis. The diagnosis is based on the following American College of Rheumatology (ACR) classification: * Knee pain * Positive radiography (presence of osteophytes) * Morning stiffness \< 30 min and/or crepitus while walking * Symptoms related to knee osteoarthritis for at least 6 months * Treatment failure (i.e. ineffective response) with analgesics and/or NSAIDs or intolerance to NSAIDs or low-grade opioids * Kellgren-Lawrence radiographic stage: I - III (pre-inclusion radiography) * WOMAC pain index score ≥ 40 mm (VAS 0-100 mm) on the knee to be treated * Contralateral knee pain \< 10 mm (VAS) compared to treated knee * Patient signed inform consent form- Exclusion Criteria: * Inability to understand the study or language used to be informed/sign the consent * Participation in another clinical trial within 4 weeks prior to the start of the trial, and commitment to non-participation within 4 weeks following the end of the trial * Intraarticular injection of hyaluronic acid in target knee within the 6 months prior to inclusion * Patient who has received an intra-articular (IA) or intra-muscular (IM) steroid injection within the 3 months prior to inclusion or has taken oral corticosteroids within the month prior to inclusion * Joint, bone, ligament, or any local or loco-regional surgery of the leg involved, arthroscopic operation on the target knee within the 3 months prior to inclusion * Any recent trauma to the leg involved, including a sprain, dislocation within the 3 months prior to inclusion * Rheumatoid arthritis, joint condition or any other inflammation and arthritis * Lupus * Dermatological disorder or any epidermal conditions that prevent an intraarticular injection * Visible joint effusion of the target knee during physical examination evidenced by a protuberance or positive ballottement of the patella * Evidence of a subchondral fracture, meniscal lesion, presence of bone or cartilage fragments, horizontal meniscal lesion tear (FLAP) in the target knee * Osteonecrosis (1 or both knees) * Daily dosage \> 101 mg of acetylsalicylic acid as part of cardiovascular preventive treatment (antithrombotic). If dose \< 101 mg, must be maintained during the study * Known intolerance/hypersensitivity/allergy to any of the components in either product, SYNOLIS VA * Fibromyalgia * Patient of childbearing potential, pregnant or breast-feeding known at inclusion or in the planning phase during the study unless willing to use contraceptives through the whole duration of the study * Excessive and repeated consumption of alcohol or illicit substances * Any medical condition that may interfere with the proper conduct of the study (including any surgery or hospitalisation)