Efficacy of OSTENIL PLUS (Hyaluronic Acid) Versus SYNVISC-ONE in Patients With Tibiofemoral Osteoarthritis

Inclusion Criteria: * Male or female aged 40-85 years; * Primary knee osteoarthritis complying with the American College or Rheumatology criteria; * Radiographically defined osteoarthritis: joint space narrowing and osteophyte in X-ray taken less than one year previously and modified Kellgren-Lawrence grade Ib-III; * Symptoms on one side only, with a mean WOMAC A of ≥40 mm. If knee osteoarthritis is bilateral, a difference for that score between the contralateral knee and the selected knee should be of at least 20 mm; * Pain present on at least 15 days in the month before inclusion; * Failure or intolerance of first line analgesics and NSAIDs; * With health insurance; * Understanding and following the study instructions; * Signed the informed consent. Exclusion Criteria: * Knee osteoarthritis that is not symptomatic or insufficiently symptomatic; * Bilateral symptomatic knee osteoarthritis of the same severity on both sides; * Post-traumatic secondary knee osteoarthritis; * Knee osteoarthritis of radiographic grade I, Ia or IV; * Exclusively patellofemoral osteoarthritis where the symptoms are principally of patellofemoral origin (Patellar syndrome); * Symptomatic homolateral coxarthrosis; * Varus or valgus deformation of the selected knee (deformation axis ≥15° in X-ray); * Inflammatory rheumatism (rheumatoid arthritis, psoriatic rheumatism, articular chondrocalcinosis, gout, Paget's disease, ankylosing spondylitis, lupus, etc.); * History of injury to the selected knee during the 6 months before inclusion; * Venous or lymphatic stenosis of the lower limb; * Femoral or sciatic nerve root pain of the lower limb to be tested; * Tendinopathy (e.g. hip periarthritis); * Treatment with intra-articular hyaluronic acid in the selected knee during the 6 months before inclusion; * Intra-articular injection of corticosteroids in the selected knee during the 2 months before inclusion; * Treatment with symptomatic slow-acting drugs for osteoarthritis and/or dietary supplements for osteoarthritis (chondroitin sulphate, diacerein, avocado and soybean unsaponifiables, oxaceprol, copper granions, glucosamine) which had been started less than 3 months previously or whose dose had been changed during the last 3 months before inclusion; * Total knee replacement of the selected knee; * Surgery of the other knee or of the hip or any other surgery scheduled during the period of the study; * History of any surgical intervention, arthroscopy, osteotomy, etc. in the year before inclusion; * Obesity: body mass index ≥30 kg/m2; * History of autoimmune disease; * Severe condition likely to interfere with the evaluation, such as neoplasia, malignant blood disease, kidney disease, liver disease or severe infection; * Very marked hydrarthrosis (requiring puncture) at the time of inclusion; * Wound or skin condition of the selected knee; * Anticoagulant treatment with heparin or warfarin (platelet antiaggregants such as ASPIRIN ≤325 mg/d, ticlopidine or clopidogrel were allowed); * Known hypersensitivity to hyaluronic acid and/or to avian proteins and/or paracetamol; * Known hypersensitivity to mannitol; * Participation in a clinical research study within the previous 3 months; * Pregnancy, breast-feeding.