The benefits of single or repetitive administration (1 to 6) can have similar result in terms of muscular strength and patients' quality of life improvement, benefiting of the advantages of polymerized polynucleotides (IRADYN) formulation.

Of all osteoarthritis' localization into human body, knee OA represents the most common OA localization.

On 2014 the European Society for Clinical and Economic Aspects of Osteoporosis and Osteoarthritis (ESCEO) has suggested as first step of pharmacological treatment for knee osteoarthritis (OA) a background therapy with chronic symptomatic slow-acting drugs for osteoarthritis (SYSADOAs). In this class of natural compounds, hyaluronic acid (HA) has evidenced its efficacy after intra-articular (IA) administration in patient with mild to moderate knee OA .

The filler used in this clinical investigation is using polymerised polynucleotides (PDRN) that has hydrophilic properties of polyanions; therefore, it can bind water molecules and provide a moisturising and lubricant effect. Its viscoelastic properties allow it to compensate for the loss of synovial fluid viscosity in the event of degenerative or trauma joint alterations. These actions reduce the mechanical stress on joints, thereby decreasing friction. This improves joint function and movement with significant relief of pain commonly associated with this problem. Moreover, the enzymatic degradation of the polynucleotide chain releases nucleotides into the synovial cavity. These nucleotides can bind water molecules and share the same viscoelastic properties as the entire chain, helping extend the duration of the effect.

The benefits of single or repetitive administration (1 to 6) can have similar result in terms of muscular strength and patients' quality of life improvement, benefiting of the advantages of polymerized polynucleotides (IRADYN) formulation.

Inclusion Criteria:

• Aged between 40 and 80 years (inclusive, ≥ 40 and ≤ 80 years);
• Symptomatic knee osteoarthritis as defined by the American College of Rheumatology (ACR) criteria (for subjects with OA at both knees, the most painful one will be included in the study only, respecting Kellgren-Lowrance grade II or III);
• Ambulant without assistance;
• Kellgren-Lawrence grade II or III on X-ray performed at maximum 6 months before screening;
• Visual Analogue Scale (VAS) score knee pain ≥40 at screening and 30 days before;
• Oral/parenteral corticosteroid or NSAIDs (≤10 mg prednisone) administration at least 30 days before screening.
• Signed Informed consent

Exclusion Criteria:

• Unstable knee;
• Varus or valgus ≥ 15 degrees;
• Active malignancy;
• Knee trauma or lose body parts 1 year before screening;
• Rheumatoid Arthritis, avascular necrosis, fibromyalgia;
• Use of potent analgesics 15 days (different from ≤ 10 mg prednisone) before screening;
• Intra-articular HA, polymerized polynucleotides or corticosteroid injection within 6 months before screening;
• Arthroscopic or knee open surgery within 12 months before screening;
• Body Mass Index (BMI) ≥ 40 kg/m2;
• Active infection around the injection site;
• Use of anticoagulants or history of thrombocytopenia;
• Concomitant use of disease-modifying antirheumatic drugs (DMARDs), anaesthetics;
• Known sensitivity to polymerized polynucleotides;
• Pregnancy, breast feeding.