A Locally Injected Bradykinin Antagonist for TReatment of OSteoarthritiS

Main Inclusion Criteria: * Male or female patients ≥40 years old. * Symptomatic primary knee osteoarthritis (ACR criteria) since ≥6 months prior to screening, Kellgren Lawrence Grade 2 or 3, and representing an indication for intra-articular drug injection. * \>50 mm VAS pain score assigned to the index knee at WOMAC VA 3.1-A1 (pain while walking on a flat surface). * \>125 mm VAS pain score assigned to the index knee at WOMAC VA 3.1 A subscore (total pain). * Pain in the index knee on at least 50% of the days in the month preceding the screening. Main Exclusion Criteria: * Patients with Kellgren \& Lawrence Grade I or IV (doubtful or severe) osteoarthritis of the knee. * Knee condition representing an indication for surgery * Patients with Inflammatory or crystal arthropathies, acute fractures, severe loss of bone density, bone necrosis. * Patients with isolated patella-femoral syndrome or chondromalacia. * Patients with OA predominant in the lateral compartment or any significant valgus deformity. * Patients with any other disease or condition interfering with the free use and evaluation of the index knee for the 3 month duration of the trial (e.g. cancer, congenital defects, spine osteoarthritis). * Major injury or surgery to the index knee within the previous 12 months prior to screening. * Severe hip osteoarthritis ipsilateral to index knee. * Any pain \>30 mm VAS that could interfere with the assessment of index knee pain (e.g. pain in any other part of the lower extremities, pain radiating to the knee). * Any pharmacological or non-pharmacological treatment started or changed during 4 weeks prior to randomisation or likely to be changed during the duration of the study * Use of systemic or topical corticosteroids \>10 mg prednisolone equivalent per day during 30 days prior to randomisation. * Use of any pain or OA medication (e.g. NSAIDs, COX-2 inhibitors, analgesics) during 1 or 2 weeks prior to randomisation. * Any intra-articular or local periarticular punction, injection or surgery to the index knee during the 6 months prior to screening.