The knee osteoarthritis is a frequent degenerative condition that mainly affects subjects over 60, population often weakened by numerous comorbidities and concomitant treatments, justifying the development of new therapies.

The viscosupplementation is a symptomatic treatment for knee osteoarthritis ; the objective of this intra-articular injection of hyaluronic acid is to reduce knee pain and improve mobility. In practice, there are two protocols to administer viscosupplementation : in a single injection or in three injections performed weekly.

The present clinical investigation has the objective to evaluate the safety and efficacy of use of Pandora, a hyaluronic acid associated with tranexamic acid, in a single injection (HO-1) or in three injections performed weekly (HS-3), compared to a referred and commercialized medical device.

This clinical investigation is a prospective, multicenter, randomized, parallel groups study of a class III Medical Device.

This study is designed to compare the safety of use and the efficacy of Pandora in its two forms : in a single injection (HO-1) or in three injections (HS-3) to a single intra-articular injection of 2.5 ml (SINOVIAL®ONE)

A descriptive analysis will be carried out to characterize the demographic data, the history of the disease and its treatments, the clinical and radiological data of the patients at inclusion.

The efficacy of Pandora will be demonstrated by describing the variation of WOMAC A1 score "walking pain" of target knee in repeated measures.

In total, 252 participants will be enrolled across 40 study centers in France and Monaco.

The total duration of subjects' participation is 12 months ; overall study duration including the enrollment period is expected to take approximately 24 months.

Inclusion Criteria :

• Patient aged between 35 and 85 years.
• Body mass index (BMI) < 35 kg.m2.
• Medial or lateral femoro-tibial knee osteoarthritis, diagnosed according to the American College of Rheumatology criteria, radiological stage 2 and 3 according to the Kellgren-Lawrence criteria modified by Felson on an X-ray, of the knee in extension, less than 6 months old.
• Knee osteoarthritis responsible for walking pain in the target knee, assessed between 4 and 8 inclusive on an 11 points numerical scale (0 = none to 10 = extreme).
• Unilateral or bilateral knee osteoarthritis if the walking pain in the contralateral knee is < 3 based on 11 points numerical scale (0-10).
• Ambulatory patient able to walk 50 meters without a cane, crutch or walker.
• Patient giving his informed consent.
• Patient agreeing to follow-up study visits.
• Patient affiliated to the health social security system or beneficiary of such plan.
• Patient requiring viscosupplementation according to the investigator.

Exclusion Criteria :

• Patient presenting knee osteoarthritis without impingement joint space narrowing of the femoro-tibial compartment (modified Kellgren stage 0-1) or with complete impingement joint space narrowing on the knee weight-bearing radiograph in extension (modified Kellgren stage 4).
• Patient with bilateral symptomatic gonarthrosis with walking pain of contralateral knee > 3.
• Patient with stage 4 patello-femoral osteoarthritis associated with femoro-tibial osteoarthritis.
• Patient with a flare of osteoarthritis of the target or contralateral knee.
• Patient who received viscosupplementation or Platelet Rich Plasma (PRP) injection, in the target knee, in the 6 months prior to inclusion.
• Patient who received an intra-articular injection of corticosteroids in the target knee in the 2 months prior to inclusion.
• Patients with a skin condition or a wound next to or near the injection site.
• Patients refusing to discontinue treatment with NSAIDs or cox-2 inhibitors during the follow-up period.
• Patient receiving treatment with level III analgesics (strong opioids).
• Patients receiving treatment with diacerhein, avocado and soy unsaponifiables, glucosamine or chondroitin initiated less than 2 months prior to inclusion.
• Patient with hypersensitivity to hyaluronic acid or tranexamic acid.
• Patient with a history of seizures.
• Patient who had arthroscopy of the target knee or major trauma to the target knee during the 3 months preceding inclusion.
• Patient scheduled to undergo surgery, for any cause, of the target knee or other joint of the lower limbs, planned within 6 months of inclusion, likely to interfere with follow-up or evaluation of the patient in the study.
• Patient with Fibromyalgia.
• Patient with an active neurological or vascular musculoskeletal disorder (such as rheumatoid arthritis, lupus, psoriatic arthritis, spondyloarthritis or any other autoimmune disease, Paget's disease, gout, coxopathy, tendinopathy of the lower limb, sciatic or crural radiculalgia) which, in the opinion of the investigator, would be likely to disrupt regular monitoring and/or interfere with the measurement of evaluated knee treatment efficacy.
• Patient with serious hemostasis disorders, venous or lymphatic stenosis of the lower limbs, history of thromboembolic disease - phlebitis or pulmonary embolism - or a high risk of thromboembolism.
• Patients with renal insufficiency.
• Patients with all evolving general condition as cardiac, digestive, endocrine, haematological or broncho-pulmonary which, in the opinion of the investigator, would be likely to disrupt regular monitoring and/or interfere with the measurement of evaluated knee treatment efficacy.
• Breastfeeding patient, pregnant or wishing to be during the 12 months of the study.
• Patients of childbearing age, sexually active without contraception.
• Patients unable to give personal consent.
• Patients participating or having participated in interventional research and whose follow-up ended within 2 months prior to inclusion.

Single blind