Knee osteoarthritis is a common cause of disability in patients who are often young and active. Surgery being an option only for the most severe cases, there is little alternative in case of failure of recommended medication. Inflammatory hypervascularization of the joint is a known source of pain. Temporary embolization of intra-arterial inflammatory hypervascularization has been used since 2012 with good results on pain relief to treat patients with musculoskeletal disorders that are resistant to conventional treatments. Lipiodol® has transient embolizing properties when in emulsion with a contrast agent. It has been used as an emulsion with chemotherapy for the treatment of metastases and primary intra-arterial liver cancer (chemo-embolization) for many years without serious side effects. We hypothesized that Lipiodol® in emulsion could serve as a temporary embolization agent for the treatment of inflammatory hypervascularization responsible for musculoskeletal disorders in humans.

It is a Phase 1, Single-Arm, Open-label, Multicenter Interventional Prospective Study.

In order to ensure the best possible patient safety, a sequential inclusion of the first 6 patients is planned. Thus, the inclusion of each subsequent patient (patient 2-6) will only be considered after reviewing previously included patient safety data. Safety data after the inclusion of each patient (after a step-back of at least one week), as well as the cumulative review of previously included patient safety data, will be brought to the attention of all investigators involved in this research.

In addition, the following information will be transmitted to the Competent Authority without delay:

• a review of the safety and efficacy of the first 3 patients included with a step back for the last patient of at least one week after the administration of the experimental drug, as well as an argument as to the continuation of this research with regard to these data, with a discussion of the risks incurred in relation to the expected profit
• a review of the safety and effectiveness of the first 3 patients after the inclusion of the first 6 patients, as well as an argument as to the continuation of this research with regard to these data, with a discussion of the risks incurred compared to the expected benefit.

The patients will be embolized by the Interventional Radiology Department of the European Hospital Georges Pompidou (HEGP). Embolization will be performed by an experienced radiologist during a conventional hospitalization or a day hospitalization. A clinical follow-up will be carried out at 1 week, 1 month and 3 months after embolization by clinics and patient self-assessment (WOMAC, SF-36).

Inclusion Criteria:

• Diagnosis of primary inflammatory knee osteoarthritis of the target joint defined by a knee osteoarthritis according to the American College of Rheumatology (ACR) classification and a score ≥ 2 according to the classification of Kellgren and Lawrence
• Patient not eligible for surgery (or refusing surgery)
• Analog Visual Scale (VAS) pain ≥ 40 mm despite analgesic treatment for at least 3 months
• Failure or intolerance of treatment with NSAIDs and/or tramadol and/or acetaminophen, and/or failure or intolerance or patient refusing strong opioids medication (morphine, codeine)
• Failure or patient refusal of corticosteroid infiltration
• Patient who has signed an informed consent

Exclusion Criteria:

• Patient who is unable or unable to comply with the follow-up schedule
• Infiltration of target joint less than three months old
• Treated hyperthyroidism
• Traumatic injury, hemorrhage or bleeding less than 1 week old in the target joint
• Known arterial disease of the lower limbs stage ≥ 2 according to the classification of Leriche and Fontaine
• Known severe allergy to Lipiodol® and/or iodized contrast product
• Known severe kidney failure (creatinine clearance < 30 ml/min)
• Pregnant or breastfeeding woman
• Patient not affiliated with a French Medicare
• Patient benefiting from legal protection
• Participation in another interventional research

Individual participant data (IPD) that underlie results in publication could be shared. IPD detailed in the protocol of a planned metaanalysis could be shared.

2 years after the last publication

Data sharing must be accepted by the sponsor and the PI based on a scientific project and scientific involvement of the PI team. Collaboration will be fostered.

Data sharing must respect the agreements made with funders.

Teams wishing obtain IPD must meet the sponsor and IP team to present scientific (and commercial) purpose, IPD needed, format of data transmission, and timeframe. Technical feasibility and financial support will be discussed before mandatory contractual agreement.

Processing of shared data must comply with European General Data Protection Regulation (GDPR).

Teams wishing obtain IPD must meet the sponsor and IP team to present scientific (and commercial) purpose, IPD needed, format of data transmission, and timeframe. Technical feasibility and financial support will be discussed before mandatory contracting