This post-market clinical follow-up, open-label, multicenter clinical investigation is designed to investigate the effectiveness, safety and tolerability of ThermaCare® Knee Heatwraps in the painful knee joint due to osteoarthritis. Approximately 80 patients, 19-69 years old inclusive, with moderate knee osteoarthritis (without acute flares or inflammation) will be enrolled. The overall duration of the investigation is expected to be 11 days, including screening days. The maximum treatment duration for each patient is 7 days (8h/d).

Inclusion Criteria:

• Signed written informed consent before inclusion in the investigation.
• Any gender, any ethnic origin, 19-69 years old inclusive.
• Body Mass Index 18.5-40 kg/m2 inclusive.
• Full comprehension: ability to comprehend the full nature and purpose of the clinical investigation.
• Patient with diagnosis of mono or bilateral moderate knee osteoarthritis with knee pain intensity > 40 mm on a 0-100 mm VAS, able to independently ambulate without walking aid.
• Availability of a radiography of the selected knee not older than 6 months.
• Patient is either not of childbearing potential or must agree not to start a pregnancy from the signature of the informed consent up to the final visit

Exclusion Criteria:

• Clinically significant abnormal physical findings which could interfere with the objectives of the investigation
• History of anaphylaxis to drugs or allergic reactions in general, which could affect the outcome of the clinical investigation.
• Significant history of diseases that may interfere with the aim of the clinical investigation.
• History of (in the last 6 months) or ongoing intra-articular injection involving the selected knee. History of ongoing physical therapy involving the selected knee.
• Presence of flares, inflammation, effusion and swelling at the selected knee.
• Any skin injury, wound, irritation, rash, bump, sore and/or discoloration at the application area.
• Surgery at the selected knee in the 12 months preceding the clinical investigation.
• Any medication that could interfere with the investigation procedures or investigation outcome.
• Use of other hot or cold therapies for the selected knee.
• Positive pregnancy test at screening; pregnant or breastfeeding women
• History of (within the past 12 months) or current drugs or alcohol abuse
• Individuals unable to fully understand all aspects of the investigation that are relevant to the decision to participate, or who could be manipulated or unduly influenced because of a compromised position, expectation of benefits or fear of retaliatory response.