Hyaluronic acid is a polysaccharide naturally present in several human tissues such as cartilage. It is the major constituent of synovial fluid and provides its viscosity and elasticity. In traumatic and degenerative joint diseases, the amount of hyaluronic acid is reduced. The consequent loss of viscosity by the synovial fluid may be the cause of painful symptoms. HyaleXo action, according to its composition (sodium hyaluronate of very high molecular weight), may restore the viscoelastic properties of synovial fluid, attenuate pain and improve the mobility of the joint. These characteristics allow HyaleXo to be used for the symptomatic relief of pain in patients suffering from osteoarthritis (OA) or degenerative joint diseases causing an alteration of the functionality of the synovial fluid.

The patient will be treated with HyaleXo as reported in the Instruction for use (IFU) of the device: via injection once a week for 3 weeks using standard technique. The patient pain management strategy should be according to the standard clinical practices and remains at the discretion of the investigator.

The Research Question of the present study is the following: in a population of men and women suffering from painful knee osteoarthritis or degenerative joint disease will very high molecular weight fraction of sodium Hyaluronate (HyaleXo) significantly decrease and / or relieve the pain after 1,6,12 weeks and 6 months of the third injection?

Inclusion Criteria:

1. Patients older than 18 years old (inclusive ≥ 18 years).
2. Men or women.
3. Patients suffering from painful chronic idiopathic symptomatic degenerative joint diseases (clinical evidence) OR knee osteoarthritis (as defined by the American College of Rheumatology (ACR) criteria); for patients with OA at both knees, only the most painful one will be included in the study.
4. VAS knee pain ≥ 40 mm at screening and 30 days before.
5. Patients willing and able to comply with study terms.
6. Patients willing to discontinue all other OA treatments

Exclusion Criteria:

1. Patients that are unable or unwilling to provide informed consent, and/or patients participating in a concurrent clinical trial and/or patients who have participated in a similar clinical trial within the last days.
2. Patients with known hypersensitivity to any components of investigational product.
3. Patients who are pregnant or breastfeeding. Patients with infected or severely inflamed joints.
4. Patients with skin diseases or infections in the area of the injection site.
5. Patients with hepatic failure or history thereof.