Prospective, Interventional, Non-Randomized, Open Label, Single Group Assignment, Single Center.

Inclusion Criteria:

• 55 to 79 years of age
• Symptomatic Knee osteoarthritis
• VAS pain intensity is at least 40 mm on a 100 mm scale
• Must be physically and mentally willing and able to comply with post-operative rehabilitation and routinely schedule clinical and radiographic visits.

Exclusion Criteria:

• Any known tumor of the ipsilateral knee.
• Any known infection of the treated knee.
• Osteoarthritis of the operated knee Kelgren Lawrence < grade 2.
• Chemotherapy treatment in the past 12 months.
• Patients who are sensitive to ozone.
• Pregnant women, or breastfeeding women.
• Evidence of any significant systemic disease (such as but not limited to HIV infection, hepatitis infection or HTLV infection), known coagulopathies, that might compromise the Subject's welfare.
• Substance abuse or alcohol abuse.
• Participation in other clinical trials in parallel to this study.

the outcome assessor was not aware of the therapy administered