Knee osteoarthritis is a common condition that causes pain, stiffness, and difficulty with daily activities. Ozone injection therapy is a minimally invasive treatment that has been increasingly used to relieve symptoms in people with knee osteoarthritis. However, it is not clear whether different ozone concentrations produce different treatment outcomes.

In this study, we compared the effects of two commonly used ozone concentrations (15 μg/mL and 25 μg/mL) in patients with knee osteoarthritis. A total of 159 patients received intra-articular ozone injections and were followed for 3 months. Pain, physical function, and quality of life were assessed before treatment and at 1 and 3 months after the injections.

Background: Knee osteoarthritis (KOA) is a prevalent joint disorder globally, resulting in pain and disability, with various treatment options available. Intra-articular ozone (O2-O3) administrations are an efficient therapeutic approach commonly employed in this condition. With this study, we aimed to compare the effect of varying ozone concentrations on treatment outcomes.

Method: This multicenter single-blind, cohort study was conducted at two distinct university hospitals between May 2023 and September 2024. Patients who underwent intra-articular knee ozone injection were examined and divided into two groups as 15 μg/ml (Group A) and 25 μg/ml ozone (Group B). Participants' pain scores were measured by Numeric Rating Scale (NRS), functional status by Western Ontario and McMaster Universities Arthritis Index (WOMAC) and quality of life by Short Form-12 (SF-12) before and at 1 and 3 months following ozone therapy.

Inclusion Criteria:

• Patients aged 50-85 years with a diagnosis of primary knee osteoarthritis according to the American College of Rheumatology [12] criteria, symptomatic knee with KL [13] grades II, III and IV, who underwent intra-articular ozone treatment.

Exclusion Criteria:

• Patients with a history of any intra-articular injection within 3 months before the first ozone injection, a history of previous knee surgery, a diagnosis of malignancy, missing follow-up parameters, bilateral intra-articular knee ozone injection, a secondary knee osteoarthritis diagnosis (trauma, inflammatory joint disease, etc.), patients without demographic and clinical data, or direct radiographs.

The underlying datasets related to the results of the research paper can be shared as needed. If someone would like to request the data from this study, they can contact the corresponding author, Ridvan Isik, MD.