This prospective study was planned to carried out among the patients with grade II and III (Kellgren Lawrence classification) osteoarthritis of the knee attending outpatients clinic to evaluate the effectiveness and safety of viscosupplementation with intra-articular hyaluronic acid injection.

The study was designed as prospective, single-center, single-arm, open-label, observational study. The patients with grade II and III (Kellgren Lawrence classification) osteoarthritis of the knee attending outpatients were planned to enroll the study. Patients between the age 18-80 years who did not achieve remission of pain despite receiving the first-line treatment for gonarthrosis including nonsteroidal anti-inflammatory drugs medication, activity modification and ice, were planned to included in the study. A single dose of HA will be injected into the target knee joint. Clinical evaluation will be done using the Western Ontario and McMaster Universities Arthritis Index (WOMAC) and the short form-36 questionnaires (SF-36 v2) at baseline, 3 months and 6 months by a clinical secretariat.

Inclusion Criteria:

• Patients Age should not be less than 18 years.
• Patients must be able to understand and follow the study procedures and must provide written informed consent.
• Radiologically Grade II or III osteoarthritis of knee according to the Kellgren and Lawrence classification.
• Mild to moderate documented diagnosis of knee osteoarthritis that fulfill the ACR (American College of Rheumatology) criteria.
• Patients with consistent symptoms (joint pain, crepitus, swelling, effusion alone or combination of these symptoms) of knee osteoarthritis for at least 3 months prior to screening. If bilateral knee pain is present, the more painful knee will be selected.
• Patients who are willing to discontinue all non-steroidal anti-inflammatory drugs (NSAIDs) or other analgesic medication taken for any condition, including their knee pain. However patients will be allowed to use only acetaminophen or aspirin as a rescue pain medication during the study period. The patients must abstain from medication use 24 hours prior to any study visit.

Exclusion Criteria:

• Patients with secondary osteoarthritis of the knee according to ACR criteria.
• Pregnant or lactating women, and women of childbearing potential not willing to use adequate contraception.
• Patients unable to stay in the study for 6 months, non- cooperating, not able to understand
• Patients having previously undergone surgery on target knee, including arthroscopy.
• Patients with neurological deficit in the lower extremities, with primary inflammatory joint disease, intra-articular tumours.
• Any severe systemic disease(s).
• Any significant osteoarthritis symptoms in other joints apart from the target knee which may require pharmacological treatment during the study.
• Patients who have received intra-articular hyaluronic acid within the previous 6 month and/or intra-articular steroids or articular lavage in the target knee within the previous 3 months prior to their inclusion in the study.
• Administration of glucosamine sulphate, chondroitin sulphate and diacerein within the 3 months prior to their inclusion in the study.
• History of allergy or hypersensitivity to hyaluronic acid.
• Participation in any clinical study in the last 3 months and any surgery scheduled in the next 8 months that can affect directly the result of the present study.

The patients with grade II and III (Kellgren Lawrence classification) osteoarthritis of the knee attending outpatients clinic