This clinical trial study is conducted in Vietnam to assess the efficacy and tolerability of Proteoglycan F in the treatment of primary knee osteoarthritis. 72 outpatients (40-80 years old) were diagnosed with primary knee osteoarthritis and met the American College of Rheumatology 1991 criteria. Patients have to be symptomatic for ≥ 3 months before enrollment and have a radiologic grade II and III measured by the Kellgren-Lawrence criteria. The study was designed as a Prospective, Randomized, Double-blind Controlled trial. Each patient will be follow during 24 weeks of intervention, follow-up every 4 weeks.

With the trend of aging population and progressive increment of obesity in Vietnam, the number of patients suffering from osteoarthritis most likely will substantially increase in the coming years. Therefore, it is necessary to having a suitable and effective approach of treatment for osteoarthritis by using functional foods.

Proteoglycan is the basic substance of articular cartilage. Proteoglycans are mostly found in the extracellular matrix of animal tissue as cartilage, or in the blood vessels and brain. These substances are a key ingredient in the regeneration of cartilage, inhibiting the enzyme elastase - an intermediate that causes degenerative articular cartilage and reduces the formation of free oxygen radicals in cartilage tissue. Therefore, the effects are on inhibiting cartilage calcification, regenerating cartilage and relieving pain for cartilage degeneration, promoting cartilage metabolism, forming cartilage.

Previous studies have demonstrated that proteoglycan enhances fluid not only to alleviate arthritis pain but also prevent complications, as it gradually overcomes the damage of joint bone, resolves inflammation, helps relieve pain and prevent osteoarthritis, osteoporosis effectively. Otherwise, industrially extracted Proteoglycans presents to be safe and valuable for future studies of its function. Therefore, this randomized, double-blind controlled trial is conducted in Vietnam to assess the efficacy and tolerability of Proteoglycan F in the treatment of primary knee osteoarthritis.

Inclusion Criteria:

• 40-80 years old
• Diagnosed with primary knee osteoarthritis and met the American College of Rheumatology 1991 criteria
• Patients have to be symptomatic for ≥ 3 months before enrollment
• Have a radiologic grade II and III measured by the Kellgren-Lawrence criteria

Exclusion Criteria:

• Patients with secondary knee osteoarthritis
• Patients with grade-I and IV osteoarthritis (Kellgren-Lawrence)
• Patients having joint lavage, arthroscopy, or treatment with hyaluronic acid or other disease modifying agents during the previous 6 months, or treated with intra-articular corticosteroids during the past 3 months, will be excluded from the study.
• Patients have contraindications to Non-Steroidal Anti-Inflammatory Drugs
• Patients have hematologic disorders, renal disease, liver disease, diabetes mellitus, acute illness, other rheumatic diseases, disabling comorbid conditions that would make it impossible for the patient to visit the research center.
• Pregnancy.

Will individual participant data be available (including data dictionaries)?

• Yes

What data in particular will be shared?

->Individual participant data that underlie the results reported in this article, after deidentification (text, tables,figures, and appendices).

What other documents will be available?

-> Study Protocol

When will data be available (start and end dates)? --> Beginning 9 months and ending 36 months following article publication.

With whom?

-> Investigators whose proposed use of the data has been approved by an independent review committee ("learned intermediary") identified for this purpose.

For what types of analyses?

-> For individual participant data meta-analysis

By what mechanism will data be made available?

-> Not applicable