The goal of this clinical study is to evaluate the effectiveness of the properties that support the functional state of the joints and the safety of the dietary supplement for food ARTNEO®, oral capsules, in patients with stage II-III primary osteoarthritis of the knee joint.

The main questions it aims to answer are:

1. To evaluate the effectiveness of the joint functional state-supporting properties of dietary supplement ARTNEO®, capsules for oral administration, in patients with stage II-III primary osteoarthritis of the knee joint;
2. To evaluate the safety of dietary supplement ARTNEO®, capsules for oral administration, in patients with stage II-III primary osteoarthritis of the knee joint.

Participants will be randomly distributed equally among two groups:

• Group 1 "ARTNEO" (106 people): patients take the study dietary supplement ARTNEO®, 1 capsule 1 time per day for 6 months;
• Group 2 "Placebo" (106 people): patients take placebo 1 capsule 1 time per day for 6 months.

Inclusion Criteria:

1. Voluntarily signed informed consent to participate in the study;
2. Men and women in postmenopause, aged 40-75 years, capable of independent movement, BMI 18-30 kg/m2;
3. Verified primary gonarthrosis according to the American College of Rheumatology criteria at least 6 months before enrollment in the study (in the presence of pain in the knee joint and radiological signs of gonarthrosis in combination with one of the following signs: crepitus in the joint or morning stiffness in the joint for less than 30 min);
4. II-III radiological stage of gonarthrosis according to the Kellgren-Lawrence classification with a predominant lesion of the medial tibiofemoral area of the knee joint;
5. Severity of pain in the assessed knee joint at the time of the screening visit from 40 or more on 100-mm VAS while walking;
6. Ability to understand the rules of the study, willingness to follow them;
7. Willingness to limit the diet (soy, avocado, passion fruit, pineapple, turmeric, linseed, rapeseed, soybean oils, chia seeds, walnuts, decoction of willow bark, pine, wormwood, L-carnitine, etc. should be excluded);
8. Consent of the men during the study and within 30 days after its completion to use the methods of contraception described in the protocol of this study.

Exclusion Criteria:

1. Individual intolerance to the active or excipients of the ARTNEO® dietary supplement (undenatured type II collagen + methylsulfonylmethane + Boswellia serrata extract + vitamin C + Vitamin D3), placebo and the "rescue" drug ibuprofen;

2. Intolerance to eggs, poultry, shellfish;

3. History of trauma or surgery on the target knee joint (other than diagnostic arthroscopy more than 60 days old at study entry), expected surgery (within 6 months following inclusion);

4. Coronary artery bypass grafting in medical history;

5. Diseases, the presence of which, from the point of view of the research physician, puts the patient's health at risk in case of participation in the study or potentially complicates the interpretation of the results of the study (may affect the assessment of endpoints):

   • Known or suspected malignancy at the time of screening or in the previous 2 years, other than completely healed skin cancer in situ;
   • History of gouty arthritis;
   • Malabsorption syndrome, celiac disease, short bowel syndrome, intestinal lymphangiectasia;
   • Peptic ulcer of the stomach and duodenum (in the acute phase or in the acute stage), gastrointestinal bleeding, Crohn's disease, ulcerative colitis at the time of screening or according to medical history for the last 4 months before the screening visit;
   • Hemophilia, hemorrhagic diathesis at the time of screening or according to medical history for the last 4 months before the screening visit, constant use of anticoagulants and antiplatelet agents according to the medical history for the last 4 months before the screening visit;
   • Ischemic heart disease, cerebrovascular disease in the acute stage or decompensation at the time of screening or according to medical history for the last 4 months before the screening visit;
   • Chronic obstructive pulmonary disease (COPD), bronchial asthma according to medical history;
   • Diagnosed moderate or severe chronic renal failure at the time of screening or based on medical history in the last 4 months prior to the screening visit;
   • Moderate to severe hepatic dysfunction as determined by history (any acute liver disease, toxic liver disease, cirrhosis, decompensated liver failure) at the time of screening or from medical history in the last 4 months prior to the screening visit;
   • The presence of rheumatological diseases according to the medical history;

6. Mental and / or neurological diseases with partial or complete loss of legal capacity;

7. Presence or suspicion of drug, alcohol or drug addiction;

8. Intra-articular injection into the target knee joint:

   • Hyaluronates - less than 6 months prior to randomization;
   • Glucocorticosteroids less than 1 month prior to the randomization visit.
   • PRP therapy - less than 6 months prior to randomization

9. The need for constant use of glucocorticoids in any dosage form;

10. Use, including single use, of paracetamol, NSAIDs in any dosage form, and other pain medications within the last 48 hours prior to the randomization visit. Use within 7 days before randomization of certain natural products (such as soy, avocado, passion fruit, pineapple, turmeric, linseed, rapeseed, soybean oils, chia seeds, walnuts, decoction of willow bark, pine, mugwort), L-carnitine;

11. The use of glucosamine or chondroitin during the last 3 months before randomization with a course duration of more than 3 months (if the duration of the course of glucosamine or chondroitin was less than 3 months, then this therapy must be abandoned throughout the study from the moment of the screening visit);

12. Use of ω-3 polyunsaturated fatty acid preparations within 14 days prior to randomization, therapeutic doses of fish oils (≥ 2 g/day) and shark cartilage preparations within 6 months prior to randomization (except vitamin D3);

13. Participation in any clinical trial currently or in the previous 30 days or 5 half-lives (whichever is longer) prior to the Screening visit;

14. History of oral undenatured type II collagen therapy in the last 4 months prior to the screening visit;