The purpose of this study is to assess the safety, tolerability and efficacy of Lipocet® (food supplement) in patients with primary knee osteoarthritis grade 3 - 4

After being informed about the study, all patients giving written informed consent will undergo no more than a 1-week screening period to determine eligibility for study entry. Patients that meet inclusion criteria and do not have exclusion criteria will be randomized in a double-blind manner (participant and investigator) in a 1:1 ratio to Lipocet ® (once a day, 10 ml corresponding to 1500 mg of Cetylated fatty acids) or placebo (once a day, 10 ml) during 60 days of treatment.

Inclusion Criteria:

1. Signed Patient Information Sheet and Informed Consent Form

2. Patients with primary osteoarthritis classified according to ACR/EULAR criteria

3. Men or women aged ≥ 40 and ≤80 years

4. A disease severity grade 3 or 4 according to the Kellgren-Lawrence classification:

   • grade 0 (none): definite absence of x-ray changes of osteoarthritis
   • grade 1 (doubtful): doubtful joint space narrowing and possible osteophytic lipping
   • grade 2 (minimal): definite osteophytes and possible joint space narrowing
   • grade 3 (moderate): moderate multiple osteophytes, definite narrowing of joint space and some sclerosis and possible deformity of bone ends
   • grade 4 (severe): large osteophytes, marked narrowing of joint space, severe sclerosis and definite deformity of bone ends

5. Patients who are candidates for knee replacements can be included (this criterion is not mandatory)

6. Patients who mark the pain ≥ 4 cm on a VAS

7. Patients who are willing or able to follow doctor's instructions

8. Patients not participating in other clinical trials within 30 days before the screening

9. Patients who have received sufficient explanation for this clinical trial and agreed to participate

Exclusion Criteria:

1. BMI > 32
2. Systemic inflammatory diseases (e.g. fibromyalgia, etc.)
3. Progressive serious medical conditions (such as cancer, AIDS or end-stage renal disease)
4. Patients with major infections in the observation period
5. Renal diseases (serum creatinine concentration more than 1.2 times the upper limit of the normal range according to the central laboratory definition reference values)
6. Liver dysfunction (serum alanine or aspartate transaminase concentrations more than 1.5 times the upper limit of normal