This is a single-center, prospective, randomized, double blind, placebo control study. The aim of this study is to assess the effect of fish oil capsules on pain intensity and postoperative analgesics consumption in patients after knee replacement surgery.

The study population will be adult are referred for knee replacement surgery due to osteoarthritis of the knee.

Primary outcome:

Post surgical pain level and analgesics use

Secondary outcomes:

1. Pain levels and analgesic use at six weeks and 3 months after surgery
2. ω3 incorporation into blood cell membranes(RBC)
3. Stress and inflammation markers
4. Rates of postoperative complications

Study Procedure :

Enrolled patient will be randomly divided into a control group and intеrvention group during preoperative clinic visit. Each patient will receive total 150 capsules (5 capsules per day) accordingly to randomized group.

Patients in treatment group will receive Fish Oil capsules. Patients in control group will receive placebo capsules.

Inclusion Criteria:

Patients are referred for knee replacement surgery due to osteoarthritis of the knee

• Exclusion Criteria:

  • Use of steroids, NSAIDs two weeks before surgery, antidepression drugs, antiepileptic drugs, coumadin
  • Diabetic neuropathy
  • Herpes-zoster/ post-herpetic neuralgia
  • n-3 supplements use