this is a randomized double blinded trial which is conducted to measure the efficacy of topical virgin olive oil on osteoarthritis of knee that will be done in contrast to standard piroxicam gel.

application of herbal product has old history in therapy of human diseases. olive oil is one of the important diet in Iran which its efficacy in reducing of rheumatic pains was pointed out by Avicenna in 10th century. Nevertheless, its efficacy is not confirmed by scientific study.

in this double blinded study, 200 patients with diagnosed osteoarthritis of knee will be recruited that will randomly be assigned in piroxicam or olive oil group. the piroxicam gel or olive oil will be repackaged in anonymous tubes, which only recognizable via codes. the patients or visiting clinicians will be unaware of content of tubes. the final assessor will be blind to groups and interventions.

the efficacy of therapies will be evaluated by means of WOMAC and PGs standard questionnaires.

Inclusion Criteria:

• men and non-pregnant women, age 40-85 years with primary OA of at least one knee, and a flare of pain after withdrawal of prior therapy with either an oral NSAID or acetaminophen (used at least 3 days per week during the previous month).

Exclusion Criteria:

• secondary arthritis related to systemic inflammatory arthritis (including rheumatoid arthritis, psoriatic arthritis, post-infectious arthritis and metabolic arthritis, traumatic arthritis or surgical joint replacement); corticosteroid use:

  • oral corticosteroid within the previous 14 days, or
  • intramuscular corticosteroid within 30 days, or
  • intraarticular corticosteroid into the study knee within 90 days,
  • intra-articular corticosteroid into any other joint within 30 days, or
  • topical corticosteroid at the site of application within 14 days;

• ongoing use of prohibited medication including NSAID, other oral analgesic, muscle relaxant, or low-dose antidepressant for any chronic pain management; - ongoing use of glucosamine or chondroitin (unless used continuously for 90 days prior to study entry);

• sensitivity to diclofenac, acetylsalicylic acid (ASA) or any other NSAID, acetaminophen, dimethyl sulphoxide, propylene glycol, glycerine or ethanol; clinically-active renal, hepatic or peptic ulcer disease;

• history of alcohol or drug abuse;

• lactation;

• concomitant skin disease at the application site;

• current application for disability benefits on the basis of knee osteoarthritis; fibromyalgia; other painful or disabling condition affecting the knee;