IRCT20080901001157N13 IRCT 2018-03-27 Iranian academic center for education culture and research Effect of Nigella sativa oil on knee osteoarthritis Effects of oral Nigella sativa seed oil on osteoarthritis indexes in patients suffering from knee osteoarthritis 2018-04-20 anticipated 80 Complete https://irct.ir/trial/29240 interventional Randomization: Randomized, Blinding: Double blinded, Placebo: Used, Assignment: Parallel, Purpose: Treatment, Randomization description: For randomization, a random number table and block randomization method is used. In this method, eligible patients are divided into blocks of 4 patients. There is no significant difference between the patients in each block in terms of total pain score index . To half of the patients in a block, from the random numbers table, the numbers whose first digits are even and to other half patients, the numbers that first digit are odd are allocated. Then, half of the patients in the block which the first digit are even the Nigella sativa oil are assigned and the other half of the patients which the first digit are odd are assigned to the placebo, Blinding description: Letters A or B are labeled on drug or placebo emulsion bottles. Other specifications on the labels are completely identical. Physician, nurse, patient, data collector and those who evaluate the outcome, are unaware of the nature and meaning of the letters A or B on the labels. Only the main investigator knows the nature of the labels. Patients are aware that they are either in the drug or in the placebo groups, but they are not aware of the type of group they are in. 2-3 Osteoarthritis. Intervention 1: Intervention group: Nigella sativa oil emulsion; Patients taking a tablespoon of nigella sativa oil emulsion three times a day after food (5 ml nigella sativa oil daily) for one month. Intervention 2: Placebo group: Placebo emulsion; Patients taking a tablespoon of placebo emulsion three times a day after food ( total 5 ml mineral oil taking per day) for one month. Undecided - It is not yet known if there will be a plan to make this available Justification or reason for indecision in sharing IPD is There is no further information