Knee osteoarthritis (KO) is a common disabling condition in the elderly. Its treatment includes medications, surgery, and complementary therapies. Nonsteroidal anti-inflammatory drugs, which are often used, are not completely effective and are associated with adverse effects. Black cumin (Nigella sativa, Ranunculaceae) oil and its active components, especially thymoquinone, have antioxidant, anti-inflammatory, and analgesic properties. These authors conducted a crossover, clinical trial to evaluate the topical application of black cumin oil (Barij-e-Kashan; Kashan, Iran) and oral acetaminophen on KO in elderly patients living in a nursing home in Sabzevar City, Iran. The study was conducted from November 21, 2014, to January 20, 2015.
Patients were eligible for the study if they were older than 65 years and had been diagnosed with KO using the American College of Rheumatology criteria, which included knee pain on most days of the preceding month, crepitus on active motion, morning stiffness for less than 30 minutes, and bony enlargement found on physical examination of the knee. Forty-two patients with a mean age of 75.66 ± 8.9 years were enrolled in the study. Two patients did not comply with the study protocol and were excluded from the final analysis.
During phase 1 of the study, the patients in group 1 applied 1 mL black cumin oil to the knee 3 times daily every 8 hours for 3 weeks, massaging the knee for 5 minutes with the palm of the hand in a clockwise direction at the front and sides of the joint. [Note: The Intervention section of the article says 1 week; however, the Discussion section and abstract say 3 weeks.] The patients in group 2 were instructed to take 1 tablet of 325 mg acetaminophen 3 times daily every 8 hours for 3 weeks. Following a 1-month washout period, each group then followed the alternate treatment protocol.
Pain intensity was measured using a visual analogue scale before and after the 2 phases of the study, with 0-3 indicating mild pain; 4-5, moderate pain; and 8-10, severe pain. The authors report that significant improvements in knee pain were seen after both treatments (P = 0.0001). The improvement in pain intensity was significantly greater in the black cumin oil group compared with the acetaminophen group (P = 0.01).
Thymoquinone in black cumin is reported to inhibit oxidative stress and exhibit an analgesic effect on the central nervous system of study rats with experimental allergic encephalomyelitis.1 In another cited animal study, the analgesic and anti-inflammatory effects of black cumin were attributed to its polyphenols.2
“This study showed that topical use of Nigella sativa oil can be more effective in reducing knee pain in elderly patients than acetaminophen, which is typically used as a safe supplement for the elderly,” conclude the authors. The mechanisms involved should be explored further in studies of longer duration.
This study was funded by Sabzevar University of Medical Sciences (Sabzevar, Iran).
1Mohamed A, Shoker A, Bendjelloul F, et al. Improvement of experimental allergic encephalomyelitis (EAE) by thymoquinone; an oxidative stress inhibitor. Biomed Sci Instrum. 2003;39:440-445.
2Ghannadi A, Hajhashemi V, Jafarabadi H. An investigation of the analgesic and anti-inflammatory effects of Nigella sativa seed polyphenols. J Med Food. 2005;8(4):488-493.
Kooshki A, Forouzan R, Rakhshani MH, Mohammadi M. Effect of topical application of Nigella sativa oil and oral acetaminophen on pain in elderly with knee osteoarthritis: a crossover clinical trial. Electron Physician. 2016;8(11):3193-3197.