The effect of curcumin ointment on knee pain in older adults with osteoarthritis: a randomized placebo trial

BACKGROUND: Some studies have shown the effect of oral administration of curcumin on knee pain. However, limited studies are available on the effect of topical curcumin. This study aimed to investigate the effect of curcumin ointment on knee pain in older adults with osteoarthritis. METHODS: This double-blind randomized placebo trial was conducted on 72 older adults with knee pain associated with osteoarthritis. The subjects were randomly assigned into an intervention and a placebo group to apply either curcumin 5% ointment or Vaseline ointment twice daily for 6 weeks. Using a Visual Analog Scale, the severity of knee pain was measured at the beginning of the study, at the end of the fourth and sixth week. Data were analyzed using descriptive and inferential methods. RESULTS: The mean baseline knee pain intensity was not significantly different between the two groups (P = 0.15). The mean pain intensity was significantly lower in the intervention group than in the placebo group at the third measurement (P = 0.02). The repeated-measures analysis showed that over time, the curcumin significantly decreased the mean pain intensity in the intervention group (P = 0.001). The mixed model showed an absolute difference of 1.133 (i.e. 11.33 mm) score which signifies a medium effect size and that the patient in the intervention group achieved the minimal clinically important difference. CONCLUSION: Topical administration of curcumin 5% ointment can significantly reduce knee pain in older adults with knee osteoarthritis. Curcumin ointment can be used as an alternative treatment in older adults with knee pain associated with osteoarthritis. TRIAL REGISTRATION: Retrospectively registered in the Iranian Registry of Clinical Trials (IRCT) (IRCT20100403003618N6, 2019-03-08), https://en.irct.ir/trial/37155