Effect of Topical Hemp (Cannabis sativa L.) Seed Oil on Knee Osteoarthritis: A Randomized Double-Blind Controlled Trial

Purpose, and design: Knee osteoarthritis (OA) is one of the most common and debilitating diseases, especially in the elderly. Hemp seed oil is a plant product that has been used as a food or drug since ancient times because of its anti-inflammatory and analgesic properties.

Methods: A double-blind, active, placebo-controlled trial was done to assess the efficacy of hemp seed oil on knee OA. Ninety patients were randomly allocated to three groups; hemp seed oil, diclofenac gel, and placebo via a blocked randomization method, and were asked to apply the topical treatment daily for 2 months. The study participant underwent assessments before, and four and 8 weeks after the intervention. Evaluation included measurements of the heel-to-thigh distance, utilization of Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), and application of visual analog scale (VAS). Data analysis was performed using SPSS.24 and the significance level was considered as p < .05.

Results: All parameters, except heel-to-thigh distance, improved significantly in the hemp seed oil group compared to placebo group. Improvements in VAS and WOMAC parameters were not different comparing the hemp seed oil and diclofenac gel groups. Heel-to-thigh distance decreased significantly within all groups during the study. There were no significant differences in improvements in heel-to-thigh distance comparing the three groups.

Conclusion, and clinical implications: Hemp seed oil led to greater improvements in VAS pain score and WOMAC parameters, but not knee flexion range, compared to placebo. There were no differences in measured outcomes comparing hemp seed oil and diclofenac gel.