Boswellia (a.k.a. Frankincense) has been used to treat arthritic pain and inflammation for thousands of years. Modern clinical studies have found that this effect is primarily from the inhibition of 5-lipoxygenase, which is different from typical anti-inflammatory drugs like Ibuprofen or Aspirin. The effectiveness of Boswellia for osteoarthritis has been demonstrated in clinical studies.
Boswellia in the treatment of Osteoarthritis:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2575633/
Boswellia in Chronic Inflammatory Diseases:
https://www.ncbi.nlm.nih.gov/pubmed/17024588
https://www.thieme-connect.com/products/ejournals/pdf/10.1055/s-2006-947227.pdf
Boswellia, An Overview:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3309643/