I do private sessions with a student who has some issues with arthritis, so I've been doing some research on the subject. I found this interesting video, posted by John Hopkins Rheumatology, that has a bit of information about how yoga helps arthritis. It includes some modifications for people with arthritis as well as for those who have trouble coming down onto the ground, issues with the wrists, knees, or other joint issues.

Some of this is similar to some things I teach in my videos, but it's certainly worth a watch if you have joint or mobility issues. The evidence seems clear (from a number of studies) that yoga does indeed help with arthritis.