I second the vote for continental. It’s much easier on my arthritic body (and it’s been that way since I was 14!)
Also, check your overall posture. My most comfortable position is kicked back in a chair with my feet up and my elbows supported either on pillows or chair arms. My right shoulder got threatenmed with replacement years ago, but it’s still working so far and doesn’t bother me if I avoid awkward positions, too much tension or holding heavy projects on straight needles. Another thing–if you’re working on an afghan, big shawl, large sweater, etc., use circulars and let the weight fall on your lap rather than trying to hold it up because that HURTS.