I don't have arthitis and don't know much about it other than how swollen and twisted peoples hands can get. I know there's a lot of difficulty in opening child-proof caps, so I wanted to offer up a tip I hope will help. For those of you who may have difficulty with the caps that require you to push down while twisting, the pushing part really isn't necessary. You just have to make sure that the edges of the safety seal aren't hanging over the edge of the bottle to get in the way of the cap. You can have someone else remove the safety seal entirely or if you just push through it rather than remove it, pull the edges up around the bottle to get them out of the way. Once the seal won't interfere, it's easier to open the bottle without a pushing down. Just pull up a little while you twist the cap in the direction needed to open it, and it should just pop right off. They're not really child-proof. The first time may be a little harder to get it off, but after that a slight lift while twisting should get that lid right off for you. I hope that helps some of you.
Thanks for that tip.
My worst problem seems to be with the toilet cleaners, where one has to put thumb and finger either side of the cab and squeeze, then turn. I usually end up getting out the old-fashioned jar openers, using the small section and squeezing - or else some nut crackers.
Lorraine