Ride with some bend in your elbows. Try to relax your arms and hands more, reduce stiffness and tension. Move your hands to various positions during a ride. You may need to work with your fit on the bike. While it is true that Campy shifters require less pressure for shifting, changing brands is probably not going to make much difference to your arthritis symtoms. Your position on the bike may. I have osteo-arthritis, STI, and Campy Ergo.

Al