Read Ana Forrest's response:
I have struggled with wrist pain for many years, and I have learned that it is opening the hands and making space in the hand bones and wrist bones that strengthens and heals this vital area. Students need to learn to spread the fingers and bones in the back of the hands, as well as across the palm. This means spreading the palm, from the little finger to the thumb, as wide as possible. Massage the hand to help flatten the palm and create space in the bones.
Your students can also do a lot of arm strengthening that doesn't put weight on the wrists. Dolphin Pose, Dolphin Pose with elbows at the wall, and Forearm Balance are all good poses for this. Emphasize pushing down on the balls of the hand (the metacarpals) and the inner wrist.
Students can do Downward Dog eventually if they settle their weight in the heels of the feet so that the angle of the wrist is flatter. Put padding under the heel of the hand to help get space in the metacarpals; the pads of the thumbs must remain flat. When working with wrist injuries or very weak wrists, use wrist braces any time there is going to be a weight-bearing practice.