| I'm not aware that any such stand exists. You don't give us much to work with here. If you can answer some of the questions below, we might be able to suggest some solutions.
1. How does your arthritis affect playing the bass? Does the problem involve your fingers? wrists? elbows? shoulders? spine? Is it a question of stamina?
2. Are you mostly a pizz. or arco player?
3. What size of bass do you play?
4. Do you have a teacher?
Some possible solutions may entail one or more of the following:
1. Revising your playing position.
2. Getting a smaller or more ergonomic bass.
3. Doing some exercises to increase flexibility and endurance.
4. Obtaining an evaluation from a medical professional specializing in the physical problems of musicians.
I have some significant spine problems that I need to work with, but what works for me may not do the job for you. I'm sure that some folks here can provide information that will help all of us.
Good luck to you. | 
