Final answer:
The nurse should ask the client to maintain the Sims' position to administer the enema solution.
Step-by-step explanation:
To administer an enema solution to an arthritic client, the nurse should ask the client to maintain the Sims' position. In the Sims' position, the client lies on their left side with the left leg slightly bent and the right leg flexed at a right angle. This position allows for easier insertion of the enema tube and helps facilitate the flow of the solution into the rectum.