Is an indent in the tenar thumb muscle a sign my basal joint arthritis has worsen? i am always counting down the days to my next cortizone (hydrocortisone) injection

This is likely.: Thumb arthritis is associated with pain, decreased motion, and intermittent swelling. As the condition worsens the ligaments stabilizing the thumb will weaken and the thumb joint will start to deform. The muscle may change in shape due to the changes at the joint. Unfortunately, you can also see the muscle change shape with significant carpal tunnel syndrome but you would have numbness as well.