Thank you for your question. It's quite uncommon, but fillers can potentially be used in the thumbs to address issues such as volume loss or discomfort due to thin skin. However, this application is not typical and would require careful consideration by a specialist. The use of fillers in the hands, including the thumbs, should be conducted by a board-certified dermatologist or plastic surgeon experienced in hand rejuvenation. They can assess your specific situation, examine the extent of volume loss, and determine whether fillers are a suitable option to alleviate pain and improve functionality. It's important to have a thorough consultation to discuss potential risks, benefits, and alternative treatments that might also be effective in managing your symptoms. I recommend scheduling an appointment with a specialist to explore your options further.