Pain in thumb knuckle when pressing ?

My first advice is to not press knuckle. A;-) Second is ask men in your family as older in u if they have had this and if so what was it. Third go to uptodate.com and real about osteoarthritis then discuss with your team.

If one uses hand intensely/ frequently (especially the thumb to press down on items); one can have 'overuse' syndrome type pain which could be simple strain/tendinitis but Arthritis and other systemic/ Inflammatory disorders can also present with 'pain in the thumb knuckle'. PCP/ Hand Specialist might help clarify cause of pain and its management.