Sounds almost like DD…. Depuytrens disease. Otherwise known as Viking claw or Celtic hands. Some northern ancestors Ben? Can opening with a p51 might bring it on. I learned about this only recently after watching a documentary called Blood of the Vikings: First Blood. One of my hands had a cramping problem where the only way I could straighten out the fingers was to use my other hand. For a while I was worried I might have DD or arthritis. To early to tell but I did start exercising my hands more.