After a surgical removal of the sack, they opened it up and saw that it was full of anatomical refuse, like bone fragments and ligaments. With that said, my
actual left thumb was crooked, and it has been crooked my whole life. The proximal joint can bend too much with ease, all the way down to my palm, and it's very unstable and wobbly. The distal joint is where the crooked bend is at, and it cant bend enough. There's a sensitive lump of scar tissue where the sack was.