Possible to fix thin fingers that can't straighten out? (photos)

I have thin fingers that's sort of "tapered" where the base of the fingers are a lot thicker than the tip. I also can't straighten the fingers all the way. This is most prominent on the index and pinky fingers on both hands. I don't think it's dupuytren's because I can open and close the hands fine. Maybe the skeleton or joints in the fingers. Is it possible to transplant fat to the fingers to make them thicker and more "linear"? And if possible, straighten them out? Thank you for answers

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