have you looked into the medical profession. See if there are any types of documented physical therapy that helps with your specific condition.
I'm having a bit of trouble picturing exactly what your situation is.
is it that you have problems straightening your fingers even? Is it a strain to simply hold a straight palm?
If so there may be people who have studied and worked with others in your situation.
For whoso comes amongst many shall one day find that no one man is by so far the mightiest of all.