I had severe arthritis during my last flare where my knees hurt to point where it was difficult to climb stairs. Interestingly I could not make a fist either but one day it would be my right hand but the next day the right hand is OK but my left hand would be stiff. However my arthritis disappeared once I got back into remission.
You might have a different problem. My girlfriend had a similar problem of not being able to contract some fingers in her hand. I dunno, perhaps it was Dupuytren's contracture. But she took some of the active form of vitamin B6, pyridoxal 5'-phosphate (P5P), and her stiffness was gone in 3 days.http://www.ncbi.nlm.nih.gov/pmc/articles/pmc347366/?report=abstract
For all patients receiving therapy with pyridoxine, the B-6 deficiency was corrected and the neurological syndrome was alleviated...
"Rheumatic" conditions associated with this syndrome have included "tennis elbow," Dupuytren contracture,
deQuervain disease, "trigger fingers," bursitis, and periarthritis of the shoulder.