Achy breaky stroke hand

On one of my long driving trips I managed to get my affected hand open and spread on top of my left leg. Normally the thumb loses its position soon and the whole arm falls into the abyss between the seat and the door. Then I have to hope like hell I never get T-boned on that side because I can't lift the arm out without using my right hand. This particular time it stayed there for about an hour. By which time the thumb muscles were very painful. It is completely disgusting that 12 years after my stroke spasticity still prevents my recovery.  Don't suggest botox or muscle relaxants, they don't do anything for recovery.