Once I've been crucified and my cross raised, I wouldn't want to be rescued. I'd rather die than live with paralyzed hands anyway...
That is a big consideration all right. In a Roman crucifixion using nails through the wrists and feet, and considering the size of the nails used, there could be permanent damage.
I did some calculations years ago based on the material properties of a wrought iron Roman nail and figured out that to carry the stresses from a 150 pound victim, the nails would need to be about 0.35 inches square at the point where they entered the wood. Since Roman nails were tapered, the part that passed through the wrists or feet would have been larger, maybe as big as 0.4 inches square where they passed through or between bones. This is a minimum; I doubt that Roman executioners gave a lot of thought to that, just used nails that were at least "big enough" to do the job.
Here's an X-ray of a human foot with a square Roman nail cross-section superimposed:
The blue circle is an approximation of the size of a nail head proportional to a Roman nail of that size. The scale is based on the size of my own foot, which is a US size 13, so for most people the nail would be bigger relative to the foot and the space available for it to pass through. I think a nail driven like that would either break one or both of the bones adjacent to it or tear the ligaments at the joints above and spread them apart.
Here's the same size nail superimposed on a wrist:
There's no guarantee that an executioner would get the nail precisely as I've shown it, but that seems to be the likely location, what some refer to as the "hollow spot" just where the "lifeline" of your palm ends. A nail driven there would either break one or more of the small bones or else tear the ligaments apart between them and spread them, which I think is more likely. It would be difficult to miss the Median Nerve as this is very close to the Carpal Tunnel, so yes, you'd have permanent nerve damage and some paralysis of fingers, but I doubt that you'd lose the entire use of your hand.
As I think about how you'd have rescued a crucifixion victim nailed to a cross in a public place back in Roman times, it seems really unlikely that anyone would have been successful in pulling that off. Probably "rescue" meant somehow getting to them long enough to slip a knife under their ribs and end their suffering.