I have read the same thing as Doz. They apparently considered the wrist as part of the hand.
HOWEVER--it has always been my thought that the Romans knew the actual palm was weak about bearing weight and I figure they roped the arms to the cross so the hand wouldn't bear it after all.
They hung the person in such a manner that they could not breathe without pushing down with their legs. They had to push their bodies up for every breath. That is why they broke the thieves legs--so they would suffocate and die.
Good question. It may have been in the wrist, or they may have roped up the arms. We will learn when we see Him face to face!