The latest research using cadavers shows that each nail in the palm COULD actually support better than 60% of the body's weight. Given that the feet were also nailed, the likelyhood of pulling through the palm is small.
However, a professional executioner would not want even that small a chance of error. There is, however a solution that is much more logical than the nail through the wrist.
The original work done by Dr. Pierre Barbet concluded that the nails could only have gone through the wrists, specifically through the Space of Destot, is wrong. He used cadavers that had been dead for some time and suspended the body's entire weight on one hand.
It was Barbet who proposed the "nail through the wrist" scenario because the wrist wound seen on the Shroud of Turin showed an exit in the back of the wrist. Barbet erroneously claimed that the Space of Destot is only one pathway through the carpals that would allow the nail to penetrate without breaking a bone. One slight problem... the Space of Destot would not have a nail exit the wrist where the wound on the Shroud shows it. He claimed also that the proof of his hypothesis was the lack of thumb images on the Shroud, explaining that a nail driven through the Space of Destot would strike or sever the median nerve, paralyzing the thumbs and forcing them to curl into the palms. Another small problem: the median nerve is nowhere near the Space of Destot and a nail driven there would not come close to doing what Barbet hypothesized.
Dr. Frederick T. Zugibe, M.S., M.D., Ph.D., FCAP, FACC, FAAFS, has proposed another method that meets both the iconographic, traditional palm placement of the nail entry wound, the exit wound shown on the Shroud of Turin, and the strength of the wrist bones needed to keep the crucified pinned to the cross.
This alternative pathway actually starts IN THE PALM and exits exactly where the wrist wound is located on the image on the Shroud of Turin. The starting place on the palm for this pathway is really easy to find: hold your palm facing your face and fold your thumb toward the center of your palm. This forms a valley . Place your finger at the base of the valley and you'll feel an indentation. Place a nail point there and drive it in angled toward the back of the wrist (about 45 degrees) and it will slide through the carpals and exit in the back of the wrist, exactly where the wound is shown on the Shroud.
This nailing position actually makes it EASIER for the nail driver to accurately nail through the tough bones of the hand and wrist. If the executioner lays the intended victim on the ground the hand falls naturally into this position if the elbow is on the ground and the back of the hand is pressed backwards onto a patibulum that is several inches thick... the angle of driving the nail is then perfectly straight, perpendicular to the wood. Expert crucifixionists would know of this and use it.
Incidentally, Dr. Zugibe, through the use of volunteer LIVING subjects, has proven that crucifiction does not kill through asphyxiation as has been long thought (again, due to the work of Pierre Barbet) but rather by hypovolemic and traumatic shock.
There is another picture of thumb side of a cadaver's hand with a very large needle inserted through this space and it exits exactly where the wound on the Shroud shows it did. I have not posted it because it is very graphic and is not suitable for a family site.
The entire peer reviewed paper is available here e-Forensicmedicine.net