I agree that that is a valid question, one I have asked before. The only two aspects I can think of are these:
1. The regular method for finishing the execution were to break the bones of the condemned person's legs with an iron bar. This caused death by asphyxiation, due to the pressure of hanging for hours by his arms, which only allowed him to exhale. He would push up with his legs to be able to take a breath. Jesus, because of the rush to take the prisoners down (Passover), was pierced with a spear instead.
2. I don't know how often prisoners were forced to wear a crown of thorns, but I suspect that this was rare.
The shroud exhibits both of these events. Those aren't conclusive observations, but I think they limit the possibilities.
Good points M.Thanks for the response.From what i've read the wounds present on the shroud do correlate with the wounds suffered by Jesus.But will we ever know for sure the impression of is Jesus?Maybe a little mystery won't hurt?A "Doubting Thomas"