If you are going to deny a one legged a wooden leg that very well may be construed as a cruel and unusual punishment. None of the other prisoners have to go without one of their limbs as a consequence of their crime. I think that principle can apply to the OP situation as well.
Why should he have the added burden of not being treated for a serious medical condition? If you say it is because it is a consequence of his crime then I have to point out it is a sentence that he didn't receive in a court of law and that was imposed on him arbitrarily, without recourse to any form of justice.