Jean Hilliard’s frostbite, while significant enough to produce blistering of the toes, did not penetrate deeply enough to require amputation.

The fact that she retained all her digits after six hours at 22 below zero is itself remarkable — many severe frostbite cases require amputation of fingers and toes even after much shorter exposures.

The protection of her deeper tissues may reflect the vasoconstriction that had redirected blood away from the periphery but had still maintained a very slow trickle of warm blood that prevented the deepest freezing.

Or it may reflect the specific thermal properties of the tissues — the rate at which heat is lost from tissue varies with depth, and the innermost tissues of the toes may have remained above the freezing point while the outermost layers froze.