What does the irony in these excerpts from “in another country” by ernest hemingway convey?

the doctor came up to the machine where i was sitting and said: "what did you like best to do before the war? did you practice a sport? "

i said: "yes, football."

"good," he said. "you will be able to play football again better than ever."

my knee did not bend and the leg dropped straight from the knee to the ankle without a calf, and the machine was to bend the knee and make it move as riding a tricycle.

. . in the next machine was a major who had a little hand like a baby's. he winked at me when the doctor examined his hand, which was between two leather straps that bounced up and down and flapped the stiff fingers, and said: "and will i too play football, captain-doctor? " he had been a very great fencer, and before the war the greatest fencer in italy.