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

Question

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