Who fixed knee after he feel from the swing on The Boy in Striped Pajamas?

There's no mention of anyone fixing a knee after a fall from a swing in the book "The Boy in Striped Pajamas." The book focuses on the tragic story of Bruno and Shmuel during the Holocaust, and there are no scenes involving swings or injuries.

It's possible you're thinking of a different book or film. Could you please provide more details about the story you're referring to?