system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: In old movies/photos people with their legs in a cast have their broken legs hanging high in the air comically. Why?

In old childrens books and movies I see injured people with their casts tied to a giant structure such that their leg is practically straight up. What is going on here? Is it still done now commonly?
gpt
On Femur breaks, the thigh muscles are so strong that they have to pull on the leg and stretch it back out, to line the bones back up. That is called traction. However on Tibia and or Fibula breaks the swelling against the cast causes a lot of pain. Elevating the leg reduces the swelling reducing the pain and prevents the cast from cutting off the circulation because of swelling.