Season 4, Episode 8

Also known as: Mild traumatic brain injury

J.D. sustains a minor concussion during a scooter accident while trying to reach Molly's apartment. Doug examines him and confirms it's minor.

Also known as: Broken collarbone

J.D. fractures his collarbone when attempting to rappel down from a balcony using a hospital gown, resulting in a fall and injury.