What to do for pain from a sternum broken in a car accident?
Do what open heart surgery patients do. Get her a pillow about half the size of a normal bed pillow and have her experiment with clutching it to her chest. The wrapping of her arms around the area will help stabilize the sternum and help reduce stress put on it. It will be invaluable if she has to caugh or sneeze as well. When my husband was released from the hospital with staples holding the pieces of his sternum together they actually issued him a heart-shaped pillow precisely for that use. He also discovered that he was much more comfortable in a recliner than in a bed. Remind her not to lift heavy stuff for at least a year – it can take that long to heal. And hopefully the doctors gave her drugs – remind her not to drive while taking them.