My mom called me late last night. My grandmother was in Princeton hospital in Birmingham for the night for observation after trying to stand on her head - without the use of her hands.
No, not on purpose. She was at the top of a set of steps, next to a flower bed, and bent over to get something off the ground. Unfortunately, she kept going, right on her head.

When she did it, she slammed her chin into her chest.
She
broke her sternum. With her
chin.
Owie, owie, owie!
Unfortunately, my grandmother is very stubborn and refuses to wear her medical call-button thing that's tied in with her alarm company. So she lay out there for who knows how long, hollering for help.

Luckily, a neighbor across the street came home and managed to hear her. But wouldn't you know it, practically the first words out of her mouth were, "Don't call an ambulance."

The neighbor's mother had more sense than that, and told him to go inside and call 911 right away.
There's not really much they can do for it, I don't think they're even going to tape her or put her in a brace like you might do for ribs. She's lucky that's all it is, though - she has bad osteoporosis and what they call a "dowager's hump" on her upper back, and a snapping, pulling injury like that often results in spinal compression fractures or worse. Nada. Just the sternum.
I can barely touch that curved bone in the middle of your collar bones with my chin. How did she manage to break her sternum?!