How do you brake your leg by falling off a 10 foot wall?

Easily, especially if the surface below is concrete or solid granite. Also, the saying, the bigger you are, the harder you fall has a lot of truth. A horse can fall a very short distance, a mouse can fall a hundred feet sometimes without injury. Older people can get broken bones more easily than young ones, because their bones essentially get brittle. A smart person would hang from their hands off a 10' wall before falling, making it a shorter fall, maybe only 4 feet. Or fall onto softer material. Or fall onto downward sloping hill, to allow a rolling impact. Falling straight down without any rolling while hitting solid ground, can be quite dangerous, although the guys on TV make it look easy. They use a number of tricks, including giant airbags, hidden foam padding etc. If one breaks vertebrae or hits their head, even fairly short falls can be deadly or crippling. I had a friend who as a little kid, broke his leg falling off a fence only about 5 or 6 feet tall. It was made of concrete blocks. They didn't cap the top, so the openings in the block were still open. Walking along the top, a leg fell into a hole part way and his body fell over the edge. He had to dangle there, with the middle of his leg bent like a " ^" until someone helped him down. That's another way... I slid off a roof, maybe 9' tall, while standing on a plastic solar collector when I was almost 30. Luckily, I jumped sideways onto a pile of wood shingles below, and was rather shaken up. As it turns out, I should have gone home for the day after that, but that's another story. [the original question was "How do you brake your leg by falling of a 10 foot wall" SIC]