You know how when infants start to get some strength in those little arms and legs, they sometimes very suddenly push off of you while you’re holding them and lunge away? One of our friends had little experience with babies and he was holding his firstborn the first time she tried this and he started to lose his grip on her. He quickly grasped one of her legs to keep her from falling. He did keep her from hitting the floor, but her leg rotated at an odd angle in the process and it broke. He felt like the biggest a$$hole in the world for breaking his baby’s leg, but everyone understood that this stuff happens.
Another time, I was at a party and a couple left in a hurry after they got a phone call from their parents, who had been babysitting their toddler for them. The grandpa had gone down a slide at the park with their little one on his lap and the toddler’s leg got caught between the outside of his own leg and the slide and had gotten twisted. The child’s leg turned out to be broken and the grandpa was extremely distraught.
My mother always says it’s a wonder any of us survives childhood.