When the girl on the bike gets knocked over she falls on her left side, she tires to break her fall with her leg and winds up hitting her left knee on the pavement. Yet when Lt. Benson runs up to her the girl is holding her right thigh just above the knee, not her left. With the way she fell there would be nothing wrong with her right knee; however her left knee most likely has a fractured knee cap and a torn ligament.
Stone muses on the Bible verse "suffer the little children to come unto me", and says he is baffled over how children are allowed to suffer. However, "suffer" in this context refers to the word's now archaic definition, which means "allow" or "permit".