Children are not just simply smaller adults. Their major organs such as heart, lungs, liver and kidneys are developing and so the function of these organs differs from adult organs. Kids’ bones are also growing. What this means is that they are not as brittle as our bones.
If a child falls out of tree, he or she might not have any major broken bones. Why? The bones are softer and the energy of impact might cause the bones to crack slightly-similar to a green stick cracking (which is why such fractures are called green stick fractures). Only the covering of the bone-or periosteum is cracked, leaving the central part of the bone unharmed. Not only that, but the bone will heal faster, as children are growing anyways, so the process of healing is already accelerated.
On the other hand, an adult who fell out of a tree (you might want to kn0w why for God’s sake was an adult of reasonable mind up a tree, but that’s another story) would be much more likely to break several bones. Ironically however, the adult might break more bones but suffer less internal injury than a child. This is because the broken bones absorb some of the force, leaving less force, so to speak, to cause internal injuries.
In adults the bones have stopped growing and those areas in the bone where growth occurred (growth plates) have fused. If a fracture involves an adult growth plate, it does not cause any special problems other than the broken bone, of course.
Kids’ growth plates are active and open. A fracture or break through a growth plate has the potential of stopping growth permanently. Left alone, this can cause shortening of the involved limb. Practically, these means that treating doctors must be very careful to determine whether or not the break is within the growth plates. Such fractures require orthopedic consultation and sometimes surgery.
Still, even with the growth plate problem, kids fare overall better when it comes to broken bones. Oh and by the way, they also don’t have to explain to friends, what they were doing up that tree.