How do bones know which ones should grow togher

Question

I just broke my hand and the doc said it’ll grow back together by itself. Why does the broken part only grow to the correct bone and not to a random neighboring bone. Why don’t other bones grow together when they touch in a joint?

In: Biology

Answer 1

DNA knows what to do. It knows not to fuse a joint, though arthritis and other diseases are problems. DNA has a blueprint of the broken bone, and knows where to fill in missing bits with new bone.