Bone Healing: What’s So Bad About Moving a Broken Bone?by James Hubbard, MD, MPH

If you’ve only ever seen a dried-up old bone on a skeleton, you’ve gotten the wrong idea about bones. Bones are very dynamic, and that fact impacts how we treat broken ones.

Last week, I wrote that it’s important to immobilize most fractures. Splint them, and don’t walk on them. (Make a cane or crutches if you have to travel for safety or to get help.) But learning why this immobilization is so important will help you remember to do it.

The reasons are multifold. Initially, if you do use the broken bone, besides increasing the pain, you may move the bone further out of place. You’re certainly likely to injure the soft tissue around the bone more. You could make a little crack into a larger break.

But for the long term, if you just keep moving it without a good splint or cast, it’s not going to heal well.

How a Bone Heals

Those dynamic bones in your body are all covered with a thin, fibrous tissue called a periosteum. For one thing, this lining is full of blood vessels and nerves. For another, it contains specialized cells, called osteoclasts, that are constantly eating away tiny portions of old bone, weak spots, or tiny cracks. Osteoblast cells then come in and lay down new tissue that eventually calcifies.

Since a traumatic break is always going to damage the periosteum, the first thing that happens is minor bleeding,* then a clot. The clot is replaced with fibrous tissue called a callus. The osteoblasts come in and replace the callus with calcium.

In order for all of this to work the best, the fracture needs to stay still. Moving will break up the mending, and if the moving continues, the mending may never happen—the bone may not heal. Or if it does, the moving may cause the callus to be much larger, resulting in a big ol’ knot around the break.

What about displaced fractures—those crooked breaks that seem like they have to be moved in order to heal correctly? Check last week’s post for more on them.

Have you ever had to deal with a broken bone with no doctor? What did you do?

 

*The broken bone could also injure one of the big blood vessels. That’s different. With this minor periosteum bleeding, you won’t notice it.