How Do Bones Heal?
It all started in Valdez, Alaska, where I was employed as a deckhand on a salmon fishing boat...
Taking advantage of a long-awaited day off -- I had spent the entire previous day rocking back and forth on the boat -- I decided to sleep in. When I awoke I hopped on my bike and headed around to the other side of Valdez harbor to have a shower at a fish processing plant that purchased the fish we caught. With the exhaustion -- and salmon scales -- of the previous day washed away, I climbed back aboard my bike feeling fresh.
Crisp Alaskan air swept by as a grocery bag filled with my towel and dirty clothes swayed gently from my handlebars. As I peddled, I felt a click. “My gears,” I thought, looking down to investigate.
BOOM!
It felt like someone had shot me. Still standing upright I had somehow come to an abrupt stop. I could barely breathe and I had no idea what happened. As the pain began to flood in, my mistake became obvious…
Because Valdez receives an average of over 25 feet of snow each year, the town’s fire hydrants are extra tall, and I had come in full-contact with one.
The stilted steel spout grazed my head and crashed across my left shoulder, stopping me dead in my tracks. If I had been riding three inches farther to the left, the center of my helmetless head would have smashed straight into the hydrant.
Three inches to the left and I probably wouldn’t be here to type this.
Instead, the entire force of the collision was taken by the center of my left collarbone. The bone snapped like thin fishing line, but thankful didn’t splinter and go deeper, where it could have poked holes in the lung below.
I like to say that, at that time, I had three collarbones: two broken pieces on the left and one intact on the right. Like my collarbones, there were three steps in the process of making my two left collarbones one again. Thanks to that three-step process, which I’ll explain below, my arm works a lot better now.
Let us venture away from the cold steel of the hydrant and below my skin, through fatty layers and muscle, all the way down to the bone, where armies of cells in my body, which are there to respond to any incoming problems, began working to stabilize the situation.
Imagine the process of building a bridge across a river...
When my bone broke, it is likely that several little blood vessels also broke. As a result, blood filled up the space between the broken bone, pressing into the muscles and tendons that are right next to the bone. My body had to build a bridge between the bones, across the river of blood that flowed between.
During the first stage of building a bridge, the river bottom is stabilized and the banks are cleared. Similarly, cells from my body’s immune system -- along with builder cells known as fibroblasts (because they make fibers) -- entered the site of the broken bone, repairing the jagged surface so it could be built upon.
The second stage of building a bridge between my bones involved the construction of temporary scaffolding. The fibroblasts that came in during the first stage were now responsible for producing a building material called collagen, which acts as a temporary scaffolding between the bones. Collagen -- similar wooden structures that bridge architects first install in the river -- is flexible and rather weak, but serves a vital role in initially bridging the gap. With the collagen in place my bone was well on its way to being fixed. If I were a regular tobacco user, however there may have been trouble up-river.
Imagine a cluster of giant logs floating down on the river’s current. As a tobacco user’s body works to heal the bone these logs often flow in, knocking out the piers that their cells are scrambling to install. You see, while the bones of smokers or other tobacco users are trying to heal, Nicotine interferes with the body’s natural ability to build with collagen. This is why tobacco users sometimes have difficulty healing from broken bones. Thankfully, I did not fall into this category.
As time passed, the collagen fibers connecting my bone were replaced by bone material, which is analogous to the temporary wooden bridge being paved. There was now a solid connection between the two previously-divided pieces and the bone began to be functional again. It hadn’t, however, reached its maximum strength just yet. First, remodeling needed to occur in the third and final stage.
In bridge building, engineers will test the bridge (hopefully not to the point of collapse!) and will suggest certain areas to be strengthened, adding support structures to high-stress areas. In the body, adjustments are made to the bone structure as cells that live within your bone work on the temporary bridge of bone to make it stronger.
As I began using my bone again and adding stress to certain areas, my body strengthened the parts of the new bone that experienced high-stress. By gradually increasing the force I exerted on my healing bone (without breaking it again!), my collarbone became fully-functional again.
A broken bone can be a life-changing experience, and I’ve been unlucky enough to go through the experience three times, always my own fault! If you were to take any other item, such as a baseball bat or a pencil, and break it like I broke my collarbone it would forever be two pieces. Thankfully, our bodies have a really cool built-in bone healing process, and I’ve been blessed to go through that process three times as well. Bones have the amazing ability to heal, so be patient and let all your little cells build that bridge!
John Scott
Osteopathic Medical Student - 2nd Year (OMS II)
College of Osteopathic Medicine
Pacific Northwest University of Health Sciences