ccWe get asked this question all the time in clinic as people find it super interesting. Obviously, it’s complex but we’ve made it a little more simplified, so we don’t get bogged down in minor cellular details. So, here’s the simplified overview.
Your bone has a skin, yes, it is slightly gross but its also completely normal. When you break a bone the skin on the bone rips as well. This releases lots of bone growing cells into the area. These little cells start building up new bone around the area of the break, but that takes time. There’s lots of blood in bones, as bones are alive and need blood to survive.
Day 1-5
The bone breaks and the bloods vessels supplying the bones rips and you’ll often see a swelling initially, followed by dark purple bruises over the coming days. A collection of blood clots form like a big scab around the fracture site. This forms a weak temporary framework for the healing that’s to come next.
Callus Formation (Days 5 to 11)
Within the hematoma (scabby bit), new tissue begins to develop. Stem cells brought to the area to help repair start to grow into different types of workers for the repair job. So we’ll see stem cells turning into one of the following: fibroblasts (build strong fibrous webbing made of collagen), chondroblasts (build cartilage), and osteoblasts (build bone cells). These cells work together like a bunch of builders to create a collagen-rich fibrocartilaginous Callus to hold the ends of the fracture together. This tends to be thicker than the original bone, so you often see a lump where the fracture/break was.
Boney Callus Formation (Days 11 to 28)
The cartilaginous callus which has just been built is ok but it’s not as strong as normal bone. Your body will start to absorb the callus and lay down more bone formation. By the end of this stage if everything is gone well you have a nice bony callus.
Re-modelling (Day 18 onwards, lasting months to years)
This hard callus undergoes continual re-modelling, where it’s getting absorbed slowly and built up better.
So that’s what happens when all goes well. Fracture healing is influenced by lots of things including how good the blood supply to that area is, if you move the fracture too much it often wont heal or takes a very long time. Or a local infection can get in the way of it doing its normal recovery.
Smoking and Alcohol Intake
Smoking an alcohol make a huge difference to bone healing. Unfortunately, people often have a bone break, they’re of work and they don’t have much to do and think, I’ll have some glasses of wine and they end up off their feet for weeks longer than they need to be as they’ve increased the healing time.
Other factors
- Age
- Obesity
- Diabetes
- Steroid use/abuse
- Nutrition and Malnutrition
How long does it take for your bones to heal?
Most fractures heal in 6-8 weeks, but this varies tremendously from bone to bone and in each person based on many of the factors discussed above. Hand and wrist fractures often heal in 4-6 weeks whereas a tibia fracture may take 20 weeks or more.
Hopefully you know a little bit more about bone healing and why it takes so long and why you shouldn’t do too much too soon, and what to avoid doing so you’re not slowing down your recovery. If you have sustained a bone injury, the most important thing is to listen to your healthcare provider and follow their advice so that you have a successful outcome and can get back to doing the things you love.
