How do broken bones heal?

Bank Khamtonwong

I’m sure many of you will have broken a bone at some point in your lives, or if you’re accident prone like me you’ll have broken several! Whether it’s from a rough fall or maybe getting crunched in rugby, we can all appreciate that whatever the method breaking a bone hurts. But how is it that these broken bones repair themselves and what measures are taken to ensure they heal properly?


The bone healing process

Upon being alerted about a fracture (technical term for a broken bone), the body will spring into action to immediately start the healing process. Firstly, a blood clot known as a haematoma will form around the site of the break in order to protect the bone and deliver the cells needed for repair. Happening alongside this the immune system will also kick in, pumping extra blood to the fracture site which will send in white blood cells to kill any bacteria around the bone – this extra blood flow explains why the body part with the fracture will normally become very red and swollen following the injury.


Next, a type of bone called a soft callus will start to form, slowly replacing the haematoma over the coming weeks around the fracture. At this point however, the soft callus will be too soft and won’t be strong enough to withstand the pressures that bones can experience on a daily basis until it eventually hardens. While the hardened callus will be strong enough for the body part to be used, it still isn’t as strong as normal bone and so the healing process is still not over.


Around 3-4 weeks after the initial fracture, the final stage will begin where regular bone will form and slowly replace the hard callus. This is done by very specialised cells known as osteoblasts and osteoclasts. Osteoblasts work to form and to lay down the new bone in conjunction with the osteoclasts which are responsible for resorbing the callus. As the bone is being repaired, it is constantly being reshaped to what it looked like before to ensure the bone doesn’t heal unevenly – this process is known as bone remodeling. This stage is the longest where, depending on the size and location of the fracture, it can range from weeks to even several months for the bone to fully heal!


What can be done to help bones heal better and faster?

As the bone healing process is so effective, most treatments for a fracture involve allowing the body to heal itself while nudging it in the right direction. This is most commonly done by using a cast or a splint on the broken body part. These are support devices made of hard material that prevents the body part from moving around so that the bone fragments are not disturbed during the healing process. This is quite important because bones may heal incorrectly or entirely in the wrong position. In some special cases, when the fracture is severe for example, a surgeon may decide that a cast or splint is not enough and that the bone may need screws, plates, or wires as well to hold it in place.


Nutrition is also an important factor to consider when healing a broken bone. Foods high in calcium and vitamin D will be particularly crucial as these nutrients are essential for bone health. These foods will include many dairy product, leafy green vegetables, and fatty fish.


Gentle exercises are also advised to promote faster healing. This is known as physical therapy where a physiotherapist will create a program specific to the patient’s injury. These exercises will help keep the blood flowing to the injury site while increasing your strength and range of motion while in the cast. Very importantly, physiotherapists will help their patients learn how to live and move safely while their bone is healing so that they don’t reinjure themselves, for example, this can involve teaching the patient to correctly use their crutches while their leg is injured.