How does a broken bone heal?

Bone tissue is four times as strong as concrete. And yet an accident can happen just around the corner. Before you know it, you’ll break your arm, your collarbone, or another bone in your body. Adult men and women have about 206 bones. Due to anatomical variations, the precise number of bones may differ. Babies have many more, 350 on average, but as they grow older a number of bones grow together. That explains the difference.

  • Bones
  • Bone structure
  • The longest and smallest bone
  • Bone cells
  • How do bones break?
  • Broken bones or fractures
  • Scars
  • How does a bone heal?
  • What happens if you break a bone?
  • Plaster, splint, brace or bandage
  • Operation
  • Bone implant
  • Regenerative medicine
  • When is a broken bone healed?

 Source: Clker Free Vector Images, PixabaySource: Clker Free Vector Images, Pixabay


The human skeleton consists of bones, also called bones. As an adult you have about 206 bones, a baby has more, about 350, because a number of bones are still growing together. Our skeleton provides support and together with the muscles it ensures that we are protected, can stand upright and move.

Bone structure

Bones are very light. This is because they are not massive, but consist of a huge tunnel system. The inside consists of a spongy material: the bone marrow. In babies, all bones still contain red bone marrow. Blood cells are formed in the bone marrow. This involves enormous production: about 350 million per minute. There are three types: the red ones (which ensure that oxygen is transported through your body), the white ones (involved in fighting diseases) and the platelets (which ensure that the blood clots). From the age of five, yellow bone marrow slowly replaces red bone marrow until it reaches maturity at the age of 20-25 years. Red bone marrow is found in the bones of the trunk and skull in adulthood. Yellow bone marrow is so called because it consists mainly of fat cells and has no known function.

The longest and the smallest bone

The longest bone is the human femur, the bone that runs from the hip to the knee. It occupies more than a quarter of the total body length. The smallest bone is the stapes (so named because of its similarity to the part of the horse harness of the same name), one of the three ossicles in the middle ear. In humans, this tiny bone weighs about 2.5 milligrams. There are different types of bones, depending on their location in the body and their function. But they are all made up of three types of bone cells.

Bone cells

There are three types of bone cells:

  • Osteoblasts, or bone-forming cells
  • Osteoclasts, or bone-breaking cells
  • Osteocytes

Osteoblasts or bone-forming cells build the structure of the bone by ensuring that the mineral calcium phosphate crystallizes in the bone, allowing it to harden (mineralize).The osteoclasts do just the opposite. They dissolve the hardened calcium phosphate crystals again. This way they break off the bone again.The osteocytes are bone cells that start as osteoblasts, but become encapsulated in the tissue during the building of the bone tissue. As osteocytes, they are communication cells that can receive signals and pass them on to other cells. How exactly they communicate is still unknown, but they can ‘talk’ to surrounding osteocytes by developing extensions (canaliculi) that allow them to touch each other. They thus exchange minerals, nutrients and waste products. The total length in humans can be up to 175,000 km. It is therefore the most common bone cell in the human body. Because bone is constantly being built up and broken down and thus formed, the network of osteocytes is constantly in motion.All bone cells communicate with each other. In this way, a bone can be shaped precisely in such a way that its density increases as the pressure and load increases. The reverse also applies. In space there is no air pressure and the weightlessness erodes the bones and makes them porous. It is therefore important to regularly load your bones correctly. They need resistance to function.

How do bones break?

Bones can break due to appropriate force and bone weakness. In the first case, for example, there is a fall or accident. The force and pressure breaks the healthy bone. In the second case, there is osteoporosis (bone decalcification) or tumors or metastases that cause weak parts of the bone. In the latter case, a bone fracture is called a pathological fracture.You know you have broken a bone when you can no longer move the part of the body in question, or there is a lot of pain during movement. If there is deformity or misalignment of the body part or large swelling, these are also indications that a bone has been broken.

Broken bones or fractures

A bone may be completely in half, there may be a crack in the bone, it may be shattered, or there may be a splinter of the bone. You also have open and closed bone fractures. In open fractures, the bone protrudes through the skin. An open wound occurs. This is a complicated fracture. With closed bone fractures, you cannot immediately see from the outside that a bone has been broken. You may see a bruise, a bump or misalignment of a shoulder, foot or wrist, for example. Sometimes this is a simple fracture or a fracture with multiple parts (communive fractures); sometimes it involves a closed bone fracture with undamaged skin.


In principle, your body can repair the damage caused by a broken bone itself. Just as a cut in your skin heals, bone also heals on its own. Provided there is no inflammation, of course, if there is also an open wound. And if the wound is not too big. Just as skin can bear a scar after a wound, bones can also become scarred as they heal. This is the callus formation, a chalky tissue that closes the bone again. But scar tissue forms faster than bone tissue. If scar tissue has already formed, recovery stops. As a result, the body can no longer repair very serious fractures on its own.

How does a bone heal?

Healing of a bone occurs in three phases: the inflammatory phase (two weeks), the recovery phase (six weeks) and the remodeling phase (the first year).

  • A bone fracture causes the veins in the bone to rupture, releasing blood. This blood collects between the broken bone parts.
  • When there are cracks or tears in the bone, the stem cells present there change into osteoblasts. The mesenchymal stem cells produce a type of bone tissue via the incoming blood that attracts calcium phosphate, so that it first becomes flexible and then even harder in the coming months. The veins also reconnect across the fracture.
  • In this way, the connective tissue slowly hardens into cartilage and then becomes bone.
  • After a few months the bone has healed and the fracture has been repaired. The bone around it remains as it was, only the affected part and the new bone tissue becomes hard. The body will now do its best to make the new bone resemble the bone as it was. This is usually easier for children than for adults or the elderly.


What happens if you break a bone?

If it turns out that you have a broken bone or that this is possible, you go to the hospital. There they take an x-ray. This allows the precise location of the fracture and the type of fracture to be determined. Sometimes a CT scan is necessary, also to see what further damage is. The bones are then positioned correctly in relation to each other. Sometimes this is done under local or general anesthesia. By straightening the bones you prevent unnecessary scar tissue and ensure that as little bone tissue as possible is needed to put the bones back together. And, also very important: make sure that the bones grow back together correctly.

Plaster, splint, brace or bandage

To ensure that the bones remain in the same position, you can use a plaster cast, a splint or a brace. This supports the healing process and the bones themselves. This way we prevent unnecessary pain. The bone parts cannot move independently of each other and therefore cannot damage surrounding tissue and nerves.A broken nose is often noticed by pain and misalignment of the nasal bones. If the swelling is too big, it is difficult to see. Then it is necessary to wait until the swelling has subsided somewhat and then straighten the nose. It is best to carry out examination and treatment within five days. Then you know more. The reduction or straightening of the nose must be done within 10 days at the latest, because after five days the bone parts already start to grow together.For broken toes, a good pair of shoes often provides enough support, so that a cast is rarely necessary. Unfortunately, that does not mean that the pain will be over quickly. It can take up to a year before the toe becomes less sensitive to shock and impact. It is very difficult to put a plaster cast on a broken collarbone. That is why a sling, a triangular cloth that provides support, is often sufficient.If plaster is necessary, the surrounding joints are often also wrapped. This can cause stiffness. In any case, there is a decrease in muscle mass because you hardly use the body part. This is also why you are often not allowed to put any weight on the affected body part immediately once it has been removed from the plaster cast. Once you are out of a plaster cast, this can often be resolved quickly with extra practice and exercise.


If the fracture is very serious, plaster is not sufficient and the bones must be joined together with metal wires, pins, plates or screws. This fixation is done during an operation. Sometimes the used parts have to be removed again during a second operation.

Bone implant

Sometimes the bone does not heal properly. Or there is a hole in the bone, for example due to a tumor. A bone implant is then inserted to help the affected part recover. This can be your own bone, for example from the pelvic brim. New bone grows better on old bone. Other possible solutions include 3D printing of bones or bone parts. Sometimes these implants are milled, for example in the case of a partial skull construction. However, these can increasingly also be printed. Even more customization and less waste.

Regenerative medicine

In some cases when the bone does not heal on its own, regenerative medicine may (in the future) offer a solution. Natural bone tissue is simulated in the lab. The aim of regenerative medicine here is not only to replace the old bone, but also to allow the new bone to produce bone tissue itself. Using body’s own material such as mesenchymal stem cells increases the chance of this happening. In the laboratory, the substance Cyclic AMP is added to stem cells. This ensures that they develop into bone cells and that they stimulate each other. Growing bone tissue outside the body is a time-consuming job. It could take months. A practical application of this could be to grow mini bones with the help of which you can test whether certain medications will work or not. Then you will experience the effect of a particular medicine more quickly and therefore have a better and faster chance of determining the best treatment.

When is a broken bone healed?

Properly healing a bone fracture takes time. A lot of time. First there is the pain, but even when it is gone, it still takes a long time before you can move and strain the affected body part as usual. Patience is necessary, because exercising too early and too much is counterproductive and only prolongs the recovery process.On average, the recovery from a bone fracture in the lower half of the body takes twice as long (on average 14-16 weeks) as a bone fracture in the upper half (on average 6-8 weeks). In children, fractures heal on average twice as fast as in adults. And the older you are, the longer it takes for you to fully recover.A bone can heal faster through bone growth stimulation via ultrasound. This is especially suitable for people whose bones heal less quickly, such as smokers and diabetics. The sound waves stimulate calcification in the cells that produce bone. It may only save a few days, but everything is a gain if you can’t move as you would like.