How Do Bones Heal?

The human bone is so strong it's a wonder it ever does break! Bone can carry a load 30 times greater than brick can. The strongest bone in the body, the shin bone, can support a load of 1,600 kilograms.

Yet, as we all know, bone sometimes breaks as a result of violence. Each type of break has a name, depending on how the bone has been broken. If a bone is just cracked with part of the shaft broken and the remainder bent, it is called an "infraction". If there is a complete break it is called a "simple fracture". If the bone is broken into more than two pieces, it is a "com-minute fracture". And if the pieces pierce the muscle and the skin, it is a "compound fracture".

Mending a broken bone is somewhat like mending a broken saucer. The fragments have to be brought into as close alignment as possible. But the big difference is that the doctor does not have to apply any glue. This is produced by connective tissue cells of the bone itself.
Bone tissue has an amazing ability to rebuild itself. When bone is broken, bone and soft tissues around the break are torn and injured. Some of the injured tissue dies. The whole area containing the bone ends and the soft tissue is bound together by clotted blood and lymph.

Just a few hours after the break, young connective tissue cells begin to appear in this clot as the first step in repairing the fracture. These cells multiply quickly and become filled with calcium. Within 72 to 96 hours after the break, this mass of cells forms a tissue which unites the ends of the bones!

More calcium is deposited in this newly formed tissue. And this calcium eventually helps form hard bone that develops into normal bone over a period of months.

A plaster cast is usually applied to the broken limb in order to immobilize the bone and keep the broken edges in perfect alignment.

Strictly speaking bones are healing all the time because they are constantly being renewed. Cells known as osteoclasts drill microscopic holes, tunnels, in bone. Then other cells known as osteoblasts lay down new bone in the holes created by the osteoclasts. In this way a broken bone is said to 'knit' together, though the bone is just doing what it does anyway.

Bones are tough but tough things can also break. Bones break when subjected to immense pressure and stress. Breaking of bones is known as fracture. Now there are various types of fracture, a thin crack in a bone is known as a hair line fracture, a bone can also snap into two pieces like a broken twig. The various kinds of fractures are:
• Complete fracture
• Greenstick fracture
• Single fracture
• Comminuted
• Bowing fracture,
• Open fracture

Now the questions is that how do bones heal once they are broken? Well our bones are natural healers. When a bone breaks, a blood clot is formed and inflammatory cells rush to destroy, invaders and injured tissue. The bone creates a patch called bone callus that replaces the blood clot and holds the bone together. Meanwhile new cells and tiny blood vessels called capillaries are formed that help to rebuild the bone. Initially new tissues bond the bone with a soft callus but after a month the soft callus is replaced by a hard one. During this period of a month remodelling of the bone takes place which then restores the inner canal. Complete restoration of the bone can take up a full year.