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What Is Bone Remodeling?

Bone remodeling helps heal injured bones.
Osteoclasts are cells that break down old bone cells to make way for osteoblasts to stimulate new bone growth.
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  • Written By: Dulce Corazon
  • Edited By: C. Wilborn
  • Last Modified Date: 16 December 2014
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Bone remodeling is a continuous process of bone resorption and formation for the purpose of maintaining normal bone mass. Normal bone mass indicates healthy bones that are strong and free from problems like osteoporosis. This process goes on inside the human body as long as the person is living. Cells that play important roles in it are osteoclasts, which are responsible for bone resorption; osteoblasts, which are vital in the formation of bones; and osteocytes, which send the signals that bones are being exposed to stress or injury.

Constant remodeling allows bones to perform their many functions, including structural support to the whole body and important storage sites of calcium. With bone remodeling, the body is also able to repair small bone fractures that occur from daily physical activities. Old bone is being replaced by new bone during the remodeling cycle. In adults, this occurs at a rate of about 10% each year. This is a natural process to ensure maintenance of normal bone mass as a person ages.

The remodeling cycle usually starts when injury or mechanical stresses occur in bones. Growth hormones stimulate the production of osteoclasts, which then release enzymes capable of dissolving the bone matrix, creating pits in most bone surfaces. Their lifespan is approximately two weeks, and then they die naturally through a programmed process of cell death, or apoptosis.

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Osteoblasts are stimulated by growth hormones as well. They are responsible for filling the pits created by osteoclasts in bone surfaces. As the bone matrix thickens, osteoblasts incorporate minerals such as calcium and phosphorus into the bone in a process known as mineralization. After their lifespan of about three months, most mature into osteocytes, which reside mostly in the bone matrix and are the ones that give signals of mechanical stress and injury to growth hormones. Other osteoblasts become lining cells in the bone surfaces and are responsible for the release of calcium into the blood stream, while still others die naturally.

The actions of osteoclasts, osteoblasts, and osteocytes are regulated by prohormones and hormones inside the body. These include vitamin D, parathyroid hormone (PTH), calcitonin, testosterone, and estrogen. Any derangement in the actions of these chemicals can lead to certain medical conditions. For example, some studies indicate estrogen deficiency in menopausal women can cause a delay in cell death of most osteoclasts, thus exposing bones to their enzymatic actions longer and promoting osteoporosis.

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galen84basc
Post 3

What are some conditions that could lead to poor bone remodelling? Aside from aging or a vitamin/mineral deficiency, that is.

pharmchick78
Post 2

Great explanation of how osteoporosis and bone remodeling are connected -- so many people are unaware of how important bone remodeling is.

As you said, bone remodeling is critical in maintaining bone health, and is actually connected to your overall health and quality of life as well.

If you're still skeptical, just watch one of those bone remodeling animations online -- that will really clear up the process for you (especially if you're a visual learner like me), and most also have a detailed list of all the benefits that proper bone modeling and remodeling can bring to your body.

Very well written article -- truly enjoyed it.

rallenwriter
Post 1

What are some good ways to maintain bone health? I'm just in my 20s, but I am crazy paranoid about losing my bone structure -- I'm super clumsy, and I can only imagine what would happen if I fall as much when I'm older as I do now.

I know that calcium can keep your compact bone strong, but what about the spongy bone? Is there any way that I can help the bone remodeling units in that area work?

I'd appreciate any advice. Thanks!

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