The Process of Bone Resorption Explained

Updated on July 8, 2019
pandula77 profile image

I am a medical doctor, and I am presently doing my PhD in relation to bio-medical informatics at the University of Oslo, Norway.

Bone resorption is the process of braking down the bones into its mineral and collagenous constituents through a cellular mechanism. The process may be part of the normal regulation of minerals such as Calcium in the blood or it could also be due to a pathological or disease process, which accelerates the rate of bony breakdown. In order to explain the process of bone resorption, first, it is vital to understand the structure of a bone and its cellular constituents.

Structure and Cellular Constituents of a Human Bone

In general, the bones are formed of cells, non-mineral collagenous matrix and mineral deposits. Among the cells present in the bony matrix, some contributes towards the formation and maintenance of the bone while other cells facilitate breakdown of the same. The cells that supports the formation and the maintenance of a bone, includes cells such as ‘osteoblasts’ and ‘osteocytes’. The cell type, which facilitates break down of a bone, is the ‘osteoclasts’.

When looking at the cross section of a bone, the outermost layer is termed as the ‘cortical zone’ while the inner zone of the bone is given the name, ‘trabecular’ or ‘spongy’ zone. Furthermore, the periosteum and endosteum lines the bone surface and the trabacular spaces respectively. These two linings are rather thin and consist of vascular complexes to supply nourishment to the cellular elements.

The matrix of the bone, which is mainly constituted by collagenous material, gains its hardness due to the deposition of mineral salts. Among these minerals, calcium and phosphorus are the most significant and in the living bony tissues, they exist as hydroxyapatite.

The Initiating Factors for Bone Resorption

In a healthy individual, the bone formation takes place until adulthood and thereafter a process known as ‘re-modeling’ will take over. Re-modeling refers to the replacement of ‘old’ bone tissues with new ones. Thus, resorption is an essential part of maintaining required density of a particular bone.

At the same time, the calcium level in the body is also a determining factor on the resorption state of a bone. Thus, when the blood calcium levels decrease, the parathyroid gland in the neck region will detect the same and will initiate the secretion of ‘parathyroid hormone’ (PTH). PTH will accelerate the resorption process in order to replenish the reduced calcium level in blood.

Apart from these factors, certain disease processes such as psoriatic arthritis, lack of stimuli, disuse, and even the old age can accelerate the process of bone resorption.

However, in all these instances, a common finding of highly active ‘osteoclasts’ could be readily visible.

Characteristics of Osteoclasts

These cells contain multiple nuclei with abundant mitochondria and lysosomes, which indicates its ability to perform energy demanding work such as bone resorption. They reside near the outer edge of the bone just underneath the periosteum. This will facilitate osteoclasts the easy access to the mineral dense portion of the bone.

The Steps Involved In Bone Resorption

The process is initiated by the factors mentioned above and with any such stimulus, the number and the activity of osteoclasts will rise. This will be facilitated by various chemical messengers released at the site of immature forms of osteoclasts (preosteoclasts) in the bone matrix. During this first step, many preosteoclasts mature into osteoclasts, which are able to de-mineralize the bone.

Once activated, the osteoclasts can secrete various enzymes including collagenases that are capable of digesting the mineralized bone and its collagen. As a result of osteoclasts invading the periosteum, the densely mineralized bone will break into its constituents while minerals such as calcium gets released to the blood circulation.

Regulating Excess Bone Resorption

When the osteoclasts become highly active and appear abundant in the bony matrix, the most likely result would be an increased destruction of the bone at a rate higher than its formation. Thus, to prevent such overwhelming de-mineralization, the regulatory mechanism in the parathyroid gland is also sensitive to the rising levels of calcium. As such, if it detects the calcium levels to be too high, the secretion of parathyroid hormone will lessen and therefore the resorption process will lose its steam. However, in a disease state, this would not be the main mechanism regulating the bone resorption and therefore the control may not be sufficient to prevent continued bone destruction.


    0 of 8192 characters used
    Post Comment
    • profile image

      James Orr 

      12 months ago

      Fractured humorous on 3/15/19. Surgery two weeks later after swelling went down with an Intramedullary (IM) rod. Sling off at 4 weeks with light physical therapy and more intense physical therapy for next 4 weeks. X ray at 8 weeks showed fracture not starting to heal. Stopped therapy and added Sarmiento Clamshell Brace for 5 weeks, staying in home and not lifting arm. X ray at 13 weeks (last Friday) showed fracture had increased in size.

      Why did this happen? Can it still heal?

    • Scribenet profile image

      Maggie Griess 

      7 years ago from Ontario, Canada

      This is very useful. Also this is an article I will read in depth more than once.

      I always thought we needed to supplement with calcium as we aged for the bone only, but it seems more complex...we need the calcium in our blood so the PTH won't try to reabsorb bone to adjust blood levels of calcium. Fascinating. So glad I have been supplementing with calcium as I am aging! Hopefully I got that right?


    This website uses cookies

    As a user in the EEA, your approval is needed on a few things. To provide a better website experience, uses cookies (and other similar technologies) and may collect, process, and share personal data. Please choose which areas of our service you consent to our doing so.

    For more information on managing or withdrawing consents and how we handle data, visit our Privacy Policy at:

    Show Details
    HubPages Device IDThis is used to identify particular browsers or devices when the access the service, and is used for security reasons.
    LoginThis is necessary to sign in to the HubPages Service.
    Google RecaptchaThis is used to prevent bots and spam. (Privacy Policy)
    AkismetThis is used to detect comment spam. (Privacy Policy)
    HubPages Google AnalyticsThis is used to provide data on traffic to our website, all personally identifyable data is anonymized. (Privacy Policy)
    HubPages Traffic PixelThis is used to collect data on traffic to articles and other pages on our site. Unless you are signed in to a HubPages account, all personally identifiable information is anonymized.
    Amazon Web ServicesThis is a cloud services platform that we used to host our service. (Privacy Policy)
    CloudflareThis is a cloud CDN service that we use to efficiently deliver files required for our service to operate such as javascript, cascading style sheets, images, and videos. (Privacy Policy)
    Google Hosted LibrariesJavascript software libraries such as jQuery are loaded at endpoints on the or domains, for performance and efficiency reasons. (Privacy Policy)
    Google Custom SearchThis is feature allows you to search the site. (Privacy Policy)
    Google MapsSome articles have Google Maps embedded in them. (Privacy Policy)
    Google ChartsThis is used to display charts and graphs on articles and the author center. (Privacy Policy)
    Google AdSense Host APIThis service allows you to sign up for or associate a Google AdSense account with HubPages, so that you can earn money from ads on your articles. No data is shared unless you engage with this feature. (Privacy Policy)
    Google YouTubeSome articles have YouTube videos embedded in them. (Privacy Policy)
    VimeoSome articles have Vimeo videos embedded in them. (Privacy Policy)
    PaypalThis is used for a registered author who enrolls in the HubPages Earnings program and requests to be paid via PayPal. No data is shared with Paypal unless you engage with this feature. (Privacy Policy)
    Facebook LoginYou can use this to streamline signing up for, or signing in to your Hubpages account. No data is shared with Facebook unless you engage with this feature. (Privacy Policy)
    MavenThis supports the Maven widget and search functionality. (Privacy Policy)
    Google AdSenseThis is an ad network. (Privacy Policy)
    Google DoubleClickGoogle provides ad serving technology and runs an ad network. (Privacy Policy)
    Index ExchangeThis is an ad network. (Privacy Policy)
    SovrnThis is an ad network. (Privacy Policy)
    Facebook AdsThis is an ad network. (Privacy Policy)
    Amazon Unified Ad MarketplaceThis is an ad network. (Privacy Policy)
    AppNexusThis is an ad network. (Privacy Policy)
    OpenxThis is an ad network. (Privacy Policy)
    Rubicon ProjectThis is an ad network. (Privacy Policy)
    TripleLiftThis is an ad network. (Privacy Policy)
    Say MediaWe partner with Say Media to deliver ad campaigns on our sites. (Privacy Policy)
    Remarketing PixelsWe may use remarketing pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to advertise the HubPages Service to people that have visited our sites.
    Conversion Tracking PixelsWe may use conversion tracking pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to identify when an advertisement has successfully resulted in the desired action, such as signing up for the HubPages Service or publishing an article on the HubPages Service.
    Author Google AnalyticsThis is used to provide traffic data and reports to the authors of articles on the HubPages Service. (Privacy Policy)
    ComscoreComScore is a media measurement and analytics company providing marketing data and analytics to enterprises, media and advertising agencies, and publishers. Non-consent will result in ComScore only processing obfuscated personal data. (Privacy Policy)
    Amazon Tracking PixelSome articles display amazon products as part of the Amazon Affiliate program, this pixel provides traffic statistics for those products (Privacy Policy)
    ClickscoThis is a data management platform studying reader behavior (Privacy Policy)