Bone Growth, Bone Health & Osteoporosis

Parallel between normal, trabecular structure in the non-osteoporotic bone (above) and the reduced trabeculae of the osteoporotic bone (below).
Parallel between normal, trabecular structure in the non-osteoporotic bone (above) and the reduced trabeculae of the osteoporotic bone (below).

What is Osteoporosis?

Simply stated, osteoporosis is bone loss. How it occurs, and how it affects other body systems, however, is complex. In this hub, I will discuss a few basic causes of osteoporosis; some of its earliest warning signs; a few general treatments; and how osteoporosis' effects can be lessened and/or prevented?

What Bone is and What Bone is Not:

Contrary to popular thought, bone tissue is living and in a constant state of change. For people under the age of 30, bone remodeling (the term referring to the replacement of old bone with new bone) is continuous. Bone remodeling is such an active process in fact, that approximately every 10 years (between the ages of 2-30) your entire skeletal system is remodeled; that is, new bone replaces old bone. After the age of 30, however, bone remodeling slowly decreases thus leading to eventual loss of bone density and strength. Osteoporosis (or porous bone) is the end result of years of reduced bone remodeling and subsequent bone loss. The causes of osteoporosis are varied, but improper nutrition, lack of exercise, and genetics are often stated as the top three.

The internet is full of information on osteoporosis. My purpose here will be to explain in simple terms a few of the reasons osteoporosis develops as well as discuss certain preventative measures designed to disrupt its progression. To begin with, a few definitions are needed for clarification.

Important Medical Terminology Relating to Bone:

 

Osteoblast: Type of bone cell that produces collagen (a major component of bone and skin), and proteoglycans, proteins designed to hold water molecules and subsequently form part of the bone cell matrix.

Osteocyte: A mature bone cell; an osteoblast completely surrounded by calcified bone matrix.

Osteoclast: Large bone cells with several nuclei designed to break down bone cells (resorption) in order to release their chemical compounds, primarily calcium and phosphates.

Trabeculae: Interconnecting rods of bone plate arrranged within the interior of bone; often resembling a series of arches and trusses. Trabeculae provide great inner strength for bones.

Woven Bone: Young bone often found in newborns and infants consisting of non-calcified bone cells, primarily collagen, randomly-oriented.

Cancellous Bone: Often referred to as "spongy bone" due to the presence of interwoven trabeculae. Blood vessels and marrow often fill the trabecular spaces providing nutrients, RBC production, and fat storage.

Compact Bone: Dense, older bone with few spaces within its matrix. Hard bone.

PTH: Parathyroid Hormone is a hormone released from the parathyroid gland that is the major regulator of blood Calcium (Ca) levels.

Calcitonin: Hormone produced by the thyroid gland that decreases blood Calcium levels.

A great illustration showing the infrastructure of trabeculae within a bone. These are the structures that eventually deteriorate with osteoporosis.
A great illustration showing the infrastructure of trabeculae within a bone. These are the structures that eventually deteriorate with osteoporosis.

How Bones Grow:

Among other causes (such as the hormones estrogen and testosterone) bone grows as a response to physical stress.

From birth to adulthood, your bones grow; both in length and width as well as in strength and hardness. In addition, bones in different parts of your body grow at different rates primarily due to the amount of weight-bearing stresses placed upon them. This is one of the reasons young people grow: activity. Young people are historically more active walking, running, cycling, lifting heavy objects, etc. The resulting stresses on young bones therefore stimulate their growth. Of course, there are other variables in play (such as hormones and genetics), but in general, physical activity stimulates bone growth.

After birth, bone grows by a process known as appositional growth; which involves osteoblasts layering additional bone cells on the outside of existing bone. Over time, compact bone develops near the perimeter of bones and cancellous bone develops interiorly. It is this interior structure of canellous bone (with its trabecular framework*) that leads to the effects of osteoporosis.

* Note the term, trabeculae, above

Information on Trabecular Bone:

Trabecular bone is found in the shafts and ends of the long bones, within spinal vertebrae, and inside the flat bones of the pelvis. As the scaffolding network of trabeculae is built (along interior stress lines), bone strength is created without adding excessive weight to the body. This scaffolding also allows for blood vessels and other connective tissue to infiltrate the bone thus providing essential nutrients. As bone remodeling continues to maturity (around age 30), bones grow in strength; becoming very responsive to stress. As we age, however, in order to maintain as much of this structural integrity as possible, there are certain activities and lifestyle changes that should be made. We need, in essence, to take care of our bones!

A microscopic image of trabecular bone and its surrounding matrix.
A microscopic image of trabecular bone and its surrounding matrix.
Another microscopic image of cancellous bone and its surrounding matrix.
Another microscopic image of cancellous bone and its surrounding matrix.

Causes of Osteoporosis:

Outside of genetics (which cannot be altered unfortunately) the primary causes of osteoporosis are lack of physical, weight-bearing exercise and calcium/mineral depletion. Let's address each individually.

Lack of Physical, Weight-Bearing Exercise:

As previously mentioned, bone grows while we're young partially in response to physical stress. When stress is placed on a bone, specific lines of stress are created within the bone stimulating trabeculae to form around them. This is why bone is so strong. Wherever the most stress is, so is the increased structure. On the flip side, as we age our physical activity slows, and the stresses placed on our bones decrease. Don't worry too much, though. This happens to all of us. How we choose to respond, however, is the key to overcoming osteoporosis' worst symptoms.

A short list of these symptoms and effects include:

  • A general weakening of bone structure
  • An increased susceptibility of fracture, primarily in the larger, synovial joints, e.g., the hips, shoulders, and arms
  • Spinal fractures and the development of excessive vertebral curvature
  • Reduced physical mobility

By increasing your physical activity (even in small amounts) you increase your chance of lessening some of osteoporosis' effects.

In short, one cause of osteoporosis is the lack of physical, weight-bearing exercise. Next, let's discuss another leading cause of osteoporosis: poor nutrition.

Calcium and Other Nutrient Depletion:

Eating right makes good sense for many reasons, but when it comes to osteoporosis, eating nutritiously might be very well the difference between poor and healthy bones.

A primary component of adult bone is a mineral compound known as hydroxyapatite, an inorganic crystal comprised mainly of calcium, phosphate, and hydroxyl ions. This molecule (as illustrated by its chemical components) is built around calcium. Thus the reason why our bones require so much of the element. The lack of calcium (along with its companion hormone, vitamin D) quite literally fans the flames of osteoporosis. And that is NOT a good thing! Even though calcium absorption and subsequent bone growth is slowed after age 30, the necessary ingredients to maintain healthy bone are still required, i.e., calcium, phosphorus, and a few other minerals. 

The bottom line is this: make sure you get enough calcium and vitamin D in your diet. You can do so by eating plenty of vitamin D-fortified dairy products and green, leafy vegetables.

As an aside, other dietary requirements needed in lesser quantities for healthy bone include: vitamin A, vitamin K, magnesium, zinc, and copper.

So do your part. Eat right and exercise.

Ways to Decrease Your Risk of Osteoporosis:

If you're searching for ways to decrease your risk of osteoporosis, here are a few precautions proven to be quite effective.

  • Make sure you have adequate calcium and vitamin D intake.
  • Incorporate a regular routine of weight-bearing exercise.
  • Limit your alcohol intake and quit smoking. Both been linked to reducing your risk of developing osteoporosis.

If you are at risk, however, there are additional medical interventions that also work quite well. These interventions, of course, should always be accompanied by professional medical guidance and prescription. Three of these medical interventions are: estrogen and estrogen receptor modulators (for post-menopausal women) and calcitonin, which is a known osteoclast inhibitor.

 

Exercises to Improve or Help Prevent Osteoporosis:

Weight-Bearing Exercises: High-Impact

These exercises involve moving your body against gravity in an upright position. High-impact exercise is designed primarily for younger individuals still building bone, and who do not have osteoporosis.

A short list would include the following exercises:

  • Aerobics
  • Stair Climbing
  • Rope Jumping
  • Running, or speed walking
  • Racket sports

Weight-Bearing Execises: Low-Impact

Exercises similar to high-impact, but designed for individuals unable to perform high-impact exercise. This group of exercises is helpful in building and maintaining bones with less stress placed on the body.

A short list would include the following exercises:

  • Low-impact aerobics
  • Walking
  • Low-impact step machines
  • Elliptical machines

Strengthening and Resistance Exercises:

Strength and resistance exercise is designed to activate parts of the body against gravity with added weight or resistance. The general purpose is to create stress on the bones in order to stimulate bone growth, or maintain bone integrity.

A short list would include the following exercises:

  • Weightlifting (both light and heavy)
  • Resistance band training
  • Measured resistance weight machines
  • Pull-ups and push-ups (or other exercises using your own weight as resistance)

Low, To Non-Impact Activities:

This grouping of exercises helps improve overall balance, posture, and general muscle tone. Balance and posture exercises, in theory, increase our centers of propioception (balance centers) and decrease the occurrences of falls and subsequent injury.

A short list would include the following exercises:

  • Tai Chi
  • Yoga
  • Pilates

Non Weight-Bearing, Low-Impact Exercises:

These are activities that don't necessarily build bone, but assist in overall cardio-vascular health, and should therefore make a good addition to any osteoporosis or training regimen.

A short list would include the following exercises:

  • cycling
  • Swimming
  • Water aerobics




Bone Health Conclusion:

Our bones and overall skeletal system provide an incredibly strong system for maintaining structural body stability; allow for the attachment of muscles, ligaments, and tendons; create storage for a variety of minerals and fat; and are the primary site of red blood cell production.

As you can see, our bones are extremely important. So taking good care of them should be of the highest priority.

Here's to your soild bone health!

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Comments 20 comments

breakfastpop profile image

breakfastpop 6 years ago

Great article packed full of valuable information.


Rob Jundt profile image

Rob Jundt 6 years ago from Midwest USA Author

Thanks Breakfast pop! This subject is so rich, I'm sure this hub will be added to at some time. I'm glad you found it helpful. Thanks again! Rob


De Greek profile image

De Greek 6 years ago from UK

What a wonderful complete analysis. Thank you :-)


Rob Jundt profile image

Rob Jundt 6 years ago from Midwest USA Author

Thanks De Greek! I feel the more information people have, the better their lifestyle decisions can be. Thanks for dropping by and leaving such an encouraging comment!


Deltachord profile image

Deltachord 6 years ago from United States

This article is jam packed with important information. Good job.


Rob Jundt profile image

Rob Jundt 6 years ago from Midwest USA Author

Thanks Deltachord. My hope is to inform and your comment is very well-received. Have a great day! Thanks for reading!!


Deltachord profile image

Deltachord 6 years ago from United States

You're welcome Rob...keep writing.


rls8994 profile image

rls8994 6 years ago from Mississippi

Good information to have. I try to walk a few times a week so maybe that's doing my bones good. Really great hub!


Rob Jundt profile image

Rob Jundt 6 years ago from Midwest USA Author

Walking, or any other type of weight-bearing exercise, is NEVER bad for the bones... or the heart! Thanks for reading!


Jenette Paulson 5 years ago

I found this information to be extremely valuable. My sister broke her tibia 9 weeks ago but it is not healing. Her physician has recommended surgery to mned her leg since bone regeneration was not occuring. This article helped me understand what life style changes she needs to make to get better.

Jenette


eventsyoudesign profile image

eventsyoudesign 5 years ago from Nashville, Tennessee

The medical establishments answer to Osteoporosis is drugs! Drugs that don't work and can even lead to fractures. Your information is very detailed and easy to follow. I work a job where I walk constantly and lug heavy loads of equipment. I truly believe this helps my bones. Great article, more to say, but I will shut-up. Thanks for sharing this much needed info with the world. Teresa


Rob Jundt profile image

Rob Jundt 5 years ago from Midwest USA Author

Events you design. First of all, thanks for the visit and kind comments. And yes, taking care of your bones is a BIG deal. Now that I'm in my second year of PT school, I can physically see the effects of too much abuse to our bones. If we allow the damage to occur sight unseen, which happens in most cases, the results can literally be crippling. As you mentioned, drugs are far too over-prescribed with the effects sometimes worse than the disability. The chemistry of the body is WAY TOO complex for one drug to target one tissue type and none others. It just does not work that way. The truth is that our body was perfectly designed for work and movement. Unfortunately, our culture does not lend itself to this lifestyle most of the time. Obesity, improper nutrition, and a lack of overall physical activity are fast becoming epidemic. This is what I see in class and the clinic. Eat right and get moving and your body will respond.

Thanks again,

RJ


DePuy Pinnacle Recall 5 years ago

I have been told that the body requires an adequate amount of Vitamin D to aid in the absorption of Calcium. I have been trying to reduce the progression of my osteoporosis after having some health issues on my hips.

I have had a DePuy Pinnacle hip implant in the past, and have heard reports about the possibilities of a recall. This is extremely making me anxious. There are some evaluations regarding the Pinnacle case on this internet site: http://www.depuypinnaclerecall.com

What are your thoughts on this recall?


Rob Jundt profile image

Rob Jundt 5 years ago from Midwest USA Author

...Recall:

You know more about it than I, thus I can't make an educated opinion. I would say, though, to make sure you do plenty of research on the procedure to reverse the THA. As you know, the rehab is quite painful and long. Best wishes!

RJ


Dr Tunio DVM 5 years ago

Excellent article and good information about anatomy of bone .Thanks.


Rob Jundt profile image

Rob Jundt 5 years ago from Midwest USA Author

Dr. Tunio:

Thanks for stopping by and reading. It is always good to hear such kind comments. I feel that as our population ages, knowledge about potentially hidden diseases such as osteoporosis becomes all the more important. Have a great day.

RJ


Osteoporosisbook profile image

Osteoporosisbook 4 years ago from Vancouver BC

Great information about osteoporosis.Unfortunately not many people are aware of their risk of developing this disease


Rob Jundt profile image

Rob Jundt 4 years ago from Midwest USA Author

Osteoporosisbook: Yes, I agree. Glad the information was helpful. Have a great day.


Darlene 4 years ago

North of Boston (ie all of Canada) even a GREAT diet will not provide sufficient vitamin D to support calcium absorption. I was taking 2,000IU vitamin D and my blood levels showed deficiency by January. www.osteoporosis-vitamins.com


Rob Jundt profile image

Rob Jundt 4 years ago from Midwest USA Author

Darlene:

I am not a Dr. but that seems like a lot of Vitamin D intake without any results. I would be curious to know why. Just a thought. Thanks for reading!

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