Steps for strong bones: 1. what is Osteoporosis?
Osteoporosis = WEAK BONES
Osteoporosis is a disease characterized by low bone mass (bone density) and deterioration of the microstructure of bone (decreased bone quality). These changes lead to bone "fragility" and an increased risk breaking bones. Both women and men are affected by osteoporosis, a disease that can be prevented and treated.
Bone Strength = Bone Density + Bone Quality
Bone density is a measurement of how much bone you have, and is assessed with a bone density scan (which will be discussed in step 2). Bone quality is comprised of the underlying structure of bone, and this is not assessed with a bone density scan. It is estimated that bone strength is approximately 60% dependent on bone density, and 40% dependent on bone quality. Multiple factors change bone quality, including tobacco and alcohol use, genetics, but largely age. Theoretically, if you could keep the same bone density for your entire life, after the age of 50, your fracture risk approximately doubles every 10 years.
The above photos demonstrate micro architecture. The left photo is of the Eiffel tower. Take note of the interconnections that make up the structure. The support beams, trusses, and studs provide the structural integrity. The photo on the right depicts the micro architecture of bone in our bodies which provides structural integrity similar to buildings. With osteoporosis, the bone and interconnections become thinner and inadequate, which contributes to bone weakness.
Both of these photos are of bone, however the left is normal bone, and the right is osteoporotic bone.
Consequences of Osteoporosis
Osteoporosis is known as a silent disease, because it does not cause any symptoms until someone has a broken bone (fracture). Think of osteoporosis like other silent diseases, such as high cholesterol or high blood pressure. For the most part, those diseases do not cause ongoing symptoms but do have consequences such as increasing the risk of strokes and heart attack.
It is estimated that 50% of women and 25% of men will have an osteoporotic fracture at some point in their lifetime. Often, the first fractures people sustain are wrist fractures or ankle fractures. As people age and their osteoporosis progresses, people will sustain fractures of larger bones such as hip and spine fractures.
We talk a lot about preventing hip fractures. The reason is that statistics associated with hip fractures are grim. For example, about 20% of women and 25-30% of men will die within one year of a hip fracture. 30% will also ultimately live in a nursing home full time. These unfortunate statistics are not usually directly due to the fracture itself, but problems associated with the stress on other organs and loss of independence/ability to mobilize. It is estimated that at least 50% of hip fractures could have been prevented with appropriate screening and treatment.
In September 2019, the National Osteoporosis Foundation released a report that outlines the clinical and human impact of osteoporotic fractures on the Medicare population. The following key findings from the report show the need for increased focus on post-fracture care:
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Approximately 2.3 million osteoporotic fractures were suffered by 2 million Americans covered by Medicare in 2015.
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Only 9 percent of women covered by Medicare who suffered an osteoporotic fracture were screened for osteoporosis with a bone mineral density test within six months following their fracture. Other evidence shows that fewer than 20% receive effective treatments post-fracture.
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Over 40 percent of Medicare beneficiaries with a new osteoporotic fracture were hospitalized within a week after their fracture and nearly 20 percent died within 12 months following a new osteoporotic fracture.
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The report concludes that reducing between 5 percent and 20 percent of these “secondary” fractures in 2015 could have reduced Medicare FFS spending by $310 million to $1.2 billion over a follow-up period that lasted up to 2 to 3 years after a new osteoporotic fracture
Risk Factors for Osteoporosis
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Gender (female higher risk)
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Ethnicity
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Body size
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Family History of osteoporosis
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Certain medical conditions (including but not limited to diabetes and rheumatoid arthitis)
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Certain medications (including glucocorticoids, some anti-seizure medications, and several others)
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Tobacco use
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High alcohol intake
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High caffeine intake
Why Does Osteoporosis Happen?
Understanding some basic bone science and why osteoporosis happens can help you understand how the recommendations for lifestyle modifications and medications can help.
All of our life, our bone is constantly being replaced. This is similar in other organ systems, including our skin and internal organs. The purpose of our bodies replacing bone tissue is to keep it healthy—to reshape bone or to replace bone from micro-injuries that can happen due to daily activity. Bone remodeling is also the process that enables broken bones to heal. This life-long process is carried out by two main factors: Bone resorption and new bone formation. Osteoclasts are cells that remove old bone and are responsible for bone resorption. Osteoblasts are bone building cells and are responsible for bone building. It is estimated that the average person has a newly replaced skeleton about every 8 years due to bone remodeling.
Bone Resorption: Cells called osteoclast remove old bone
Bone Formation: Cells called osteoblasts build new bone
First of all, osteoclasts and osteoblast function at varying different rates throughout our lives. When we are children, adolescents, and young adults, our osteoblasts are functioning at a greater rate and this results in increasing bone density. This process is actually called bone modeling. Somewhere around the age of 25 or 30 we reach peak bone mass, which is the time where we have the most bone that we are going to have in our lifetime. After this, osteoclast activity and osteoblast activity even out, and after about the age of 30, bone resorption activity slowly starts overtaking bone formation. From then on, women and men both lose bone mass although appropriate lifestyle optimization can slow down or prevent bone loss. The amount of bone that people have later in is somewhat dependent on the amount of bone they had at peak bone mass.
Menopause also causes significant bone loss in women. Estrogen is very protective for bone (it inhibits osteoclasts and promotes development of osteoblasts). When women go through menopause, estrogen levels drop and women start losing bone at a greater rate. Some studies show that women loose about 20% of their bone within the first 7 years of menopause.
In addition, bone quality decreases with age and also contributes to increase fracture risk.
Interventions recommended for osteoporosis work by restoring the balance between osteoclasts and osteoblasts. For example, weight bearing exercise is recommended because it can increase osteoblast formation to which can improve bone mass by increasing bone formation. Medications for osteoporosis also work by restoring this balance: by either stimulating osteoblast activity to build new bone (medications called anabolics) or by slowing down bone loss (called anti-resorptives). More to come on this in future sections.
Below is a video that explains bone remodeling, and how various different factors can affect this process. This is an educational video that was made/produced by Amgen.
