Trabecular Bone Score and the Quest to Predict Who Will Fracture

Every year, 178 million new osteoporotic fractures occur worldwide. These fractures are painful, costly, and sometimes life-limiting. In hopes of preventing these fractures, medical systems around the world have sought ways to identify those at highest risk of fracture. In Traditional Chinese Medicine, the energy meridian system of the kidney is evaluated, as it is considered to largely determine bone health. According to the 5,000-year-old Indian health science Ayurveda, those with an imbalance of the elements air and ether (known as Vata dosha) are at increased risk of fractures.

Westernized countries have taken the route of X-ray technology to predict who will fracture and define osteoporosis. You may have heard of the Trabecular bone score (TBS))the “new kid on the block” in X-ray fracture risk assessment. Let’s begin by placing TBS in its proper historical context.

Timeline of US fracture prediction search: Where TBS fits in

• 1985, Harvard University, first hand account, since I was there

In 1985, a small group of bone researchers met at Harvard University to announce their groundbreaking development of advanced X-ray technology that could measure bone density. I attended this meeting and felt an air of excitement and optimism when we were told that science would now be able to predict who would fracture using this bone density measuring machine. This was the birth of the DEXA bone density device that is still used today.

These new bone density testing machines were put into service and hundreds of thousands of selected women and men underwent bone density testing. The data from these 10 years were analyzed over time.

• 1994, Geneva, Switzerland

A handful of doctors met in Geneva, Switzerland, in 1994, under the auspices of the World Health Organization. Using 10 years of bone density testing data, they developed a new definition of osteoporosis and a new way to predict fractures. By its action, osteoporosis would now be defined by bone density T scores. As a result of these decisions, you are now said to have “osteoporosis” if your T score is -2.5 or higher.

As data on the correlation between bone density T score and fracture risk over the next 20 years were analyzed, the inability of bone density testing to predict fractures became apparent.

Researchers introduced FRAX (Fracture Risk Assessment Tool) as an adjunct to bone density testing to improve fracture prediction. The FRAX questionnaire consists of 11 known clinical risk factors for osteoporosis (age, sex, weight, height, previous fracture, parental hip fracture, current smoking, glucocorticoid steroid medications, rheumatoid arthritis, known secondary osteoporosis, and alcohol intake). .

The hope was that the addition of this FRAX questionnaire would improve the predictability of fractures from DEXA bone density results. Success was limited as there are more than 100 risk factors for osteoporosis.

A comprehensive analysis of the correlation between bone density scores and fracture incidence revealed that fracture probability could not be effectively predicted by DEXA bone density. It was shown that up to 80% of all osteoporotic fractures occurred in those who did not have an osteoporotic T score of -2.5 or higher. Additionally, many of those with an osteoporotic T score did not fracture.

• 2015, Trabecular bone scoring

In 2015, the International Society of Clinical Densitometry published its first official position on Trabecular bone score (TBS). TBS was then used as an adjunct to DEXA bone density testing. Again, the hope was to improve the fracture prediction ability of the DEXA bone density test.

Trabecular Bone Score (TBS): What is it?

At the Center for Better Bones, we consider trabecular bone scoring to be an interesting attempt to rectify some of the shortcomings of DEXA bone mineral density. Specifically, the DEXA bone density test does not reveal actual bone strength, and bone strength is what likely predicts fracture.

The TBS is a parameter that attempts to capture bone strength by evaluating the microarchitecture of the lumbar (lower spine) trabecular bone (internal cancellous bone). This is done by magnifying and analyzing the radiographic image from the bone density testing machine. The goal is to discern differences in three-dimensional microarchitecture between two-dimensional DEXA measurements that exhibit similar bone mineral density.

To date, several researchers have suggested that a higher TBS value is associated with better and more fracture-resistant bone microarchitecture. A lower TBS value, they report, is associated with weaker bone microarchitecture and more prone to fractures.

However, determining who will fracture is a complicated task, and not all research on TBS supports its value for fracture prediction. For example, one study suggested a significant predictive value of TBS fractures for Caucasian American women, but not for African American or Mexican American women. Overall, many more years of study will be needed to reveal the true fracture predictive value of TBS.

However, at the Center for Better Bones we believe that for some, TBS could be a valuable complement to the current DEXA bone density test. However, this test is not widely available. Currently, few DEXA bone testing devices have the necessary software to produce the trabecular bone score and it may be difficult to find one in your area.

To find a bone testing device that can also give you a TBS score, you can ask the office where you perform your DEXA test. We have been lucky to find a quality technician in Body analysis in St. Louis, Missouri. Watch this short video with Dr. Brown and our colleague Johnny Harper from Body Analytics to learn more about why this test could benefit you and why you should seek out an experienced technician.

References

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Järvinen, TLN et al. 2015. Overdiagnosis of bone fragility in the search to prevent hip fracture. BMJ 350:h2088.

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