New Diagnostic Tool Reads Fracture Risk in Drop of Blood

Bone fragility is a major public health problem. The primary cause is osteoporosis, which affects 30% of the Swiss population. Type 2 diabetes, which affects 10% of the population, is a risk factor as it increases the probability of fracture almost twofold. As the population ages, osteoporosis and fragility fractures are expected to increase by 23% in EU countries, from 2.7 million in 2017 to 3.3 million in 2030. In Switzerland, the current annual number of 82,000 fragility fractures is expected to rise to almost 105,000 in 25 years. Bone fragility should be diagnosed before a fracture occurs, because depending on the age of the person and the bone involved, a fracture can lead to severe chronic pain and even increase the risk of mortality. Now, a new device diagnoses bone fragility based on a novel approach via blood sampling. This test is much more specific than current techniques and will significantly improve diagnosis and advance the development of new treatments for osteoporosis.

The basis of this invention by researchers at the University of Geneva (UNIGE, Geneva, Switzerland) lies in the properties of the periosteum, a membrane that covers the bones and plays an essential role in their growth and repair. It secretes a key protein that controls the diameter of the bone and therefore its strength: periostin. During the bone resorption process, the enzyme cathepsin K degrades it. The digested periostin fragment, called k-POSTN, is also found in the blood and thus reflects bone fragility. The interest of this fragment lies in its bone specificity, unlike intact periostin, which has been known to scientists for a long time, but which can also increase in cardiovascular diseases and cancers. After a blood sample has been taken, the amount of k-POSTN is measured in the laboratory using an ELISA test, a widely used method for measuring molecules in a biological sample.

Image: The new technology is based on properties of periosteum, a membrane that covers the bones (Photo courtesy of University of Geneva)

The measurement of k-POSTN improves the prediction of bone fragility by increasing the accuracy and specificity of the techniques currently used to identify people at risk of bone fracture. The new device has the potential to help healthcare professionals identify and monitor those most at risk of developing osteoporotic fractures as well as those with other bone-weakening diseases, including type 2 diabetes. In addition, it allows therapeutic intervention at an early stage, before a fracture occurs, a fact that should undeniably reduce the burden of bone diseases on health systems and significantly improve patients’ quality of life. The new device has been approved for marketing in the European Economic Area and Switzerland and is intended to complement bone densitometry, which is the imaging technique currently used to assess bone fragility.

“This is a process that can unfortunately be biased in the case of type 2 diabetes. The increase in weight and fat mass typical of diabetes blurs the measurement of bone mineral density, which may appear normal even though fragile bone tissue is present. The new device overcomes these limitations,” said Serge Ferrari, head of HUG's Bone Diseases Service, full professor at the Department of Medicine at the UNIGE Faculty of Medicine and co-inventor.

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