Osteoarthritis: an innovation to improve its management

Affecting nearly 600 million people worldwide, according to the WHO, osteoarthritis remains one of the most common pathologies of aging, with a slightly higher frequency in women. In France, nearly 7 million people are affected. This disease attacks the cartilage of the joints, most often the knee or hip, causing chronic pain and significant difficulty walking. In fact, it has become one of the major causes of sedentary lifestyle among the elderly and in turn promotes all the serious complications that this lifestyle entails: increased cardiovascular risk, hypertension, diabetes, etc.

In the absence of a cure for osteoarthritis, treatment aims to relieve pain and maintain mobility to slow the progression of the disease and minimize the impact on quality of life. But for this, it is essential to intervene as early as possible in the evolution. However, to date, the diagnosis remains very late. An American study, published in Science Avances, offers hope of identifying people at risk very early. From blood samples, researchers identified a series of biomarkers making it possible to predict knee osteoarthritis up to eight years before the first symptoms appear.

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The team compared blood serum samples taken at different times in life from 200 British women, half of whom were diagnosed with knee osteoarthritis. These analyzes took into account the body mass index (BMI) and the age of the patients, two known risk factors for osteoarthritis. By screening the samples, the scientists found that 6 blood proteins were found at significantly higher levels in the serum of affected women. Their dosage made it possible to predict the disease in 77% of cases, up to 8 years before the appearance of the first symptoms.

Overall, the majority of these proteins were involved in triggering knee inflammation, more specifically at the level of the synovial membrane which lines the inside of the joint. Normally, the synovium has the function of lubricating the joint and therefore essentially has a mechanical role. “Chronic inflammation of this membrane could contribute to accelerate the degeneration of cartilage, increasing pain and reducing mobility of the joint, conditions conducive to the development of osteoarthritis. But this is only a hypothesis because until now, there was no consensus on the inflammatory origin of this disease. This is why this study is interesting,” underlines Francis Berenbaum, head of the rheumatology department at Saint-Antoine hospital in Paris.

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This discovery opens up new perspectives in the management of the disease. “This means that we could, using a simple blood test, predict subjects at risk and therefore implement preventive strategies in order to reduce the appearance and progression of the disease,” explains Yves Henrotin, president of the Osteoarthritis Foundation and professor at the University of Liège. To date, there is no cure for osteoarthritis. Its treatment consists of alleviating painful symptoms by taking painkillers or anti-inflammatories. In the event of intolerance to these medicinal treatments, doctors may resort to cortisone injections, hyaluronic acids or even the installation of prostheses. However, these options have mixed effectiveness and 20% of patients continue to have pain on a daily basis.

This is why finding ways to screen subjects at risk represents a major challenge in the prevention of this pathology. This would make it possible to act upstream on the avoidable risk factors for osteoarthritis: excess weight, in particular, contributes to accelerating the deterioration of cartilage by exerting pressure on the joints. “If we can predict that an obese person is at high risk of developing osteoarthritis of the knee, this provides a double argument for urgently treating this excess weight,” explains Dr. Berenbaum . Likewise, knowing that one in two people who have suffered knee trauma present with osteoarthritis within 10 years, the detection of subjects at high risk would make it possible to implement targeted therapeutic actions, for example through the use of physiotherapy.

This study nevertheless has some limitations. “77% is a good discriminatory performance, but this still leaves a large margin of diagnostic error for approximately 1 in 4 patients,” underlines Professor Henrotin. Another problem: the markers identified by scientists are probably not specific for osteoarthritis. “In addition to articular cartilage, these compounds are found in other tissues that have no role in osteoarthritis, notably connective tissue, which increases the risk of diagnostic errors,” warns the professor. Further research is therefore necessary to refine these prediction parameters which must also be studied on larger cohorts, including women and men, before considering their possible routine use.