The site is no more able to conduct the study

Chronic Obstructive Pulmonary Disease (COPD) is a condition characterized by a progressive and incompletely reversible limitation of airborne gas flow . The association of co-morbidities with COPD and acute flare-ups of respiratory failure contribute to the overall severity of this disease. The prevalence of COPD is high, affecting up to 10% of people over the age of 40 years and causing high morbidity and mortality rates. While COPD is a disease primarily affecting the lungs, it is associated with many extra-pulmonary conditions including sleep apnea, depression, anemia, chronic kidney failure, wasting, cardiovascular disease, skeletal muscle weakness and osteoporosis (OP).

Osteoporosis, characterized by bone quality disorders and low bone mineral density (BMD) leading to a high risk of fractures, is common in COPD patients. For example, studies have reported OP rates ranging from 9% to 69% in COPD patients. The explanatory factors for this low BMD are clearly multiple, involving to varying degrees of importance, vitamin D deficiency, depression, sedentary lifestyle, smoking, corticosteroids, low lean body mass and body mass index, chronic inflammation, low nutritional status, chronic hypoxia and hypercapnia. This is why patients with COPD have a high prevalence of fractures, particularly vertebral fractures (VF) ranging from 30 to 63% depending on the studies. In these patients the existence of thoracic VF is of crucial importance, as each VF is associated with a 9% decrease in the forced vital capacity of COPD patients.

For these reasons the latest HAS recommendations for COPD management indicate that the risk of osteoporosis should be systematically investigated and treated (HAS, 2014).

However, the relationship between densitometric variations and the presence of thoracic VF and the prognosis and severity of the disease is not yet very clear, as studies of these relationships have produced mixed results.

On the other hand, it is well established that patients with a recent diagnosis of COPD have a high prevalence of densitometric OPs and fractures.

Thoracic kyphosis is one of the determinants of the incidence of vertebral fractures. Increased thoracic kyphosis is associated with decreased physical capacity, increased risk of falls and abnormal respiratory function.

In addition, measurement of thoracic kyphosis was previously carried out either indirectly using point coordinates recorded in a database (patients were assessed in the supine position) or more directly using a ruler applied against the back.

Inclusion Criteria:

• Man or woman age > 40
• FEV1/CVF ratio < 0.7 as defined by the Global Initiative for Chronic Obstruction Lung Disease (GOLD).
• Moderate to severe COPD as defined by GOLD (grade C and D)

Exclusion Criteria:

• Presence of metal or plastic parts in the field of examination
• Pregnancy
• Patients who are not affiliated with or do not benefit from a social security system
• Person under guardianship or curatorship