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.
