Osteoporosis: epidemiology, clinical and para-clinical manifestations

Abstract: Osteoporosis, as the most common bone disease, is a growing public health problem throughout the world, in part because of the increasing numbers of people living beyond the age of 65 years. It is a major risk factor for fracture, which leads to considerable morbidity, mortality, and expense. Franco-Iranian Seminar on Rheumatology (The 4th Collaborative Medical Seminar), Tehran, Iran, May 2005. Osteoporosis, or porous bone, is a “disease characterized by low bone mass and structural deterioration of bone tissue, leading to bone fragility and an increased susceptibility to fractures, especially of the hip, spine and wrist.” The 2000 National Institutes of Health Osteoporosis Consensus Conference has defined osteoporosis as “a skeletal disorder characterized by compromised bone strength predisposing a person to an increased risk of fracture. Bone strength primarily reflects the integration of bone density and bone quality”. Bone density is determined by peak bone mass and amount of bone loss. Bone quality refers to architecture, turnover, damage accumulation (e.g., microfractures), and mineralization. Bone size is also very important and increased periosteal bone apposition enhances bone strength. This strict definition of osteoporosis is largely histologic. In practice, however, one deals mainly with decreased bone density, or osteopenia, without examining bone histology. According to the World Health Organization (WHO) published criteria based on bone density, osteoporosis is defined as a bone mineral density (BMD) greater than or equal to 2.5 standard deviation below the peak BMD of gender- and ethnicity-matched 30-year-old healthy Caucasian women (T-score less than 2.5). Osteopenia (thin bones) is caused largely by osteoporosis, as defined above, although it can also result from mild vitamin D deficiency, hyperthyroidism, or hyperparathyroidism. A history of atraumatic fracture has also been included in the definition of osteoporosis, making it possible to diagnose osteoporosis clinically. Other definitions of osteoporosis restrict the diagnosis to individuals with nonviolent fractures (i.e., fractures that occur with falls from standing height). However, from the standpoint of prevention, this latter definition may be too restrictive.