Classification of Osteoporosis

Osteoporosis is defined by low bone quality, strength and increased fracture risk. Primary and secondary osteoporosis are the two forms of osteoporosis classified on the basis of factors affecting the metabolism of bone. Primary osteoporosis develops as a result of aging or menopause-related bone demineralization. Type I/postmenopausal and type II/senile osteoporosis are two subtypes of primary osteoporosis. Secondary osteoporosis is due to pathological conditions and medications other than aging and menopause that lead to deprivation of bone mass and elevated fracture risk. Classification of osteoporosis based on BMD testing with DEXA devised by the World Health Organization utilizes T-score in BMD reporting of women in menopausal transition or postmenopause and men ≥ 50 years. Z-scores are preferred, while BMD reporting in premenopausal women, adults < 50 years of age, and children. BMD alone is not diagnostic of osteoporosis in men < 50 years. The Fracture Risk Assessment Tool Model (FRAX) is a software algorithm that incorporates significant predictors of fracture risk and BMD in individuals to predict the risk of fracture. FRAX predicts the "10-year probability of a major fracture (hip, clinical spine, humerus, or wrist fracture) and the 10-year probability of a hip fracture".