What is osteoporosis?

Updated: Jan 19, 2021
  • Author: Ali Nawaz Khan, MBBS, FRCS, FRCP, FRCR; Chief Editor: Felix S Chew, MD, MBA, MEd  more...
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Answer

Answer

Osteoporosis is defined as a progressive systemic skeletal disorder characterized by low bone mineral density (BMD), deterioration of the microarchitecture of bone tissue, and susceptibility to fracture. The reduction in skeletal mass results from an imbalance between bone resorption and bone formation; increased bone resorption or decreased bone formation may result in osteoporosis. The 2 most important factors that contribute to development of osteoporosis are aging and loss of gonadal function. Bone loss in women accelerates quickly during the first years following menopause. [1, 2, 3, 4, 5]

Each year, osteoporosis results in approximately 9 million fractures worldwide. Prevalence increases dramatically with age, particularly in women, rising from 2% at 50 years of age to over 25% at 80 years of age. [2]

Dual-energy x-ray absorptiometry (DEXA) detects small changes in bone mass by comparing the patient's bone density to that of healthy adults (T score) and to age-matched adults (Z score). Assigning the T score permits the early detection of osteoporosis and thus lowers the risk of either hip or spine fractures. However, the use of T scores at different sites and with different techniques has been controversial because intersite and intermodality correlation has been poor (see the images below). [6, 7, 8, 2, 9, 3, 10, 11]

Early detection of vertebral fracture may increase the diagnosis of osteoporosis. It has been reported that detection of severe osteoporosis significantly increased by 17.2% in patients who received vertical fracture assessment (VFA). [3]

Involutional osteoporosis. T and Z scores in an 80 Involutional osteoporosis. T and Z scores in an 80-year-old woman.
Involutional osteoporosis. T and Z scores in an 80 Involutional osteoporosis. T and Z scores in an 80-year-old woman.

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