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INTRODUCTION

ESSENTIALS OF DIAGNOSIS

  • Osteoporosis is a systemic skeletal disease characterized by low bone mass and microarchitectural deterioration of the bone tissue, with a consequent increase in bone fragility and susceptibility to fracture.

  • Osteoporosis is a “silent” disease, but its complications, especially hip and vertebral fractures, may result in decreased functional independence, pain, kyphosis, and diminished quality of life.

  • The prevalence of osteoporosis and fragility fractures increases with age.

  • Osteoporosis is more common in women than in men, but at least a fourth of fragility fractures occur in men.

GENERAL PRINCIPLES

Osteoporosis is a skeletal disorder characterized by compromised bone strength, resulting in bone fragility and susceptibility to fractures. Bone strength is a function of bone mineral density (BMD) and bone quality. Bone quality refers to the architecture, bone turnover, damage accumulation, and mineralization occurring at the bony matrix. Bone mass is assessed using bone density measurements, particularly dual x-ray absorptiometry (DXA), but there is no agreed-upon way to measure bone quality in a quantitative and comparable way.

Given these limitations, the World Health Organization (WHO) has defined osteoporosis as the condition of having a BMD that is >2.5 standard deviations lower than the BMD of a sex-matched young adult. Osteoporosis may also be defined by the occurrence of its main complication, fragility fractures. Fragility fractures are bone fractures that result from poor bone strength in the setting of minor trauma or no trauma. These fractures most often result from a fall from standing height or less and involve the thoracic and lumbar vertebrae, hip, proximal humerus, wrist, ribs, and pelvis. The skull, cervical spine, hands, feet, and ankles are less commonly affected by osteoporosis, and fractures of these bones are generally not labeled as fragility fractures.

Osteoporosis is a disease with its origin in childhood. Although genetic factors primarily account for peak bone mass, environmental factors such as nutrition and exercise can alter the genetically determined pattern of skeletal growth. Illness and medications during a person’s lifetime can impact the accrual of peak mass such that individuals start at a lower peak bone mass. Modulation of peak bone mass can even occur during intrauterine life and is affected by maternal nutrition, smoking, and level of exercise. During adulthood, bone tends to have a steady state of formation and resorption with a stable bone mass. For women, menopause marks the start of increased bone resorption. For most older adults, bone resorption exceeds bone formation, and certain illnesses and medications can accelerate this process.

Older adults are particularly susceptible to complications of osteoporosis. Comorbidities, such as cognitive and gait impairments, predispose the individual to falls and the development of fragility fractures.

EPIDEMIOLOGY

The United States has approximately 52 million individuals with low bone mass: 10 million with osteoporosis and 43 million with osteopenia, which is a designation the ...

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