What is osteoporosis?

Osteoporosis: Definition, Impact, and Significance

Osteoporosis is a systemic skeletal disease characterized by loss of bone mass and impaired bone microarchitecture that leads to substantially increased risk of fracture. 1

Definition and Pathophysiology

• Osteoporosis is defined as a progressive systemic skeletal disease characterized by low bone mass and microarchitectural deterioration of bone tissue, leading to bone fragility and increased susceptibility to fractures 1
• The World Health Organization (WHO) defines osteoporosis as a bone mineral density (BMD) 2.5 standard deviations or more below the young adult mean value (T-score less than -2.5) 1
• On a cellular level, osteoporosis results from osteoclastic bone resorption not being adequately compensated by osteoblastic bone formation 2
• Age-related alterations to bone microarchitecture differ between men and women:
  • Men experience trabecular bone loss primarily through loss of trabecular thickness while maintaining connectivity 1
  • Women lose trabecular connectivity, which creates a structurally weaker framework 1

Epidemiology and Public Health Impact

• Osteoporosis constitutes a significant public health risk, with an estimated 10.2 million adults in the United States over age 50 having the condition 1
• Approximately one-half of women and nearly one-third of men over age 50 will sustain an osteoporotic fracture in their remaining lifetime 1
• The global burden is increasing, with fracture numbers expected to rise by 310% between 1990 and 2050 1
• The direct cost of managing fragility fractures worldwide exceeds $100 billion USD with indirect costs approaching $200 billion 1

Clinical Manifestations and Consequences

• Common osteoporotic fractures occur in the vertebral bodies, distal radius, proximal femur (hip), and proximal humerus 1
• These fractures are associated with:
  • Decreased quality of life 1
  • Diminished physical function 1
  • Reduced independence 1
  • Significant mortality, particularly following hip fractures 1
• Mortality rates differ between sexes, with men at substantially higher risk of death following fracture than women (10.2% vs 4.7% inpatient mortality after hip fracture) 1
• One-year mortality after hip fracture is 37.5% in men compared with 28.2% in women 1

Diagnosis

• Dual-energy X-ray absorptiometry (DXA) is the primary imaging modality used to screen for osteoporosis 1
• Screening recommendations:
  • Women aged 65 years and older 1
  • Men aged 70 years and older 1
  • Younger individuals with additional risk factors 1
• Diagnostic thresholds:
  • Osteoporosis: T-score ≤ -2.5 1
  • Osteopenia: T-score between -1 and -2.5 1
• Important caveat: Most fragility fractures occur in patients with BMD T-scores higher than -2.5, confirming that fracture risk assessment should not rely solely on BMD 1

Risk Factors

• Age (>70 years) 1
• Low body weight (BMI <20-25 kg/m²) 1
• Weight loss (>10% compared to usual weight) 1
• Physical inactivity 1
• Use of oral corticosteroids 1
• Previous fragility fracture 1
• Additional factors:
  • Alcohol use (increases fracture risk) 1
  • Androgen deprivation therapy 1
  • Cigarette smoking 1
  • Low dietary calcium intake 1
  • Vitamin D deficiency 3
  • Family history of osteoporosis 3

Management Approach

• Prevention strategies:

  • Adequate calcium and vitamin D intake 4, 3
  • Regular weight-bearing exercise 4, 3
  • Smoking cessation 3
  • Limited alcohol consumption 3
  • Fall prevention measures 3

• Pharmacological treatment options:

  • Antiresorptive agents (bisphosphonates, denosumab) 4, 3
  • Anabolic agents (teriparatide) 3
  • Selective estrogen receptor modulators (raloxifene) 3
  • Hormone replacement therapy in appropriate candidates 4

• Coordination of care:

  • Primary care physicians should take the lead role in osteoporosis management after initial diagnosis 5
  • Specialists (endocrinologists, rheumatologists) should manage complex or treatment-resistant cases 5
  • Regular bone mineral density testing should be scheduled with clear follow-up plans 5

Important Clinical Considerations

• The "osteoporosis care gap" reflects that approximately 70% of individuals at high fracture risk have not undergone assessment and treatment 1
• Most low-trauma vertebral fractures do not present with pain, making dedicated vertebral imaging important in high-risk patients 1
• Fracture risk increases progressively with decreasing BMD, with risk increasing 2-3 fold for each standard deviation decrease 1
• Treatment adherence is a significant challenge, with 30-50% of patients not taking osteoporosis medications correctly 3