• Established by the WHO in 1994 as a radiographic tool to determine fracture risk
• Measures T-score, which compares patient’s bone mineral density to that of a young-adult reference population (“normal”), and is reported as standard deviation (SD)
  • Normal is a bone density = 0.0 +/- 1
  • Osteopenia/low bone mass is = -1 to -2.4
  • Osteoporosis is lower than -2.5
• Low BMD predictors fractures and each 1 SD decrease increases risk of fracture by about 2x

Dual-energy x-ray absorptiometry (DXA) is gold standard for assessing BMD

• Measures at the hip, lumbar spine, +/- radius
• There are other methods as well as newer technologies in development
• Click for more DXA pearls

Pearl: A major drawback is that most fragility fractures occur in individuals without BMD-defined osteoporosis (such as osteopenia range) and thus is a relatively poor tool by itself.

• FRAX Calculation Tool
  
• Established in 2008 as a probability based, risk factor approach to fracture risk over 10 years to capture those who were likely to fracture but were missed by only using bone mineral density. (See history of FRAX)

• Goal was to determine which patients who did not have osteoporosis on BMD would develop fractures and thus benefit from intervention

• Important risk cut offs – 10-year probability of fracture:
  • ≥3% at hip OR ≥ 20% of any major osteoporotic fracture

• Risk factors:
  1. Age
  2. Sex
  3. Weight
  4. Height
  5. Previous fracture in adult life (that an otherwise healthy individual would not have)
  6. Parent with a hip fracture
  7. Current smoker
  8. Glucocorticoids: >3 months at oral dose of 5+ mg prednisone
  9. Rheumatoid arthritis
  10. 3+ alcohol units per day
  11. Femoral neck BMD

Click for more FRAX pearls