Measurement of BMD

What is fragility fracture

Fracture that is caused by minor trauma

What is abnormal

B shows vertebral fractures since the anterior part of vertebrae is collapsed compared to posterior part

What score is used to diagnose in a DEXA scan

For old person: Use the lowest T score; for young adult use lowest Z score ; look at either L1-L4 or L2-L4

What are the T score ranges

T score <= -2.5 = osteoporosis; T score >= -1.0 = normal

What is the difference between T and Z score

T score is an average for young adult; Z score is compared by age

Indication for BMD

Women aged over 65, men over 70; post menopausal women <65 and men 50-70 years old

Risk factor of osteoporosis

Fragility fracture, on steroid drug, alcoholism/smoking, secondary cause, menopause, CKD, major weight loss, low BMI

Why is low BMI a risk factor for osteoporosis

For bone to be strong there need to be injury → Caused by weight bearing; low BMI = low weight = low weight bearing

What demographic has the highest rate of osteoporotic fracture

T score -1 to -2

Based on FRAX score what is considered high risk

Osteoporotic fracture risk >=20% or hip fracture risk >=3%

What are the pro and con of QCT

Con: more radiation, scanner variability changes HU; pro: useful for scoliosis and obesity, spinal degeneration does not affect result

What defines severe osteoporosis

T score <= -2.5 + risk factor