Overview
Definition
A systemic skeletal disease characterized by low bone mass and microarchitectural deterioration, leading to bone fragility and increased fracture risk.
Epidemiology
Extremely common in postmenopausal women and older men. A major public health issue due to the morbidity of hip fractures.
Etiology & Risk Factors
- Primary: Postmenopausal estrogen deficiency (Type 1) or Age-related (Type 2).
- Secondary: Long-term corticosteroid use, hyperthyroidism, hyperparathyroidism, malabsorption (Celiac).
- Pathophysiology involves osteoclast (bone resorption) activity outpacing osteoblast (bone formation) activity.
Clinical Symptoms
- Often 'silent' until a fracture occurs
- Fragility fractures (occurring from a fall from standing height or less), commonly in the vertebrae, hip (femoral neck), or distal radius (Colles fracture)
- Loss of height and development of kyphosis (Dowager's hump) due to vertebral compression fractures
Clinical Approach
Diagnosis
- DEXA Scan (Dual-Energy X-ray Absorptiometry): Gold standard. A T-score of ≤ -2.5 defines osteoporosis (T-score between -1.0 and -2.5 is osteopenia)
- FRAX Score: Calculates the 10-year probability of a major osteoporotic fracture
Management
- Lifestyle: Weight-bearing exercises, smoking cessation, adequate Calcium (1200mg/day) and Vitamin D (800 IU/day) intake
- First-line Pharmacotherapy: Bisphosphonates (Alendronate, Risedronate) - inhibit osteoclast activity
- Alternative options: Denosumab (RANKL inhibitor), Teriparatide (PTH analog that stimulates bone formation)
Complications
- Hip fractures (associated with high 1-year mortality and severe loss of independence)
- Chronic back pain and deformity from vertebral fractures