OSTEOPOROSIS
Low Bone Mass | Fragility Fractures | DEXA Diagnosis
WHO DEXA Categories
Critical Must-Knows
- DEXA T-score: At or below -2.5 = osteoporosis. -1.0 to -2.5 = osteopenia. Use femoral neck.
- Fragility Fracture: Low-energy fracture = clinical osteoporosis, treat regardless of DEXA
- Bisphosphonates: First-line (alendronate weekly, zoledronic acid yearly) - 40-50% fracture reduction
- Denosumab: Anti-RANKL antibody. CAUTION: Rebound vertebral fractures if stopped
- Anabolics: Teriparatide (PTH analog), romosozumab (anti-sclerostin) for severe disease
Examiner's Pearls
- "T-score at or below -2.5 = osteoporosis
- "Fragility fracture = treat regardless of DEXA
- "Bisphosphonates are first-line
- "Hip fracture = 20% 1-year mortality
Clinical Imaging
Imaging Gallery
Critical Osteoporosis Exam Points
Fragility Fracture = Treat
Any fragility fracture = clinical osteoporosis. Treat regardless of DEXA. Prior fracture is the STRONGEST predictor of future fracture.
Denosumab Rebound
Do NOT stop denosumab abruptly. Must transition to bisphosphonate. Stopping causes rapid bone loss and rebound vertebral fractures.
FRAX Calculator
Use for treatment decisions. 10-year fracture risk. Treat if hip fracture risk greater than 3% or major osteoporotic fracture greater than 20%.
Fracture Liaison Service
FLS reduces re-fracture rate. All fracture patients should be screened and treated. Evidence-based model of care.
Quick Decision Guide
| Scenario | T-score | Treatment | Key Action |
|---|---|---|---|
| Normal screening | At or above -1.0 | Lifestyle: Ca, Vit D, exercise | Re-screen in 5-10 years |
| Osteopenia | -1.0 to -2.5 | Calculate FRAX | Treat if FRAX high or risk factors |
| Osteoporosis | At or below -2.5 | Bisphosphonate | First-line pharmacotherapy |
| Fragility fracture | Any T-score | Treat immediately | FLS referral, bisphosphonate or anabolic |
1-25DEXA T-Score Thresholds
Memory Hook:Remember: -1 and -2.5 are the threshold values. Above -1 = Normal, Between = Osteopenia, Below -2.5 = Osteoporosis.
BRADOsteoporosis Treatment Ladder
Memory Hook:BRAD treats osteoporosis: Bisphosphonates first, RANKL inhibitors, Anabolics for severe, D+Calcium always!
SHATTEREDSecondary Osteoporosis Causes
Memory Hook:SHATTERED bones - check for secondary causes in all young patients or severe disease!
Overview and Epidemiology
Why Osteoporosis Matters
Osteoporosis is the most common metabolic bone disease. Hip fracture has 20% 1-year mortality and 50% permanent disability. Every orthopaedic surgeon must screen, investigate, and treat.
Osteoporosis is a systemic skeletal disease characterized by low bone mass and microarchitectural deterioration, leading to increased bone fragility.
Epidemiology
- Prevalence: 200 million affected globally
- Gender: F greater than M (postmenopausal estrogen loss)
- Fractures: 1.5 million fragility fractures/year (US)
- Sites: Vertebra most common, hip most morbid
Osteoporosis is under-diagnosed and under-treated.
Burden of Disease
- Hip fracture mortality: 20% at 1 year
- Disability: 50% lose independence
- Cost: Enormous healthcare burden
- Second fracture risk: 20% within 1 year
Prevention and treatment save lives.
Pathophysiology and Bone Anatomy
Bone Remodeling
Bone is constantly remodeled by osteoclasts (resorption) and osteoblasts (formation). Osteoporosis results from imbalance favoring resorption. Peak bone mass is achieved by age 30 - after this, net bone loss begins.
Bone Physiology:
- Cortical bone: 80% of skeleton, slow turnover (dense outer layer)
- Trabecular bone: 20% of skeleton, rapid turnover (spongy inner)
- Remodeling cycle: 3-6 months (resorption then formation)
Pathophysiology of Osteoporosis:
- Estrogen deficiency (postmenopausal): Increased osteoclast activity
- Age-related: Reduced osteoblast function
- Secondary causes: Steroids, hyperthyroidism, hyperparathyroidism
Classification Systems
WHO DEXA Classification
| Category | T-Score | Interpretation | Action |
|---|---|---|---|
| Normal | At or above -1.0 | Normal bone density | Lifestyle measures, rescreen 5-10 years |
| Osteopenia | -1.0 to -2.5 | Low bone mass | Calculate FRAX, treat if high risk |
| Osteoporosis | At or below -2.5 | Osteoporosis | Pharmacotherapy indicated |
| Severe Osteoporosis | At or below -2.5 + fracture | Established osteoporosis | Consider anabolic therapy first |
T-score compares patient BMD to young adult (20-30 years) mean.
Clinical Assessment
History
- Prior fracture: Strongest risk factor
- Family history: Hip fracture in parent
- Medications: Steroids, aromatase inhibitors, PPI
- Lifestyle: Smoking, alcohol, low calcium intake
- Menopause: Early menopause (before 45)
- Secondary causes: Thyroid, parathyroid, RA
Comprehensive history identifies high-risk patients.
Examination
- Height loss: Greater than 2cm suggests vertebral fracture
- Kyphosis: Thoracic (dowager's hump)
- Rib-pelvis distance: Reduced in vertebral fractures
- Wall-occiput distance: For kyphosis
- Romberg's test: Balance for fall risk
- Timed Up and Go: Functional mobility
Examine for vertebral fractures and fall risk.
Vertebral Fractures Often Silent
Only 30% of vertebral fractures are clinically apparent. Height loss greater than 2cm or new kyphosis should prompt vertebral imaging (lateral spine X-ray or VFA on DEXA).
Investigations
Investigation Protocol
Gold standard for diagnosis. Measure femoral neck AND lumbar spine. Use lowest T-score. Femoral neck preferred for treatment decisions.
10-year fracture probability. Incorporates clinical risk factors. Treat if hip fracture risk greater than 3% or major osteoporotic fracture greater than 20%.
Exclude secondary causes. Calcium, phosphate, vitamin D, PTH, renal function, thyroid function, FBC, LFTs. Consider testosterone in men, celiac serology.
Lateral spine X-ray or VFA. If height loss greater than 2cm or kyphosis. Identifies prevalent vertebral fractures.
DEXA remains the gold standard for osteoporosis diagnosis.
Management Algorithm
Non-Pharmacological Management
Lifestyle Interventions
Calcium 1000-1200mg/day. Vitamin D 800-2000 IU/day. Food sources preferred. Supplement if inadequate.
Regular weight-bearing and resistance exercise. Improves BMD and reduces falls. Walking, dancing, strength training.
Fall prevention program. Home hazard assessment, vision check, medication review, balance training.
Smoking cessation. Limit alcohol (less than 2 drinks/day). Maintain healthy body weight.
Lifestyle measures are the foundation for ALL patients.
Surgical Technique
Cement Augmentation for Osteoporotic Bone
Screw Augmentation:
- PMMA cement around screws in osteoporotic bone
- Increases pullout strength 2-3x
- Useful in spine and periarticular fractures
Vertebroplasty/Kyphoplasty:
- Cement injection into vertebral body
- For painful vertebral compression fractures
- Kyphoplasty restores some height
Augmentation techniques improve fixation in osteoporotic bone.
Complications
Complications of Osteoporosis Treatment
| Complication | Risk | Management |
|---|---|---|
| ONJ (osteonecrosis of jaw) | 1 in 10000 to 1 in 100000 | Dental check before starting. Stop if surgery. |
| Atypical femoral fracture | Less than 1 in 1000 per year | Monitor for thigh pain. Drug holiday after 5 years. |
| GI upset (oral bisphosphonates) | 10-20% | Take fasting with water. Consider IV. |
| Denosumab rebound | Severe if stopped | NEVER stop abruptly. Transition to bisphosphonate. |
| Romosozumab CV risk | Signal in ARCH trial | Avoid if recent MI/stroke. |
ONJ and atypical fractures are rare but serious. Benefits of treatment far outweigh risks for patients with osteoporosis.
Postoperative Care
Post-Fracture Osteoporosis Management
Treat the fracture appropriately. Ensure adequate fixation in osteoporotic bone.
DEXA if not done. Laboratory workup for secondary causes. Refer to FLS if available.
Start bisphosphonate or anabolic. Zoledronic acid can be given 2 weeks post-fracture. Ensure adequate calcium and vitamin D.
Monitor DEXA at 2-3 years. Assess for new fractures. Consider treatment modification if not responding.
Fracture Liaison Service (FLS) is the evidence-based model ensuring all fracture patients are investigated and treated.
Outcomes and Prognosis
Fracture Risk Reduction:
- Bisphosphonates: 40-50% hip and vertebral fractures
- Denosumab: 40-70% fracture reduction
- Teriparatide: 65% vertebral, 50% non-vertebral
- Romosozumab: 70%+ vertebral fracture reduction
Prognosis After Hip Fracture:
| Outcome | Rate |
|---|---|
| 1-year mortality | 20% |
| Loss of independence | 50% |
| Permanent nursing home | 20% |
| Second hip fracture | 5-10% |
Early treatment prevents second fractures and mortality.
Evidence Base
- Alendronate vs placebo in postmenopausal women
- 50% reduction in hip fractures
- 47% reduction in vertebral fractures
- Benefit seen within 12-18 months
- Zoledronic acid vs placebo
- 70% reduction in vertebral fractures
- 41% reduction in hip fractures
- Annual IV infusion convenient
- Denosumab vs placebo
- 68% reduction in vertebral fractures
- 40% reduction in hip fractures
- 6-monthly injection
- Romosozumab vs alendronate
- 48% reduction in vertebral fractures vs active comparator
- Cardiovascular signal (MI, stroke)
- Most potent anabolic available
- FLS reduces re-fracture rate by 40%
- Cost-effective model of care
- Improves treatment initiation 3-fold
- Standard of care for fracture patients
Exam Viva Scenarios
Practice these scenarios to excel in your viva examination
Scenario 1: Post-Hip Fracture Management
"A 75-year-old woman is in hospital following ORIF for intertrochanteric hip fracture from a simple fall. How do you manage her osteoporosis?"
Scenario 2: DEXA Interpretation
"A 68-year-old woman has a DEXA showing T-score -2.1 at femoral neck and -2.8 at lumbar spine. She has no prior fractures. How do you interpret this and what is your management?"
Scenario 3: Denosumab Cessation
"A patient on denosumab for 3 years wants to stop treatment. Her last injection was 7 months ago (1 month overdue). What are your concerns and management?"
MCQ Practice Points
T-Score Threshold
Q: What T-score defines osteoporosis? A: At or below -2.5. T-score -1.0 to -2.5 is osteopenia. At or above -1.0 is normal.
First-Line Treatment
Q: What is the first-line pharmacological treatment for osteoporosis? A: Bisphosphonates (oral alendronate or IV zoledronic acid). 40-50% fracture reduction.
Denosumab Rebound
Q: What is the risk of stopping denosumab abruptly? A: Rebound vertebral fractures. Rapid bone loss occurs. MUST transition to bisphosphonate.
Hip Fracture Mortality
Q: What is the 1-year mortality after hip fracture? A: Approximately 20%. 50% lose independence. Second fracture risk is very high.
Drug Holiday Indication
Q: When should a bisphosphonate drug holiday be considered? A: After 5 years of oral or 3 years of IV therapy if not high-risk. Monitor for atypical fracture risk. Resume if new fracture.
FRAX Utility
Q: When should FRAX be used? A: In osteopenia (T-score -1.0 to -2.5) to determine treatment threshold. Treat if 10-year hip fracture risk at or above 3% or major osteoporotic fracture risk at or above 20%.
Australian Context
Australian Guidelines:
- RACGP Osteoporosis Guidelines 2017 (updated)
- NOF/ISCD: DEXA indications and interpretation
- PBS subsidized treatments available
PBS Subsidized Medications:
- Alendronate: PBS-listed for osteoporosis
- Zoledronic acid: PBS for established osteoporosis
- Denosumab: PBS after bisphosphonate failure or contraindication
- Teriparatide: PBS for severe osteoporosis with very low BMD or multiple fractures
- Romosozumab: PBS-listed for severe disease
Fracture Liaison Service:
- Best-practice model endorsed by ANZBMS
- Coordinated identification and treatment
- Reduces re-fracture by 40%
- Available in many Australian hospitals
Medicolegal Considerations:
- Failing to investigate/treat post-fragility fracture is negligent
- Document discussion of osteoporosis with all fracture patients
- FLS referral should be documented
Australian orthopaedic surgeons should ensure all fracture patients are investigated and treated for osteoporosis.
OSTEOPOROSIS
High-Yield Exam Summary
Diagnosis
- •DEXA T-score at or below -2.5 = osteoporosis
- •Fragility fracture = clinical osteoporosis
- •FRAX for treatment decision in osteopenia
- •Exclude secondary causes (bloods)
Treatment
- •Calcium 1000-1200mg + Vitamin D 800-2000 IU
- •Bisphosphonates first-line
- •Denosumab if bisphosphonate fails/contraindicated
- •Anabolics for severe disease
Key Drugs
- •Alendronate: Oral weekly
- •Zoledronic acid: IV yearly
- •Denosumab: SC 6-monthly (rebound risk)
- •Teriparatide/Romosozumab: Anabolic
Complications
- •ONJ: Rare (1 in 10000+)
- •Atypical fracture: Drug holiday after 5 years
- •Denosumab rebound: Must transition to bisphosphonate
- •GI upset with oral bisphosphonates (take upright)
Post-Fracture
- •All fragility fractures need treatment
- •FLS referral
- •Start treatment 2 weeks post-op
- •20% 1-year mortality hip fracture