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
Clinical 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
| N | Normal T-score at or above -1.0 |
| OP | Osteopenia T-score -1.0 to -2.5 |
| OS | Osteoporosis T-score at or below -2.5 |
| N | Normal T-score at or above -1.0 |
| OP | Osteopenia T-score -1.0 to -2.5 |
| OS | Osteoporosis T-score at or below -2.5 |
Hook:Remember: -1 and -2.5 are the threshold values. Above -1 = Normal, Between = Osteopenia, Below -2.5 = Osteoporosis.
BRADOsteoporosis Treatment Ladder
| B | Bisphosphonates First-line: alendronate, zoledronic acid |
| R | RANKL inhibitor Denosumab (second-line, rebound risk) |
| A | Anabolics Teriparatide, romosozumab (severe disease) |
| D | Supplements Calcium + Vitamin D (all patients) |
| B | Bisphosphonates First-line: alendronate, zoledronic acid | A | Anabolics Teriparatide, romosozumab (severe disease) |
| R | RANKL inhibitor Denosumab (second-line, rebound risk) | D | Supplements Calcium + Vitamin D (all patients) |
Hook:BRAD treats osteoporosis: Bisphosphonates first, RANKL inhibitors, Anabolics for severe, D+Calcium always!
SHATTEREDSecondary Osteoporosis Causes
| S | Steroids Glucocorticoid-induced |
| H | Hyperthyroidism/Hyperparathyroidism Endocrine causes |
| A | Alcohol/Aromatase inhibitors Lifestyle and drugs |
| T | Thin (BMI less than 19) Low body weight |
| T | Testosterone deficiency Male hypogonadism |
| E | Early menopause Before age 45 |
| R | Renal/GI disease Malabsorption, CKD |
| E | Erosive/RA Inflammatory arthritis |
| D | Diabetes Type 1 Although BMD may be normal |
| S | Steroids Glucocorticoid-induced | T | Thin (BMI less than 19) Low body weight | R | Renal/GI disease Malabsorption, CKD |
| H | Hyperthyroidism/Hyperparathyroidism Endocrine causes | T | Testosterone deficiency Male hypogonadism | E | Erosive/RA Inflammatory arthritis |
| A | Alcohol/Aromatase inhibitors Lifestyle and drugs | E | Early menopause Before age 45 | D | Diabetes Type 1 Although BMD may be normal |
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.
Differential Diagnosis of Low Bone Mass / Fragility Fracture
Low BMD or an apparently fragility fracture is not always primary osteoporosis. Distinguish these mimics — they change management entirely.
Distinguishing Osteoporosis from Mimics
| Condition | Key discriminator | Calcium / Phosphate / ALP | Action |
|---|---|---|---|
| Osteoporosis | Low BMD, normal biochemistry, fragility fracture | Normal Ca, PO4, ALP | Antiresorptive or anabolic |
| Osteomalacia | Bone pain, proximal myopathy, Looser zones | Low/normal Ca, low PO4, high ALP, low vitamin D | Correct vitamin D / phosphate first |
| Primary hyperparathyroidism | Cortical (forearm) bone loss, stones, fatigue | High Ca, low PO4, high PTH | Treat parathyroid disease |
| Multiple myeloma / metastasis | Lytic lesions, pathological fracture, weight loss | High Ca, high ALP if blastic, raised ESR/paraprotein | Biopsy / oncology workup |
| Paget disease | Bone deformity/expansion, isolated high ALP | Normal Ca/PO4, markedly high ALP | Bisphosphonate for active disease |
| Osteogenesis imperfecta | Young patient, blue sclerae, family history | Normal biochemistry | Genetic / specialist; bisphosphonates |
Always Exclude Osteomalacia and Myeloma
Before labelling low BMD as osteoporosis, check biochemistry. A high ALP, low phosphate or high calcium should redirect the workup. An unexpected pathological fracture in a patient with weight loss demands exclusion of myeloma and metastasis.
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.
Controversies and Areas of Uncertainty
Anabolic-first vs antiresorptive-first
Trials (ARCH, and teriparatide-then-antiresorptive data) and ESCEO/AACE favour an anabolic-first sequence in very high risk patients, because gains are larger when an anabolic precedes an antiresorptive. The threshold defining 'very high risk', and cost, remain debated.
Optimal denosumab exit strategy
Rebound after stopping denosumab is established, but the best transition (timing of zoledronic acid, single vs repeated dosing, role of bone-turnover markers) is not fully settled. Most guidance gives a bisphosphonate around 6 months after the last denosumab dose.
Drug holidays
Bisphosphonate holidays balance falling atypical-fracture risk against rising fracture risk. There is no validated tool to time resumption; decisions rest on BMD, fracture history and clinical judgement. Denosumab and anabolics have no holiday concept.
Calcium/vitamin D supplementation
Routine supplementation in community-dwelling, replete adults gives uncertain fracture benefit and a debated cardiovascular/renal-stone signal. Value is clearest in deficient or institutionalised populations and as an adjunct to active drug therapy.
Treating osteopenia and the very elderly
FRAX-guided treatment of osteopenia is widely endorsed, yet the cost-effective threshold varies by country. Evidence in the very old and those with limited life expectancy is thinner, favouring agents with rapid benefit such as zoledronic acid.
Romosozumab cardiovascular signal
The excess cardiovascular events versus alendronate in ARCH (not seen versus placebo in FRAME) remain incompletely explained. Regulators advise avoiding romosozumab within 12 months of MI or stroke; the underlying mechanism is unresolved.
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
- 2027 postmenopausal women with low femoral-neck BMD and at least one existing vertebral fracture; alendronate vs placebo over 36 months
- New morphometric vertebral fracture 8.0% vs 15.0% (RR 0.53)
- Hip fracture relative hazard 0.49 and wrist 0.52
- Any clinical fracture relative hazard 0.72
- 7765 women (mean age 73); once-yearly IV zoledronic acid 5mg vs placebo over 3 years
- Morphometric vertebral fracture reduced 70% (3.3% vs 10.9%; RR 0.30)
- Hip fracture reduced 41% (1.4% vs 2.5%; HR 0.59)
- Serious atrial fibrillation more frequent with zoledronic acid (50 vs 20 patients)
- 7868 women (age 60-90, T-score -2.5 to -4.0); denosumab 60mg SC 6-monthly vs placebo over 36 months
- New vertebral fracture reduced 68% (2.3% vs 7.2%; RR 0.32)
- Hip fracture reduced 40% (0.7% vs 1.2%; HR 0.60)
- Nonvertebral fracture reduced 20%; no ONJ cases in the pivotal trial
- 4093 postmenopausal women with osteoporosis and a fragility fracture; 12 months romosozumab then alendronate vs alendronate throughout
- New vertebral fracture at 24 months reduced 48% (6.2% vs 11.9%)
- Hip fracture reduced 38% (2.0% vs 3.2%); clinical fracture reduced 27%
- More adjudicated serious cardiovascular events in year 1 with romosozumab (2.5% vs 1.9%)
- 1637 postmenopausal women with prior vertebral fractures; teriparatide (PTH 1-34) 20 or 40mcg daily vs placebo (median 21 months)
- New vertebral fracture 5% (20mcg) vs 14% placebo (RR 0.35)
- New nonvertebral fragility fracture reduced ~50% (RR 0.47)
- Lumbar spine BMD increased markedly; only minor side effects (nausea, headache)
- 74 controlled studies (16 RCTs, 58 observational) of FLS vs usual care
- BMD testing 48.0% vs 23.5%; treatment initiation 38.0% vs 17.2%; adherence 57.0% vs 34.1%
- Re-fracture absolute risk reduced ~5 percentage points (13.4% to 6.4% unweighted)
- Mortality reduced ~3 percentage points (15.8% to 10.4% unweighted)
Exam Viva Scenarios
Use these scenarios to practise clinical reasoning and management decisions
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%.
Guidelines, Registries & Global Practice
Global Epidemiology:
- An estimated 500 million people worldwide have osteoporosis; roughly 1 in 3 women and 1 in 5 men over 50 will sustain a fragility fracture
- Lifetime hip-fracture risk approaches that of breast cancer in women; the global hip-fracture burden is projected to rise sharply with population ageing, with the largest increases in Asia
- Bone mineral density thresholds (T-score) are universal, but fracture incidence varies by region (higher in Northern Europe/Scandinavia, lower in parts of Africa and Asia), reflecting genetics, body habitus, vitamin D status and fall rates
Major Guidelines — Side by Side:
| Body | Treatment threshold | First-line | Notable position |
|---|---|---|---|
| AACE/ACE & Endocrine Society (US) | T-score at or below -2.5, prior hip/vertebral fracture, or high FRAX | Bisphosphonate; anabolic first if very high risk | Risk-stratified ('very high risk') pathway favouring anabolic-first sequencing |
| NOGG / RCP (UK) | FRAX-based intervention thresholds (age-dependent) | Oral bisphosphonate (alendronate/risedronate) | FRAX integrated into thresholds; anabolic for very high risk |
| NICE (UK) | FRAX or QFracture above intervention threshold | Alendronate / risedronate | Health-economic appraisal drives sequencing; romosozumab via technology appraisal |
| ESCEO / IOF (Europe) | FRAX-based; 'very high risk' category | Bisphosphonate or anabolic by risk | Champions anabolic-first then antiresorptive in very high risk |
| AOA / AOTrauma | Fragility fracture = treat | Antiresorptive plus FLS pathway | Surgeon-led case-finding and bone health after fracture |
Across all major bodies the core message is consistent: a fragility fracture warrants treatment irrespective of BMD, FRAX (or QFracture) guides therapy in osteopenia, and bisphosphonates remain first-line for most, with anabolic-first sequencing reserved for very high risk.
Registry & Audit Evidence:
- National hip-fracture registries/audits (UK National Hip Fracture Database, Australian and New Zealand Hip Fracture Registry, and similar programmes) consistently link timely surgery, orthogeriatric co-care and bone-health assessment to lower mortality and re-fracture
- Capture–the–Fracture (IOF) benchmarks FLS programmes internationally
High- vs Limited-Resource Practice:
- Well-resourced settings: DEXA, FRAX, FLS, and access to denosumab and anabolics (teriparatide, romosozumab) are standard
- Limited-resource settings: DEXA may be scarce — diagnosis relies on fragility-fracture history and clinical risk; generic oral/IV bisphosphonates and calcium/vitamin D form the backbone; FRAX can be used without BMD input
Clinical Governance:
- Failure to investigate and treat after a fragility fracture is a recognised care gap and a medicolegal exposure worldwide
- Document the osteoporosis discussion and FLS/bone-health referral for every fragility-fracture patient
OSTEOPOROSIS
Clinical 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