Osteoporosis: Bone Density Loss, Fractures and Treatment

Osteoporosis: Bone Density Loss, Fractures and Treatment

Osteoporosis is a systemic skeletal disease characterised by low bone mass and deterioration of bone microarchitecture — together causing increased bone fragility and susceptibility to fractures from minimal trauma (a fall from standing height or less). It affects approximately 200 million people worldwide: 1 in 3 women and 1 in 5 men over 50 will experience an osteoporotic fracture in their lifetime.

The human and economic burden of osteoporosis is driven by fractures — particularly hip fractures. A hip fracture in an elderly person carries a 20–30% one-year mortality rate, and 50% of survivors do not regain their pre-fracture level of independence. Vertebral fractures cause chronic back pain, loss of height, and progressive kyphosis ("dowager's hump"), with each vertebral fracture adding cumulative disability.

Despite this, osteoporosis remains dramatically underdiagnosed and undertreated. Effective screening and treatments exist — most fractures in people with osteoporosis are preventable.

How Bone Works and Why It Fails

Bone is a dynamic, living tissue continuously being broken down (resorption by osteoclasts) and rebuilt (formation by osteoblasts) in a tightly regulated process called bone remodelling. Healthy bone maintains balance between resorption and formation, renewing bone tissue while preserving structural integrity.

Peak bone mass — the maximum bone density achieved in early adulthood (mid-20s) — is the major determinant of fracture risk in later life. It is influenced by genetics (up to 80%), physical activity, calcium and vitamin D intake, and hormonal status during growth.

From the mid-30s, bone density gradually declines. This accelerates dramatically in women at the menopause, when oestrogen loss removes a major inhibitor of osteoclast activity — resorption exceeds formation, and up to 20% of bone mineral density can be lost in the first 5–10 post-menopausal years. Men experience a slower, more gradual decline.

Bone Microarchitecture

Osteoporosis is not simply about mineral loss — the trabecular (spongy) bone architecture deteriorates: trabeculae thin, perforate, and disconnect. This structural disruption disproportionately weakens bone beyond what mineral density measurements alone capture.

Risk Factors

Major Risk Factors

• Age — risk of fracture doubles every 7–8 years after 50
• Female sex — women have lower peak bone mass and experience menopause-related bone loss; 75% of osteoporotic fractures occur in women
• Postmenopausal status — oestrogen deficiency is the dominant driver
• Prior fragility fracture — the most powerful predictor; a vertebral fracture is associated with an increased risk of further fractures, particularly soon after the initial fracture (the "imminent fracture" risk)
• Parental hip fracture — strong independent risk factor, reflecting genetic bone quality
• Low body weight (BMI <20) — less mechanical loading on bone; less adipose oestrogen production
• Smoking — directly impairs osteoblast function; nicotine and cadmium are toxic to bone
• Excessive alcohol (>3 units/day) — toxic to osteoblasts; impairs calcium absorption
• Glucocorticoid (steroid) use — the most common cause of secondary osteoporosis; prednisolone ≥5 mg/day for ≥3 months significantly increases fracture risk by impairing osteoblasts and increasing osteoclast activity; requires proactive bone protection from the outset

Secondary Causes of Osteoporosis

Always consider secondary causes — particularly in men, younger women, and those with low trauma fractures despite minimal risk factors:

• Hypogonadism (low testosterone/oestrogen): premature ovarian insufficiency, hypogonadotrophic hypogonadism, androgen deprivation therapy for prostate cancer, bilateral oophorectomy
• Malabsorption: coeliac disease, IBD, post-gastrectomy — impairs calcium and vitamin D absorption
• Hyperparathyroidism — PTH drives osteoclast activity
• Hyperthyroidism — excess thyroid hormone accelerates bone turnover
• Chronic liver disease — impaired vitamin D hydroxylation
• Chronic kidney disease — impaired calcium/phosphate metabolism; renal osteodystrophy
• Rheumatoid arthritis and inflammatory conditions — chronic inflammation and glucocorticoid use
• Type 1 diabetes — reduced bone quality independent of BMI
• Multiple myeloma — direct osteoclast activation by myeloma cells

Symptoms

Osteoporosis itself is asymptomatic — it is a "silent disease" until a fracture occurs. The first presentation is often an acute fracture.

Fragility Fractures

Defined as fractures resulting from a fall from standing height or less (minimal trauma) — an impact that would not normally break a healthy bone. Classic sites:

• Vertebral fractures — the most common osteoporotic fracture. May be painful (acute vertebral crush fracture: severe sudden back pain), or silent (detected incidentally on imaging). Multiple vertebral fractures cause loss of height (>4 cm), progressive kyphosis (thoracic forward curvature — "dowager's hump"), and reduced thoracic cage capacity. A vertebral fracture is associated with increased risk of further fractures, particularly soon after the initial fracture.
• Hip fracture — the most devastating; typically from a fall; requires surgical fixation (nail or hemiarthroplasty/total hip replacement); associated with significant mortality and permanent disability
• Distal radius (Colles') fracture — wrist fracture from falling onto an outstretched hand; common in middle-aged women; often the first osteoporotic fracture
• Proximal humerus and ankle — less common fragility fracture sites
• Rib fractures — from minimal trauma; may occur with coughing

Diagnosis

DEXA Bone Density Scan (Dual-Energy X-Ray Absorptiometry)

The gold standard investigation for osteoporosis. DEXA measures bone mineral density (BMD) at the lumbar spine and femoral neck, comparing the patient's BMD to a young adult reference population:

• T-score: standard deviations above/below the mean BMD of a healthy young adult at peak bone mass
  • T-score ≥-1.0: Normal
  • -2.5 < T-score < -1.0: Osteopenia (low bone density)
  • T-score ≤-2.5: Osteoporosis
  • T-score ≤-2.5 + fragility fracture: Severe/established osteoporosis

T-score is used for postmenopausal women and men ≥50. For younger adults, Z-score (comparison to age-matched peers) is used.

Who should have a DEXA scan? All postmenopausal women with risk factors; women ≥65; men ≥70; anyone with a fragility fracture; patients on long-term glucocorticoids; men with hypogonadism or other secondary causes.

FRAX Fracture Risk Assessment Tool

FRAX (Fracture Risk Assessment Tool) uses clinical risk factors ± BMD to calculate the 10-year probability of a major osteoporotic fracture (hip, clinical spine, forearm, or humerus) and hip fracture specifically. Used to guide treatment thresholds — many guidelines recommend treatment when 10-year major fracture probability exceeds 20%, or hip fracture probability exceeds 3%.

Laboratory Tests

To exclude secondary causes: calcium, phosphate, albumin, vitamin D (25-OH vitamin D), PTH, thyroid function (TSH), full blood count, renal and liver function, protein electrophoresis (to exclude myeloma), testosterone (in men).

Vertebral Fracture Assessment (VFA)

Low-dose lateral spinal X-ray (or DEXA-based VFA) to detect prevalent vertebral fractures — important because silent vertebral fractures dramatically increase subsequent fracture risk and change management.

Treatment

Calcium and Vitamin D

The foundation of all osteoporosis management:

• Calcium: 1000–1200 mg/day total (diet + supplement). Dietary sources (dairy, leafy greens, fortified foods) are preferred over supplements. Evidence on the cardiovascular effects of calcium supplements is mixed; whether supplementation is needed and the appropriate dose should be assessed with a clinician rather than using a fixed cardiovascular-risk threshold.
• Vitamin D: target 25-OH vitamin D >50 nmol/L. Most adults at risk require supplementation: 800–2000 IU (20–50 µg) vitamin D3 daily. Deficiency impairs calcium absorption and increases PTH-driven bone resorption.

Calcium and vitamin D alone do not reduce fractures in most community-dwelling adults — they are adjuncts to pharmacotherapy.

Antiresorptive Treatments

Bisphosphonates — first-line pharmacotherapy:

• Alendronate (weekly oral 70 mg), risedronate (dose and schedule depend on the product and indication; follow the prescribing clinician's instructions), zoledronate (annual IV infusion)
• Bind to hydroxyapatite at remodelling sites; taken up by osteoclasts; inhibit osteoclast enzyme farnesyl pyrophosphate synthase, causing osteoclast apoptosis
• Reduce vertebral fracture risk by 40–70%, hip fracture by 40–50%
• Treatment duration: typically 5 years oral / 3 years IV (zoledronate), then reassess; drug holiday after 5 years for lower-risk patients (drug persists in bone)
• Side effects: GI (oral bisphosphonates — take on empty stomach, remain upright 30 min), flu-like symptoms (IV zoledronate), rare: osteonecrosis of the jaw (ONJ; risk varies with treatment exposure and individual factors), atypical femur fracture (rare with long-term use)

Denosumab (Prolia) — 60 mg subcutaneous injection every 6 months:

• Monoclonal antibody against RANKL (the signalling molecule required for osteoclast formation); potently inhibits osteoclast activity
• Reduces vertebral fracture by 68%, hip by 40%
• The US FDA has a boxed warning for severe hypocalcaemia in advanced chronic kidney disease, particularly in people on dialysis or with CKD-related mineral and bone disorder. Use in these patients requires specialist assessment, appropriate calcium/vitamin D management and calcium monitoring
• Important: stopping or delaying denosumab can cause rebound bone loss and vertebral fractures. Do not stop or delay it without a clinician-agreed follow-on treatment plan; the choice and timing of another antiresorptive depend on the last injection, kidney function and individual risk

Anabolic (Bone-Building) Treatments

For severe osteoporosis (very low BMD, multiple vertebral fractures) — agents that stimulate new bone formation rather than merely slowing resorption:

Teriparatide (Forteo) — recombinant parathyroid hormone (PTH 1-34); 20 µg subcutaneous daily injection for 24 months; reduces vertebral fracture by 65%, non-vertebral by 53%; increases spine BMD by 8–10%; an anabolic treatment option for selected patients at very high fracture risk; then followed by antiresorptive therapy to consolidate gains.

Romosozumab (Evenity) — monoclonal antibody against sclerostin; 210 mg monthly SC injection for 12 months; dual action (anabolic + antiresorptive); superior to alendronate in very high-risk patients. Cardiovascular risk must be assessed before treatment. The U.S. label excludes starting treatment after a heart attack or stroke in the past year and requires weighing other cardiovascular risks; the prescribing clinician must follow the applicable local label. The course is then followed by denosumab or alendronate.

Abaloparatide — PTHrP analogue; similar to teriparatide; available in some countries.

Hormone Replacement Therapy (HRT)

Oestrogen prevents postmenopausal bone loss and reduces fracture risk (30–50% for vertebral and non-vertebral fractures). Recommended primarily for management of menopausal symptoms in women at increased fracture risk; most effective within 10 years of menopause. Benefits persist only while taking HRT; fracture protection wanes after stopping.

Fall Prevention

Given that most osteoporotic fractures are precipitated by falls, fall prevention is as important as bone protection:

• Assessment of fall risk factors: strength and balance, medications (sedatives, antihypertensives, diuretics causing orthostatic hypotension), vision, footwear, and home hazards
• Exercise: balance and strength training (Tai chi, resistance training, yoga) significantly reduce falls
• Hip protectors: external padding over the greater trochanter reduces hip fracture risk in residential care settings

Osteoporosis Care in China

China's bone health and osteoporosis centres offer:

• DEXA bone densitometry: T-score and Z-score assessment of spine and hip; vertebral fracture assessment
• FRAX-guided treatment planning: fracture risk stratification with local Chinese FRAX calibration; secondary cause screen
• Medicine availability: Ask the treating hospital to confirm the specific medicine, its locally approved indication and current supply. Availability of the medicines listed in this guide, including any locally made alternative, is not guaranteed.
• Annual IV zoledronate infusions: outpatient infusion service; particularly suited for patients with adherence challenges or GI intolerance of oral bisphosphonates
• Spinal fracture management: pain control, assessment and an individual care plan. Vertebroplasty or kyphoplasty is not a routine response to an acute painful fracture; evidence of benefit is inconsistent, and any use requires specialist selection after assessing persistent severe pain, imaging findings, prior treatment and procedural risks.
• Cost: care in China is generally less expensive than UK private treatment, but the hospital prices each case individually — ask us for the written quote before you commit.
• Full English care navigation from assessment through treatment and monitoring

Contact a PriumCare care navigator to arrange a bone density assessment, FRAX calculation, or osteoporosis treatment review.

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Medical content based on MSD Manuals and international osteoporosis guidelines (IOF, NOGG, AACE). Evidence reviewed 2025.

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Targeted editorial source check — 26 October 2026: Only the passages on recurrent-fracture risk, T-score endpoints, jaw osteonecrosis risk and denosumab kidney safety/discontinuation planning were checked against NOGG fracture-risk guidance, NIAMS T-score information, ISCD adult positions, NOGG adverse-effect guidance, the US FDA denosumab warning and NOGG denosumab guidance. This is not a whole-article medical review, adds no named clinical reviewer and retains the original publication date.

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Targeted editorial source check — 26 October 2026: Only the calcium-supplement cardiovascular-risk wording, the non-ranked role of teriparatide, the cardiovascular selection warning for romosozumab, and the removal of an unverified blanket medicine-availability promise were checked against NIH calcium information, NOGG treatment guidance and U.S. romosozumab prescribing information. U.S. labeling is identified as such and does not establish local approvals or hospital supply. This is not a whole-article medical review, adds no named clinical reviewer and retains the original publication date.

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Targeted editorial source check — 26 October 2026: Only the FRAX attribution and the selection limits for vertebroplasty or kyphoplasty were checked against the University of Sheffield FRAX information, NOGG symptomatic-fracture guidance and NICE TA279 recommendations. These sources do not establish availability or individual procedural suitability at a hospital in China. This is not a whole-article medical review, adds no named clinical reviewer and retains the original publication date.

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Targeted editorial source check — 26 October 2026: Only the ambiguous risedronate dose/schedule phrase was checked against U.S. product labeling published by NLM. No new dosing regimen is prescribed here; the applicable product label and prescribing clinician govern. This is not a whole-article medical review, does not verify other retained statistics or treatment statements and retains the original publication date.