Osteoporosis

Overview

•Systemic skeletal disease - low bone mineral density (BMD) + deterioration of bone microarchitecture → increased fragility and fracture risk

•Largely asymptomatic until a fragility fracture occurs - risk stratification and proactive screening are central

•~2 million affected in the UK; ~300,000 fragility fractures/year; hip fracture 1-year mortality ~30%

Risk factors

Key risk factors (assessed by FRAX tool)

Postmenopausal oestrogen deficiency

Age (peak bone mass lost after ~30s)

Long-term corticosteroids (prednisolone ≥7.5 mg/day >3 months)

Female sex / low BMI

Previous fragility fracture

Parental hip fracture

Smoking / excess alcohol

Hypogonadism (incl. men)

Hyperparathyroidism / hyperthyroidism

Malabsorption (coeliac, IBD)

Chronic kidney or liver disease

Rheumatoid arthritis / prolonged immobility

⚠️

Corticosteroid-induced osteoporosis is the most common secondary cause. Consider bone protection when starting prednisolone ≥7.5 mg/day for >3 months - do not wait for a fracture.

Presentation

•Fragility fracture - fracture from fall from standing height or less (or no identifiable trauma)

•Vertebral compression fracture - most common site; may be silent or cause acute/chronic back pain, progressive kyphosis ('dowager's hump'), height loss

•Hip fracture - groin/proximal thigh pain, inability to weight bear, shortened externally rotated leg

•Distal radius (Colles') fracture - fall onto outstretched hand

•Up to two-thirds of vertebral fractures are clinically silent - discovered incidentally on imaging

Investigations

•FRAX tool - estimates 10-year major osteoporotic fracture risk; determines who needs DEXA scanning (can be used without BMD)

🏆 Gold standard

•DEXA scan - measures BMD at lumbar spine and femoral neck; generates T-score and Z-score; low radiation

•Bloods to exclude secondary causes: serum calcium, vitamin D (25-OH), renal function (eGFR), FBC, LFTs, TFTs, PTH, testosterone (men)

•Spinal X-ray - to identify prevalent vertebral fractures

⚠️

Check eGFR before starting bisphosphonates - contraindicated if eGFR <35 mL/min. Correct vitamin D deficiency before or alongside treatment to avoid hypocalcaemia.

Management

•Lifestyle: weight-bearing exercise, smoking cessation, alcohol reduction, dietary calcium, adequate sunlight; falls risk assessment (polypharmacy, visual impairment, home hazards)

•Calcium (1000-1200 mg/day) + vitamin D (800 IU/day) supplementation alongside bisphosphonates if intake/levels insufficient - take at a different time of day from bisphosphonates

🥇 First-line

•alendronate 70 mg orally once weekly - oral bisphosphonate; reduces vertebral fracture risk ~50%, hip fracture risk ~40%

•First-line alternative: risedronate 35 mg orally once weekly - if alendronate not tolerated (upper GI intolerance)

🥈 Second-line

•zoledronic acid 5 mg IV once yearly - for those unable to tolerate/adhere to oral bisphosphonates

•denosumab 60 mg SC every 6 months - anti-RANK-L monoclonal antibody; used when bisphosphonates contraindicated (e.g. renal impairment)

🥉 Third-line

•teriparatide 20 micrograms SC daily (up to 24 months) - anabolic (stimulates osteoblasts); severe osteoporosis or fracture on first-line therapy

•romosozumab - anti-sclerostin antibody; dual anabolic and antiresorptive; NICE approved for postmenopausal women at high fracture risk

🎯

Oral bisphosphonate rules: take on an empty stomach with a full glass of water, at least 30 minutes before food/drink/other medications, remain upright for ≥30 minutes after. Failure = oesophageal ulceration and poor absorption.

Complications

•Osteonecrosis of the jaw (ONJ) - rare; exposed oral bone that fails to heal; risk low with oral bisphosphonates, higher with IV (oncology doses); annual dental review advised

•Atypical femoral fractures - rare; long-term bisphosphonate use (>5 years); subtrochanteric/femoral shaft stress fractures; prodrome of thigh pain

•Hypocalcaemia - after denosumab or IV bisphosphonates, especially if vitamin D deficiency uncorrected

•Oesophageal ulceration - oral bisphosphonates if administration rules not followed

Classification (WHO T-score)

Classification	T-score
Normal	≥ -1.0
Osteopenia	-1.0 to -2.5
Osteoporosis	≤ -2.5
Severe osteoporosis	≤ -2.5 + fragility fracture

•Z-score compares to age/sex-matched population - Z-score below -2.0 suggests a secondary cause

Follow-up and treatment duration

•Repeat DEXA after 2 years of treatment to assess response

•Bisphosphonate therapy: typically 5 years (oral) or 3 years (IV zoledronic acid), then consider a drug holiday in lower-risk patients

•Denosumab must NOT be stopped abruptly - causes rapid bone loss and rebound vertebral fractures; plan transition to a bisphosphonate when stopping

📌

Any patient aged ≥50 with a fragility fracture should be referred to a Fracture Liaison Service (FLS) for systematic assessment and treatment.