Osteoporosis

Meet the patient

A 72-year-old woman is admitted after slipping on a wet bathroom mat and landing on her hip — she cannot weight-bear, and the X-ray shows an intertrochanteric fracture. She had a wrist fracture at 64 that was "just plastered", takes no bone medication, and has lost five centimetres of height over the last decade. Her bloods come back normal: calcium 2.38, phosphate 1.1, ALP 95.[1][5]

The single question that must be answered before she leaves hospital is the question that defines this whole disease: has anyone ever measured her bone, and is she on a bisphosphonate yet? The wrist fracture eight years ago was her first warning, missed. Everything below exists to make sure the second fracture never happens — and the single zoledronate infusion given within 90 days of this hip repair is the intervention that will cut her mortality by 28 percent.[1][5]

What osteoporosis actually is — porous bone, the T-score, and the fracture that trumps the number

Osteoporosis is the most common metabolic bone disease, and its entire clinical importance is its fractures — the bone itself is painless until it breaks. It is a progressive systemic skeletal disorder of low bone mass and microarchitectural deterioration that raises bone fragility and fracture risk; the fractures cluster at the hip, vertebrae and distal forearm, and they carry major morbidity, mortality and cost, especially in older adults. So management is preventive end to end: find high-risk bone early with DEXA and FRAX, treat it, and stop the next fracture before it starts.[1]

The operational WHO threshold is the DEXA T-score — the number of standard deviations the patient's bone mineral density sits below the young-adult healthy mean. Osteoporosis is a T-score of minus 2.5 or less at the femoral neck, total hip or lumbar spine; osteopenia is minus 1.0 to minus 2.5; normal is minus 1.0 or higher. Premenopausal women and men under 50 use the Z-score (age- and sex-matched) instead. The threshold examiners love to probe is the override clause: a low-trauma fracture of the hip or spine establishes osteoporosis regardless of the T-score — so a patient in the osteopenic band who has already fractured is treated as having the disease, not watched.[1][2]

The consultant confession: I have seen too many patients told their DEXA was "only osteopenic, come back in two years" — having already fractured. The T-score is a probability tool, not a gatekeeper. The fracture is the disease.[1]

The other defining feature is biochemical silence. In osteoporosis the serum calcium, phosphate and alkaline phosphatase are normal — and that one fact does more differential-diagnosis work than any scan. A raised calcium means malignancy or hyperparathyroidism; a raised ALP means osteomalacia, Paget or malignancy; a low calcium means osteomalacia or vitamin D deficiency. Normal across the board, plus a fragility fracture, is osteoporosis until proven otherwise.[1]

Two axes classify it, and only one is useful at the bedside. The historical pathophysiological split separates type 1 (postmenopausal) — oestrogen-driven, high-turnover, trabecular, vertebral and wrist fractures in women aged 50 to 70 — from type 2 (senile) — low-turnover, cortical and trabecular, hip and pelvic fractures in men and women over 70. The axis that actually changes management is primary versus secondary: roughly half of women and the majority of men with a fragility fracture have an identifiable secondary driver, so a structured hunt is mandatory in every new diagnosis.[1]

[1]

How common, who breaks, and where to cast the net

Osteoporosis is silent, common, and astonishingly asymmetric across sex. An estimated 200 million people live with it worldwide — an osteoporotic fracture happens roughly every 3 seconds — and the lifetime risk after 50 is about one in three women and one in five men. Hip-fracture incidence climbs exponentially in women after 50 and in men after 70, and as populations age the global burden is projected to roughly double.[1]

[1]

The burden lands hardest on the hip. Of an estimated 9 million osteoporotic fractures a year, about 1.6 million are hip fractures, projected to rise sharply as Asia ages. Hip fracture consumes a major share of every developed health system's orthopaedic and rehabilitation budget, and the loss of independence afterwards is the single largest driver of new nursing-home admissions in older women. Women dominate the postmenopausal cohort, but men die more often after a hip fracture — partly because the diagnosis is never made and no bone therapy is ever started.[1]

Risk factors split into fixed and modifiable or iatrogenic, and the modifiable list is the one an examiner wants verbatim. Fixed: age, female sex, menopause, parental history of hip fracture, low body mass index, and white or Asian ethnicity. The actionable, secondary drivers are the list to reel off: oral glucocorticoids, hypogonadism (premature menopause, anti-androgen therapy, hyperprolactinaemia), hyperthyroidism, primary hyperparathyroidism, chronic kidney disease, malabsorption (coeliac, post-gastrectomy, bariatric), chronic liver disease, rheumatoid arthritis, low calcium and vitamin D, immobility, and low BMI.[1][2]

Why bone breaks — RANKL, OPG, and the oestrogen that holds the brake

Bone is not inert — it is continually remodelled, and osteoporosis is a remodelling imbalance where resorption outruns formation. Two cell lineages do the work in coupled basic multicellular units: osteoclasts (multinucleated, haematopoietic-derived) resorb old bone, and osteoblasts (mesenchymal-derived) lay down new osteoid that then mineralises. Over any cycle in osteoporosis, resorption exceeds formation, the net balance is negative, trabeculae thin and perforate, cortex becomes porous, and bone strength — which depends on density and quality (architecture, mineralisation, microdamage) — falls until a minor load snaps it.[1]

Etymology for viva gold: osteo is Greek for "bone", poros for "passage" or "pore" — osteoporosis is literally "porous bone". Drop that and the examiner knows you have read past the headline.[1]

The molecular control of the balance is the RANK / RANKL / OPG axis, and it is the single most examinable pathway in bone. RANKL (receptor activator of nuclear factor kappa-B ligand), expressed by osteoblasts and stromal cells, binds RANK on the osteoclast precursor and drives its differentiation, activation and survival. The decoy receptor osteoprotegerin (OPG), also made by osteoblasts, mops up RANKL and blocks it, braking resorption. After the menopause, oestrogen deficiency removes the brake: RANKL and the pro-resorptive cytokines (IL-1, IL-6, TNF-alpha) rise while OPG falls, osteoclasts are recruited in droves, and resorption accelerates — producing high-turnover, type 1 (postmenopausal) osteoporosis with selective trabecular loss.[1]

A remodelling cycle runs a fixed sequence — activation, resorption, reversal, formation, mineralisation, resting — normally ending in balanced repair. The conductor is the osteocyte, the most abundant and long-lived cell in bone, exquisitely mechanosensitive through its lacuno-canalicular network: load it and it promotes formation; unload it (immobility, paralysis, weightlessness) and it signals for resorption. The molecular link from sensing to building is Wnt signalling, which osteocytes restrain by secreting sclerostin (SOST) and Dickkopf-1. Ageing raises sclerostin, osteoblast formation declines, osteocytes senesce and die, and each cycle underfills its resorption cavity — the lesion of low-turnover, type 2 (senile) osteoporosis and the hip and pelvic fractures of advanced age.[1]

The same final common pathway is amplified by every secondary driver. Glucocorticoids suppress osteoblast and osteocyte survival and raise resorption; hyperthyroidism and excess thyroid replacement accelerate turnover; hyperparathyroidism drives osteoclast-mediated resorption directly; hypogonadism removes the same oestrogen or testosterone brake as the menopause; immobility unloads the osteocyte. Knowing the axis is knowing the drugs: bisphosphonates and denosumab both blunt resorption, while teriparatide and romosozumab push the formation side.[1]

[6]

The silent disease — how the patient actually looks

Osteoporosis produces no symptoms until bone breaks — and the break is almost always from a trivial fall. Many patients are flagged first by a DEXA done for risk factors; far too many are flagged only by the first fracture. The presentations cluster into three patterns, sometimes with the chronic deformity of accumulated vertebral collapse.[1]

Vertebral (fragility) fractures are the commonest. About two-thirds are clinically silent and are found incidentally on chest or abdominal imaging; the rest present with acute or subacute mid- to lower-thoracic and upper-lumbar back pain after minimal or no trauma — often just bending, lifting or coughing — that is local and mechanical, eased by rest and worse sitting forward. Multiple wedge compressions shorten and angulate the spine: loss of height over 4 cm, a progressive thoracic kyphosis (the dowager's hump), a protuberant abdomen where the rib margin meets the pelvic brim, and in severe cases a restrictive ventilatory defect. A painful vertebral fracture is managed with stepped analgesia, early mobilisation, and — for persistent severe pain — percutaneous vertebroplasty or kyphoplasty.[1]

Hip fractures present after a fall from standing height with groin pain, an externally rotated and shortened leg, and inability to weight-bear — a surgical emergency under a combined orthogeriatric model (see below). Distal forearm (Colles) fractures classically follow a fall onto an outstretched hand in a postmenopausal woman — the median age is younger than for hip fracture, and it is often the first hint that the skeleton is failing.[1]

[1]

The unifying clue across all of them is low-energy trauma — a fall from standing height or less, or a force that would not break a healthy bone. Any fracture sustained in such circumstances, at any age, establishes osteoporosis until proven otherwise and triggers the work-up below.[1]

Split the mimics — the differential face-off

The decisive discriminator is almost always a biochemical or radiological abnormality that osteoporosis lacks. Because osteoporosis is biochemically silent and presents with fracture or low density, the differential is the set of conditions that also produce bone pain, fracture or low bone mass:[1]

[1]

The one-line discriminator beneath: in osteoporosis the serum calcium, phosphate and ALP are normal; raised calcium is malignancy or hyperparathyroidism; raised ALP is osteomalacia, Paget or malignancy; low calcium is osteomalacia or vitamin D deficiency. And always think myeloma in any older patient with a fragility fracture — check the full blood count, renal function, calcium, and serum and urine protein electrophoresis.[1]

The bedside round — height, hips, and the secondary-cause hunt

Bedside assessment rarely makes the diagnosis; it confirms the fracture pattern, sizes up fall risk, and hunts the secondary driver. Three aims, in this order:[1][2]

• Measure height every visit. Loss of more than 4 cm from the young-adult peak is a sensitive trigger to image the thoracolumbar spine for occult vertebral fractures.
• Weigh and calculate BMI. A BMI under 21 to 22 is an independent risk factor and a FRAX input.
• Examine for kyphosis (wall-to-occiput gap), proximal muscle weakness (a proximal myopathy whispers osteomalacia, not osteoporosis), and focal spinal tenderness (vertebral fracture — or, if constant and progressive, malignancy).
• Screen the secondary drivers at the bedside — thyrotoxicosis or hypothyroidism, Cushing syndrome (striae, bruising, central obesity, proximal myopathy), hypogonadism in men (loss of secondary sexual hair, small testes), and chronic liver or renal disease.[1][2]

A prior fragility fracture is at once the strongest risk factor and a diagnostic event — examine for old fractures at the wrist, hip, spine, proximal humerus and pelvis, and corroborate with prior imaging. The patient who has already fractured is the one most likely to fracture again, which is why the highest-yield intervention in the field is finding her.[1]

DEXA, FRAX and the secondary hunt — the fixed diagnostic ladder

Investigation answers four questions: how dense is the bone, what is the absolute fracture risk, is there an occult vertebral fracture, and is there a secondary cause? Run them as a set.[2]

DEXA of the lumbar spine, total hip and femoral neck is the gold standard, reported as the T-score (standard deviations below the young-adult mean) in adults over 50 and the Z-score (age- and sex-matched) in premenopausal women and men under 50. The WHO thresholds, reproduced exactly: osteoporosis equals minus 2.5 or less; osteopenia equals minus 1.0 to minus 2.5; normal equals minus 1.0 or higher; severe (established) osteoporosis equals minus 2.5 or less plus a fragility fracture. DEXA is reported per-site because arthritis, aortic calcification or an existing vertebral fracture can artefactually raise the spine reading, so use the lowest of femoral neck, total hip and spine.[1]

[2]

FRAX turns the risk factors into a 10-year fracture probability. It integrates age, sex, BMI, prior fragility fracture, parental hip fracture, current smoking, glucocorticoid use, rheumatoid arthritis, secondary causes, and alcohol 3 or more units daily — with or without femoral-neck BMD — into the 10-year probability of hip fracture and of a major osteoporotic fracture (clinical spine, hip, forearm, proximal humerus). FRAX earns its keep in the osteopenic range, where it decides who to treat, and it is calibrated to national epidemiology. Remember its blind spot: it takes yes/no inputs and does not accumulate dose, so it underestimates risk in heavy smokers, high-dose steroids and the very-high-risk patient.[10][2]

Vertebral fracture assessment (VFA) runs on the DEXA machine at the time of BMD, or as a lateral thoracolumbar spine X-ray, to catch the morphometric vertebral fractures that are clinically silent but, once present, establish the diagnosis and independently raise future fracture risk. Indications: height loss over 4 cm, historical height loss over 6 cm, recent non-traumatic back pain, and osteopenia with age over 70 in women or 80 in men.[2]

Screen for a secondary cause in every new diagnosis — the panel that pays for itself: full blood count and ESR, serum calcium, phosphate, albumin and ALP, renal and liver function, TSH, 25-hydroxy vitamin D, and serum testosterone in men. Add when the picture demands it: intact PTH, 24-hour urinary calcium (hypercalciuria or malabsorption), serum and urine protein electrophoresis with serum free light chains (myeloma), coeliac serology (tissue transglutaminase IgA) in unexplained or low-BMI disease, a morning cortisol or overnight dexamethasone suppression (Cushing), gonadotrophins (FSH, LH) to characterise hypogonadism, and bone turnover markers (CTX, P1NP) as a baseline and adherence check. Bone biopsy is reserved for atypical presentation or suspected osteomalacia.[1][2]

One caveat worth stating: plain X-rays confirm a fracture but do not measure density. Bone must lose roughly 30 to 40 percent of its mineral content before osteopenia is visible radiographically — so a normal-looking film never excludes osteoporosis. DEXA is required.[1]

Acute fracture is a surgical event, not a medical one

[1]

There is no resuscitation for osteoporosis itself — but an acute fragility fracture is a time-critical surgical and orthogeriatric event, and the medical team's job is to start bone therapy before discharge.[1][5]

Acute hip fracture is a surgical emergency under a combined orthogeriatric model: prompt work-up, surgical fixation or arthroplasty within 36 hours (the standard in national hip-fracture audits), early mobilisation, and prompt osteoporosis therapy. The single intervention that changes mortality is zoledronic acid 5 mg intravenously within 90 days of surgical repair, which cut further clinical fractures by 35 percent and all-cause mortality by 28 percent in the HORIZON recurrent-fracture trial — the evidence base for treating every hip-fracture patient before she leaves hospital. Acute painful vertebral fracture is managed with stepped analgesia (paracetamol, then a short opioid course; NSAIDs sparingly in the elderly), early mobilisation, brief external support, and vertebroplasty or kyphoplasty for persistent severe pain.[5]

The stepwise drug ladder — lifestyle, bisphosphonate, then the heavy artillery

Definitive management is a stepwise ladder: universal lifestyle and supplements for everyone, a first-line bisphosphonate for most, then denosumab or an anabolic for severe disease, then a drug-holiday review.[1][2]

Step 1 — the universal baseline. Prescribe weight-bearing, impact and resistance exercise (walking, jogging, dancing, weights) three to five times weekly; smoking cessation; limit alcohol to under 2 units a day; and a structured fall-prevention programme (home-hazard reduction, balance training, vision correction, medication review). Ensure calcium 1000 to 1200 mg a day (diet first, supplement the rest) and vitamin D 800 to 1000 IU a day, targeting a serum 25-hydroxy vitamin D of at least 50 to 75 nmol per litre. Calcium and vitamin D alone cut fractures in deficient, institutionalised elderly — but they are adjuncts, not substitutes, for specific therapy in established disease.[1][2]

Step 2 — first-line bisphosphonate. For osteoporosis, or osteopenia plus a FRAX over threshold, start a bisphosphonate: synthetic pyrophosphate analogues that bind hydroxyapatite and cripple osteoclast function and survival. Oral alendronate 70 mg once weekly (or risedronate 35 mg once weekly) is the workhorse; zoledronic acid 5 mg intravenously over at least 15 minutes once yearly is preferred when adherence or upper-gastrointestinal tolerability is the issue, in acute fracture, or for patients who prefer intermittent dosing. Ibandronate 150 mg orally once monthly (or 3 mg IV every 3 months) cuts vertebral but not robustly hip fracture. Counsel alendronate takers to take it fasting with water and stay upright 30 minutes.[3][4]

[3]

Step 3 — denosumab and the anabolics. Denosumab 60 mg subcutaneously every 6 months is as effective as a bisphosphonate, is not renally cleared (useful in CKD), and suits patients who prefer twice-yearly dosing — but it must never be stopped without a transition bisphosphonate, because withdrawal causes a rapid rebound in bone turnover and a cluster of multiple vertebral fractures within months. The anabolics — teriparatide (PTH 1-34) 20 micrograms subcutaneously daily and abaloparatide 80 micrograms daily — stimulate osteoblasts and build new bone; they are reserved for severe or very-high-risk disease (multiple fractures, very low T-score, or fracturing on therapy), with a 2-year lifetime limit.[6][7]

Step 4 — the older agents. Raloxifene 60 mg daily, a SERM, is a weaker antiresorptive that cuts vertebral (not hip) fractures and breast-cancer risk at the price of thromboembolism and hot flushes. Hormone replacement therapy prevents fractures but is now reserved for menopausal symptom control in younger postmenopausal women, at the lowest dose for the shortest time, because of breast-cancer, thromboembolic and cardiovascular risk. Calcitonin (salmon calcitonin 200 IU intranasal daily) is a weak antiresorptive now used mainly short-term for analgesia in acute painful vertebral fracture.[1]

Step 5 — the drug holiday. After 3 to 5 years of an oral bisphosphonate (or 3 years of IV zoledronate), reassess. In a stable, lower-risk patient with a T-score above minus 2.5 and no recent fractures, a 2 to 3 year holiday exploits the drug's prolonged skeletal retention while trimming the rare risks of atypical femoral fracture and osteonecrosis of the jaw. In a high-risk patient (T-score below minus 2.5, prior hip or spine fracture, or fracturing on therapy) treatment continues — up to 10 years has a favourable benefit-to-risk profile. The holiday is monitored with DEXA and turnover markers, and therapy resumes if risk rises, density falls, or a fracture occurs. A drug holiday applies only to bisphosphonates — never to denosumab.[1][2]

[2]

Glucocorticoids, men, and the build-then-lock patients

Glucocorticoid-induced osteoporosis (GIOP) is the commonest secondary osteoporosis and the most rapidly destructive — bone loss is fastest in the first 3 to 6 months, and fracture risk rises within weeks. Every patient expected to need prednisolone over 7.5 mg per day for over 3 months (often cited from 5 mg) should be assessed and given prophylactic bone protection: a bisphosphonate plus calcium and vitamin D, lifestyle measures, and the lowest effective steroid dose for the shortest time. FRAX can be used in GIOP but underestimates risk, so adjust it upward — roughly multiply the hip probability by 1.15 and the major-osteoporotic by 1.1, the equivalent of ageing the patient a decade.[1][2]

Male osteoporosis is under-recognised, and that under-recognition kills. About one in five men over 50 will fracture, and secondary causes turn up in roughly half to two-thirds of men with a fragility fracture — most often hypogonadism, steroid therapy (including for COPD and inflammatory disease), alcohol excess, smoking and hyperthyroidism. Always measure serum testosterone with LH and FSH in any man with low bone mass; testosterone replacement treats the hypogonadism and lifts BMD. Bisphosphonates and denosumab are first-line in men, teriparatide for severe disease.[1]

Post-fracture secondary prevention lives in the Fracture Liaison Service (FLS). Every patient over 50 presenting with a fragility fracture is identified, investigated (DEXA, secondary-cause screen) and started on therapy. FLS coverage is the single most effective — and most neglected — intervention to close the treatment gap, because the highest-risk patient on the planet is the one who has just fractured.[1][5]

Very-high-risk patients get anabolic first, then a lock. Patients with multiple or recent fractures, a T-score below minus 3.0 or minus 3.5, or a fracture sustained while on antiresorptive therapy are candidates for an anabolic agent first (teriparatide, abaloparatide or romosozumab), followed by a potent antiresorptive to lock in the gain. This build-then-lock sequence delivers larger BMD gains and fewer fractures than starting with an antiresorptive in this group — which is why romosozumab exists.[8][9]

Transplant and cancer-therapy bone loss is anticipatory. Patients about to start androgen-deprivation therapy for prostate cancer, aromatase-inhibitor therapy for breast cancer, or solid-organ or stem-cell transplantation face rapid, predictable bone loss within the first year. Measure a baseline DEXA, start calcium and vitamin D, and initiate a bisphosphonate (or denosumab) before or at the start of the gonadotropin-releasing-hormone agonist, aromatase inhibitor, or transplant immunosuppression — not after the bone is lost.[1]

The traps that harm patients — read this twice

Most preventable osteoporosis harm is a timing error — treating too late, stopping the wrong drug, or forgetting that a fracture already is the diagnosis.[1][2]

• Waiting for the T-score to cross minus 2.5 before treating a patient who has already fractured. A fragility fracture establishes the disease whatever the score; treating the next fracture, not the last, is the whole point.
• Stopping denosumab without a transition bisphosphonate. Withdrawal triggers a rapid rebound in turnover and a cluster of multiple vertebral fractures within months. Always bridge to a bisphosphonate.
• Forgetting prophylaxis on long-term glucocorticoids. Prednisolone over 7.5 mg for over 3 months earns a bisphosphonate plus calcium and vitamin D from day one — the bone loss is fastest in the first months.[1][2]
• Misreading the biochemistry. A raised calcium or ALP in a "fragility fracture" patient is not osteoporosis — it is hyperparathyroidism, myeloma, osteomalacia or Paget disease, and the treatment is entirely different.
• Leaving a hip-fracture patient on no bone therapy at discharge. A single zoledronate infusion within 90 days of repair cuts mortality by 28 percent; omitting it is a measurable, preventable death.[5]

[6]

Complications, prognosis — and the 28 percent that decides a hip-fracture service

The disease's complications are the fractures themselves; the drug's complications are the rare ones you must name. Effective therapy drops vertebral fracture by 40 to 70 percent, hip fracture by 25 to 50 percent, and nonvertebral fracture by 20 to 40 percent, and a single zoledronate infusion after a hip fracture cuts all-cause mortality by 28 percent. A prior fragility fracture roughly doubles future risk, highest in the "imminent risk" window immediately after the index fracture — the justification for prompt secondary prevention.[1][5]

Hip fracture carries a one-year mortality of 20 to 30 percent, a catastrophic loss of independence (half of previously independent patients need help with activities of daily living afterwards), and a high rate of immobility complications — venous thromboembolism, pressure ulcers, pneumonia, urinary infection. Vertebral fractures cause acute and chronic back pain, kyphosis with reduced vital capacity and restrictive physiology, early satiety and weight loss from the reduced abdominal cavity, and a raised future fracture and mortality risk proportional to severity.[1]

Drug complications are exactly what an examiner probes. Long-term bisphosphonates rarely cause atypical femoral fracture — a transverse, non-comminuted subtrochanteric or diaphyseal fracture, often preceded by weeks of prodromal thigh pain — and osteonecrosis of the jaw (exposed non-healing bone, usually after dental extraction in high-dose malignancy therapy). Both are rare in osteoporosis dosing but accumulate with duration, which is the rationale for the drug holiday. Acute-phase reaction (fever, myalgia, arthralgia) hits about 10 to 15 percent after the first IV zoledronate and is self-limiting; hypocalcaemia can follow zoledronate or denosumab, so replete vitamin D first.[1][2]

Pregnancy, the frail elderly, CKD, and the diabetic paradox

Pregnancy and lactation cause a transient, reversible loss of 3 to 10 percent of bone mass; bisphosphonates are contraindicated (teratogenic, long skeletal half-life), so management is calcium, vitamin D and lifestyle, with the rare pregnancy- and lactation-associated osteoporosis referred to a specialist.[1]

The elderly and frail are the highest-risk group and benefit most from fall-prevention programmes, vitamin D supplementation (which reduces falls in the deficient), home-hazard modification and IV zoledronate to overcome adherence problems — while avoiding sedating drugs and overtreatment that causes hypotension and falls.[1]

Chronic kidney disease changes the playbook: bisphosphonates are avoided below an eGFR of 30 to 35 mL per minute because of the risk of adynamic bone disease and accumulation, so denosumab (not renally cleared) becomes the preferred agent — with close attention to calcium, because denosumab-induced hypocalcaemia is worse in CKD.[1][2]

The diabetic paradox is worth a viva mark. Patients with type 2 diabetes have higher than average bone mineral density yet a paradoxically higher fracture risk, because chronic hyperglycaemia, advanced glycation end-products and altered collagen cross-linking wreck bone quality rather than quantity. DEXA and FRAX both underestimate skeletal fragility in diabetes, so use a lower threshold to treat and watch fall risk. The trabecular bone score (TBS), derivable from DEXA, helps capture the hidden risk.[1]

The trials that built the ladder

Modern osteoporosis therapy rests on a sequence of large placebo-controlled RCTs, each of which earned a drug its place on the ladder.[3][4][6][7]

[3] [4] [5] [6] [7] [8] [9]

US, UK, and the rest — where the thresholds diverge

Regional guideline differences are examinable and reflect different health-system economics. The FRAX algorithm itself was built on UK epidemiology.[10]

[2] [10] [1]

Monitoring, and prevention across a lifetime

Monitoring combines DEXA, turnover markers and an adherence check — and the commonest cause of treatment failure is that the patient never took the drug. Repeat DEXA every 1 to 2 years in high risk and up to 3 years in stable disease, and look for the least significant change — a change exceeding roughly 3 to 5 percent at the spine and 3 to 6 percent at the hip to be real. A stable or rising T-score confirms response; a falling T-score or rising turnover markers on therapy signal non-adherence (by far the commonest cause), an unrecognised secondary cause, or treatment failure, and should trigger review. Serum CTX should fall by at least one-third within 3 to 6 months of an oral bisphosphonate, or within days of IV zoledronate; a failure to fall means the drug was not taken or not absorbed.[2]

Prevention is staged across life. Build a high peak bone mass in youth (calcium, vitamin D, weight-bearing exercise; avoid smoking and excess alcohol); maintain bone through midlife; and detect and treat risk after the menopause and in older age. Population strategies — vitamin D and calcium sufficiency, physical activity, smoking and alcohol moderation, fall prevention, and Fracture Liaison Service coverage of every fragility-fracture patient — do more to reduce the fracture burden than any single drug.[1]

The mantra, and the mnemonics

[1] [2]

The mantra: A fragility fracture is osteoporosis whatever the score — bisphosphonate first, never stop denosumab without a transition.[1][6]

Ward-round test — three stems, thirty seconds each

Stem 1 — the missed warning fracture (answer)

A 72-year-old woman is admitted with an intertrochanteric hip fracture after a fall from standing height. She had a Colles fracture at 64 that was plastered and discharged; she takes no bone medication. Bloods: calcium 2.38, phosphate 1.1, ALP 95. Her DEXA femoral-neck T-score is minus 2.2. What is the diagnosis, and what must happen before she goes home? Model: She has established osteoporosis — the wrist fracture eight years ago already made the diagnosis regardless of the T-score, and the normal calcium, phosphate and ALP confirm it is osteoporosis, not osteomalacia, myeloma or hyperparathyroidism. Before discharge she must have surgical repair within 36 hours under an orthogeriatric model, a zoledronic acid 5 mg IV infusion within 90 days (cuts further fractures by 35% and mortality by 28%), a secondary-cause screen, calcium and vitamin D, and a bisphosphonate started — ideally via a Fracture Liaison Service. Waiting for the T-score to cross minus 2.5 is the preventable error that cost her this hip.[5]

Stem 2 — the glucocorticoid trap (answer)

A 58-year-old woman with rheumatoid arthritis has taken prednisolone 10 mg daily for 8 months. Her femoral-neck T-score is minus 1.8, she has never fractured, and her unadjusted FRAX 10-year hip-fracture probability is 1.8%. Does she warrant bone-protection therapy, and why? Model: Yes. Glucocorticoid use is itself a FRAX input, and the unadjusted FRAX underestimates her true risk — at prednisolone 7.5 mg per day or more the probability is adjusted upward (roughly multiplied by 1.15 for hip and 1.1 for major-osteoporotic fracture). On long-term steroids she meets the threshold for prophylactic bisphosphonate plus calcium and vitamin D regardless of the adjusted score, because bone loss is fastest in the first 3 to 6 months and she is already 8 months in. Teriparatide is preferred if her risk is very high. This is exactly the scenario in which waiting for the T-score to cross minus 2.5 — or for a fracture — is a preventable error.[1][2]

Stem 3 — the denosumab withdrawal trap (answer)

A 68-year-old woman has been on denosumab 60 mg subcutaneously six-monthly for 4 years with a stable T-score of minus 2.6. Her GP stops it because she is tired of injections and prescribes calcium and vitamin D alone. Four months later she presents with severe back pain and imaging shows three new vertebral fractures. What happened, and what was the correct plan? Model: This is the denosumab rebound — withdrawal causes a rapid rise in bone turnover and a cluster of multiple vertebral fractures within months of stopping, because denosumab's offset is fast and complete. Denosumab must never be stopped without a transition bisphosphonate: start a bisphosphonate (oral alendronate, or IV zoledronate if preferred) typically around 6 months after the last denosumab dose and continue for 12 to 24 months to cover the rebound window. A drug holiday applies only to bisphosphonates, never to denosumab. She now needs an anabolic agent (teriparatide or romosozumab) followed by a potent antiresorptive, because she is fracturing in the rebound window.[6]

References

1. [1]Compston JE, McClung MR, Leslie WD. Osteoporosis Lancet, 2019.PMID 30696576
2. [2]Camacho PM, Petak SM, Binkley N, et al. AMERICAN ASSOCIATION OF CLINICAL ENDOCRINOLOGISTS/AMERICAN COLLEGE OF ENDOCRINOLOGY CLINICAL PRACTICE GUIDELINES FOR THE DIAGNOSIS AND TREATMENT OF POSTMENOPAUSAL OSTEOPOROSIS-2020 UPDATE Endocr Pract, 2020.PMID 32427503
3. [3]Black DM, Cummings SR, Karpf DB, et al. Randomised trial of effect of alendronate on risk of fracture in women with existing vertebral fractures. Fracture Intervention Trial Research Group Lancet, 1996.PMID 8950879
4. [4]Black DM, Delmas PD, Eastell R, et al. Once-yearly zoledronic acid for treatment of postmenopausal osteoporosis N Engl J Med, 2007.PMID 17476007
5. [5]Lyles KW, Colón-Emeric CS, Magaziner JS, et al. Zoledronic acid and clinical fractures and mortality after hip fracture N Engl J Med, 2007.PMID 17878149
6. [6]Cummings SR, San Martin J, McClung MR, et al. Denosumab for prevention of fractures in postmenopausal women with osteoporosis N Engl J Med, 2009.PMID 19671655
7. [7]Neer RM, Arnaud CD, Zanchetta JR, et al. Effect of parathyroid hormone (1-34) on fractures and bone mineral density in postmenopausal women with osteoporosis N Engl J Med, 2001.PMID 11346808
8. [8]Cosman F, Crittenden DB, Adachi JD, et al. Romosozumab Treatment in Postmenopausal Women with Osteoporosis N Engl J Med, 2016.PMID 27641143
9. [9]Saag KG, Petersen J, Brandi ML, et al. Romosozumab or Alendronate for Fracture Prevention in Women with Osteoporosis N Engl J Med, 2017.PMID 28892457
10. [10]Kanis JA, Johnell O, Oden A, Johansson H, McCloskey E. FRAX and the assessment of fracture probability in men and women from the UK Osteoporos Int, 2008.PMID 18292978