Musculoskeletal

Osteoporosis-related fractures: secondary prevention

Clinical Overview and When to Suspect Recurrent Fragility Fracture

— A prior fragility fracture doubles to quintuples the risk of a subsequent fracture, with the highest risk in the first 1–2 years ("imminent fracture risk" window).

— Treatment gap is enormous: <25% of patients with hip or vertebral fractures are evaluated or treated for osteoporosis after discharge. Closing this gap is a recurrent Step 3 ambulatory and transitions-of-care theme.

— Hip fracture from low-energy mechanism at any T-score

— Vertebral compression fracture (clinical or morphometric) in adults ≥50

— Pelvis, proximal humerus, or distal forearm fracture from a fall from standing in a postmenopausal woman or man ≥50, with low bone mass on DXA or high FRAX

— Postmenopausal woman with wrist fracture after tripping; ED splints and discharges — what next?

— Older man post-hip ORIF being discharged to SNF; no bone health plan in chart

— Patient on chronic glucocorticoids (≥2.5 mg prednisone ≥3 months) with new back pain and height loss

Definition: Osteoporosis-related (fragility) fracture occurs from a fall from standing height or less, or with minimal trauma, in an adult ≥50. Once one fragility fracture has occurred, the patient enters a secondary prevention pathway — they are osteoporotic by clinical definition regardless of DXA T-score.

Why this matters on Step 3:

When to suspect/diagnose osteoporosis clinically (no DXA needed):

Typical Step 3 vignette triggers:

Step 3 management: Any fragility fracture is itself an indication to start pharmacotherapy — do not wait for DXA to initiate treatment in hip or vertebral fractures. Order DXA and labs in parallel, but treatment decision is already made.

Board pearl: A fragility fracture in a patient with a "normal" DXA still meets criteria for osteoporosis and for treatment. The fracture is the diagnosis.

Presentation Patterns and Key History

— Vertebral compression fracture: Acute mid/low thoracic or thoracolumbar back pain after bending, lifting, or coughing; ~2/3 are clinically silent and found incidentally on CXR or CT. Progressive kyphosis, height loss >4 cm from young-adult height, or early satiety from abdominal compression suggest cumulative vertebral disease.

— Hip fracture: Groin pain, inability to bear weight, shortened externally rotated leg after a fall to the side. In frail elderly, occasionally only knee or thigh pain.

— Distal radius (Colles): Fall on outstretched hand — often the sentinel fracture in the late 50s/early 60s, predicting hip fracture a decade later.

— Proximal humerus, pelvic ramus, rib: All count as fragility fractures with low-energy mechanism.

— Prior fractures (site, age, mechanism) — establishes very-high-risk status

— Glucocorticoid exposure (dose, duration), aromatase inhibitors, ADT for prostate cancer, PPIs, SSRIs, anticonvulsants, chronic heparin

— Nutrition: calcium intake, vitamin D, protein, alcohol >3 drinks/day, caffeine

— Tobacco, BMI <20, weight loss

— Falls in past year, near-falls, fear of falling, assistive device use

— Secondary causes: hyperthyroidism, hyperparathyroidism, celiac/IBD malabsorption, CKD, hypogonadism, multiple myeloma, RA, COPD

— Menopause age (<45 = early), amenorrhea history, family history of hip fracture

Index fracture presentations to recognize:

History elements that drive secondary prevention plan:

Key distinction: Osteoporotic vertebral fractures occur most often at T7–L2 (thoracolumbar junction). A compression fracture above T5 or with neurologic deficits should raise suspicion for malignancy or infection — that's not osteoporosis until proven otherwise.

Board pearl: Ask explicitly about height loss and falls at every postmenopausal visit — both are documented quality measures and high-yield USMLE prompts for ordering DXA or initiating therapy.

Physical Exam Findings and Functional/Fall Assessment

— Measured height at every visit; loss ≥2 cm prospectively or ≥4 cm from peak height → image the spine

— Thoracic kyphosis ("dowager's hump"); rib-to-pelvis distance <2 fingerbreadths suggests multiple vertebral compressions

— Wall–occiput distance >5 cm (patient stands against wall, can't touch occiput) — sensitive for occult vertebral fracture

— Point tenderness over spinous processes in acute VCF

— Timed Up and Go (TUG): ≥12 seconds = elevated fall risk

— 30-second chair stand and 4-stage balance test

— Gait observation: shuffling, antalgic, wide-based

— Orthostatic vitals — especially before starting/continuing antihypertensives, alpha blockers, sedatives

— Visual acuity, footwear inspection, cognitive screen (MMSE/MoCA if indicated)

— Benzodiazepines, zolpidem, anticholinergics, opioids, tricyclics, antipsychotics, sliding-scale insulin, alpha blockers — each independently raises fall risk

— STOPP/Beers criteria flag many of these

Targeted skeletal exam:

Functional and fall-risk assessment (cornerstone of secondary prevention):

Medication review at bedside ("deprescribing exam"):

Home hazards assessment (ask or refer OT): throw rugs, lighting, bathroom grab bars, stair railings, pets, cords.

Step 3 management: A patient discharged after a hip fracture should leave with: (1) bone-active drug ordered or scheduled, (2) PT/OT referral, (3) home safety assessment, (4) medication reconciliation removing at least one fall-promoting agent when feasible, and (5) vitamin D + calcium plan.

Board pearl: Fall prevention reduces fracture risk independently of antiresorptive therapy — Step 3 vignettes that omit fall mitigation are usually wrong answers. Vitamin D supplementation and structured exercise (balance + resistance) reduce falls in community-dwelling elders.

Diagnostic Workup — Imaging, DXA, and Initial Labs

— Plain radiographs of the symptomatic site; if hip fracture suspected with negative XR, obtain MRI hip (sensitive for occult femoral neck fracture) — CT is second-line.

— Vertebral imaging: Lateral thoracic/lumbar XR, or VFA (vertebral fracture assessment) during DXA. Indicated in women ≥70, men ≥80, height loss >4 cm, recent low-trauma fracture, or chronic glucocorticoids.

— Genant semiquantitative grading (I 20–25%, II 25–40%, III >40% height loss).

— Order even after fracture for baseline and to guide treatment intensity/duration. Do not delay therapy waiting for DXA in clear fragility fracture.

— Report includes T-score (postmenopausal women, men ≥50) and Z-score (premenopausal, <50, children). T ≤ −2.5 = osteoporosis; Z ≤ −2.0 = "below expected for age" → workup secondary causes.

— TBS (trabecular bone score) if available — refines FRAX in diabetes and glucocorticoid use.

— CBC, CMP (Ca, Cr, alk phos, albumin, LFTs), 25-OH vitamin D, TSH, PTH, 24-hour urine calcium and creatinine, SPEP/UPEP and free light chains in older adults or anemia, testosterone in men, celiac serology (tTG-IgA) if GI symptoms, AM cortisol if Cushingoid features.

— Phosphorus and alk phos help screen for osteomalacia.

Confirm the index fracture:

DXA (central, hip + lumbar spine):

FRAX 10-year risk (not strictly needed if fracture already present, but used to stratify "very high risk").

Initial labs — secondary cause screen (mandatory before long-term therapy):

Key distinction: Osteoporosis = low bone mass + normal mineralization (normal Ca, P, alk phos). Osteomalacia = defective mineralization, often with low vit D, low Ca/P, elevated alk phos, and pseudofractures (Looser zones). Treating osteomalacia with a bisphosphonate without replacing vitamin D worsens hypocalcemia.

Board pearl: Always check and correct 25-OH vitamin D (goal ≥30 ng/mL) and serum calcium before starting any antiresorptive — failure causes symptomatic hypocalcemia, especially with IV zoledronate or denosumab.

Diagnostic Workup — Advanced and Confirmatory Studies

— CTX (C-telopeptide, resorption) and P1NP (procollagen type 1 N-propeptide, formation).

— Use case: baseline before therapy, then repeat at 3–6 months to assess adherence/response — a >25% decrease in CTX on antiresorptives suggests good response.

— Not required for diagnosis; high-yield for monitoring and adherence questions on Step 3.

— MRI spine when vertebral fracture is above T5, multiple levels, neurologic deficit, weight loss, fever, immunosuppression, or known malignancy — to rule out pathologic fracture, infection, or cord compromise.

— Bone scan or PET if multifocal pain and concern for metastasis.

— Multiple myeloma: SPEP, UPEP, serum free light chains, skeletal survey or whole-body low-dose CT

— Primary hyperparathyroidism: ↑Ca, ↑PTH, ↑24-hr urine Ca; confirm with sestamibi if surgical

— Hypercortisolism: late-night salivary cortisol or low-dose dexamethasone suppression

— Hypogonadism (men): AM total testosterone × 2; LH/FSH if low

— Hyperthyroidism / suppressive levothyroxine: TSH

— Mastocytosis: serum tryptase if flushing/GI symptoms

— Celiac disease: tTG-IgA + total IgA

— CKD-MBD: PTH, phosphate, 1,25-OH vit D — bisphosphonates avoided if eGFR <30–35

Bone turnover markers (BTMs):

Advanced imaging for atypical or red-flag features:

Workup for secondary osteoporosis (expanded panel when Z ≤ −2.0, recurrent fractures despite therapy, or atypical features):

Hip geometry / atypical femoral fracture surveillance: in patients on long-term bisphosphonate or denosumab with new thigh/groin pain, obtain bilateral femur radiographs; if equivocal, MRI or bone scan to detect prodromal stress reaction.

CCS pearl: When a CCS case presents post-fracture, order DXA, 25-OH vit D, CMP, TSH, PTH, SPEP (if older), and testosterone (if male) as a clustered batch on day 1 — then advance the clock and start therapy once labs return normal/treatable.

Board pearl: A new fragility fracture while on therapy mandates re-evaluation for secondary causes and adherence before declaring treatment failure.

Risk Stratification and Management Decision Tree

— Fracture within the past 12 months (imminent risk)

— Multiple fractures

— Fractures while on osteoporosis therapy

— T-score ≤ −3.0

— Very high FRAX (10-yr hip ≥4.5% or major osteoporotic ≥30%)

— High fall risk

— Fractures on chronic glucocorticoids

— High risk (single fracture, T ≤ −2.5, FRAX above threshold): start oral bisphosphonate (alendronate or risedronate) as first-line; IV zoledronate if intolerant, nonadherent, or post-hip fracture.

— Very high risk: start with an anabolic (teriparatide, abaloparatide, or romosozumab) for 1–2 years, followed by an antiresorptive to lock in gains. Going anabolic→antiresorptive is correct; antiresorptive→anabolic blunts anabolic response.

— IV zoledronate 5 mg is preferred — initiate ≥2 weeks after the fracture/surgery (allows for early callus formation and vitamin D repletion).

— Trial data (HORIZON-RFT): annual zoledronate after hip fracture reduced new clinical fractures and all-cause mortality.

All post-fragility-fracture patients are at least "high risk." Identify the "very high risk" subset — they merit anabolic-first therapy:

Decision logic (AACE/Endocrine Society 2020 framework, widely tested):

Post-hip fracture pathway (very high-yield):

Glucocorticoid-induced osteoporosis (GIOP): Any adult starting ≥7.5 mg/day prednisone for ≥3 months, or with prior fragility fracture on any steroid dose, should receive pharmacotherapy. Oral bisphosphonate first-line; teriparatide preferred if very high risk.

Step 3 management: Build the discharge order set: (1) calcium 1,000–1,200 mg/day total (diet + supplement), (2) vitamin D 800–2,000 IU/day to keep 25-OH ≥30, (3) bone-active agent chosen by risk tier, (4) PT for balance/resistance training, (5) DXA scheduled, (6) follow-up in 4–6 weeks.

Board pearl: "Drug holiday" is never appropriate immediately after a fragility fracture, regardless of prior treatment duration — restart or escalate therapy.

Pharmacotherapy — First-Line and Sequential Regimens

— Alendronate 70 mg PO weekly or risedronate 35 mg PO weekly / 150 mg monthly: first-line in high-risk patients. Take on empty stomach with 8 oz water, remain upright 30–60 min, no food/meds for 30 min. Contraindicated if eGFR <30–35, esophageal stricture/achalasia, inability to remain upright, or uncorrected hypocalcemia.

— Ibandronate: reduces vertebral fractures only — not preferred after hip fracture.

— IV zoledronate 5 mg yearly: preferred post-hip fracture, in nonadherent patients, or GI intolerance. Pretreat with acetaminophen; warn about acute-phase reaction (flu-like sx 24–72 h, ~30% first dose). Hold if eGFR <35.

— Denosumab 60 mg SC q6 months: RANKL inhibitor; useful in CKD (no dose adjustment, but monitor calcium closely if eGFR <30 — risk of severe hypocalcemia). Cannot be discontinued without bridging — stopping causes rapid bone loss and rebound multiple vertebral fractures within 6–18 months. Always follow with a bisphosphonate.

— Teriparatide (PTH 1-34) 20 mcg SC daily × up to 2 years lifetime. Contraindicated with prior radiation, Paget disease, hypercalcemia, bone metastases.

— Abaloparatide (PTHrP analog) 80 mcg SC daily × up to 2 years.

— Romosozumab (sclerostin Ab) 210 mg SC monthly × 12 months: dual anabolic + antiresorptive effect. Black box: increased MI/stroke — avoid if cardiovascular event within 1 year.

— Calcium 1,000–1,200 mg/day (diet preferred), vitamin D 800–2,000 IU/day, target 25-OH ≥30 ng/mL.

— Estrogen/raloxifene: limited role; raloxifene reduces vertebral fractures + invasive breast cancer risk; raises VTE risk.

Antiresorptives:

Anabolics (very high risk / treatment failure):

Sequential strategy: Anabolic → antiresorptive. After teriparatide/abaloparatide/romosozumab, transition immediately to alendronate, zoledronate, or denosumab to preserve BMD gains.

Adjuncts:

Board pearl: Selecting zoledronate or denosumab over oral bisphosphonate is correct in patients with swallowing disorders, GERD, polypharmacy, dementia, or post-hip-fracture rehab placement — adherence to oral bisphosphonate at 1 year is <50%.

Procedures and Expanded Pharmacology Considerations

— Reserved for severe, refractory pain after 4–6 weeks of conservative therapy (analgesia, bracing, early mobilization), or progressive neurologic compromise.

— Evidence is mixed; recent guidelines (ACR, NICE) favor selective use. Does not alter osteoporosis trajectory — patients still need pharmacotherapy.

— Femoral neck (displaced): hemiarthroplasty or total hip arthroplasty

— Femoral neck (nondisplaced) or intertrochanteric: internal fixation (cephalomedullary nail or DHS)

— Goal: surgery within 24–48 hours reduces mortality and complications. Multidisciplinary geriatric–ortho co-management reduces delirium, length of stay, and 1-year mortality.

— IV zoledronate ideally given ≥2 weeks after fracture/surgery and after vit D repletion (25-OH ≥20–30 ng/mL) and normocalcemia.

— Denosumab and teriparatide can be initiated during acute hospitalization once labs are acceptable.

— Subtrochanteric/diaphyseal transverse fracture with cortical beaking, often bilateral, after years of bisphosphonate/denosumab.

— Stop the bisphosphonate, initiate teriparatide (promotes healing), prophylactic intramedullary nailing of contralateral femur if prodromal lesion.

— Rare with osteoporosis dosing (<1/10,000 patient-yr); much higher with oncologic IV bisphosphonate/denosumab dosing.

— Pre-treatment dental evaluation recommended; complete invasive dental work before initiating therapy if feasible. Routine cleanings are fine.

Vertebroplasty / kyphoplasty for VCF:

Hip fracture operative management (orthopedics):

Initiating pharmacotherapy peri-fracture:

Atypical femur fracture (AFF) management:

Osteonecrosis of the jaw (ONJ):

CCS pearl: In a CCS hip fracture case, on day 1 order: type & screen, CBC, BMP, ECG, CXR, troponin if symptoms, DVT prophylaxis, IV fluids, regional/multimodal analgesia, ortho consult, geriatric medicine consult. On day of/after surgery, order vit D, calcium, DXA outpatient, schedule zoledronate at 2-week post-op visit, and refer to PT.

Board pearl: Bisphosphonates improve fracture healing in animal models and do not delay union clinically — do not withhold therapy for fear of nonunion.

Special Populations — Elderly and Renal/Hepatic Impairment

— Highest absolute fracture risk → highest absolute benefit from therapy. Do not withhold based on age alone; consider life expectancy (>~1 year of expected benefit before drug acts).

— Prefer IV zoledronate or denosumab for adherence; oral bisphosphonates often fail due to polypharmacy, swallowing, GERD, and cognitive impairment.

— Aggressive fall mitigation, vision correction, deprescribing of sedatives and anticholinergics.

— Bisphosphonates: contraindicated if eGFR <30–35 mL/min. Renal toxicity reported with rapid IV infusion — give zoledronate over ≥15 minutes with hydration.

— Denosumab: not renally cleared, can be used in advanced CKD, but risk of severe symptomatic hypocalcemia rises sharply at eGFR <30 and in dialysis patients — monitor Ca, Mg, P, and PTH; ensure adequate vit D before dosing.

— CKD-MBD workup before treating: PTH, phosphate, alk phos, 25-OH vit D, and bone-specific evaluation. Adynamic bone disease can mimic osteoporosis but is worsened by antiresorptives — bone biopsy may be needed in advanced CKD before initiating therapy.

— Teriparatide is acceptable in CKD but watch for hypercalcemia.

— Romosozumab — limited renal data; cardiovascular caution dominates.

— Simplify regimens; once-yearly zoledronate is often ideal.

— Reassess goals of care; in a patient with life expectancy <1 year, focus shifts to fall prevention, pain control, vitamin D, and avoiding new fractures rather than initiating expensive long-term agents.

Very elderly (≥80):

Chronic kidney disease:

Hepatic impairment: No significant dose adjustments for bisphosphonates, denosumab, or teriparatide; monitor calcium and vit D, as malabsorption from cholestasis lowers vit D.

Frailty and cognitive impairment:

Step 3 management: For a nursing-home resident post-hip fracture with eGFR 28, denosumab + careful Ca/vit D repletion is typically the correct answer rather than zoledronate. If denosumab is started, plan the next dose at 6 months without fail — missed doses cause rebound fractures.

Board pearl: Never start denosumab unless you have a plan for indefinite continuation or a bisphosphonate bridge at discontinuation.

Special Populations — Premenopausal Women, Men, and GIOP

— Account for ~30% of hip fractures; under-treated. After a fragility fracture, work up hypogonadism (AM testosterone), alcohol use, COPD/steroid exposure, hyperparathyroidism, hemochromatosis, and myeloma.

— Treatment thresholds and agents mirror women: alendronate, risedronate, zoledronate, denosumab, teriparatide all approved for male osteoporosis.

— Testosterone replacement alone is not osteoporosis therapy — treat the osteoporosis separately.

— Always pathological until proven otherwise. Evaluate for amenorrhea/Female Athlete Triad/RED-S, eating disorders, celiac, IBD, hyperthyroidism, hyperparathyroidism, Cushing, mastocytosis, idiopathic juvenile osteoporosis.

— Address underlying cause first; pharmacotherapy reserved for ongoing fractures or severe BMD loss. Bisphosphonates have long skeletal half-life → caution in women considering pregnancy (potential fetal exposure).

— Teriparatide is option in glucocorticoid-induced cases.

— Rare; presents as VCFs in late pregnancy or postpartum. Stop breastfeeding, ensure Ca/vit D; teriparatide or denosumab considered case-by-case.

— Bone loss begins within 3 months; greatest in first year.

— ACR 2017/2022: Any adult ≥40 on prednisone ≥2.5 mg/day for ≥3 months, plus moderate-to-high fracture risk, warrants pharmacotherapy. For adults ≥40 with prior fragility fracture on any steroid dose, treat.

— First-line: oral bisphosphonate. Teriparatide preferred for very-high-risk GIOP.

— Treatment-induced bone loss; baseline DXA, then antiresorptive (denosumab 60 mg SC q6mo, zoledronate, or alendronate) per oncologic guidelines.

Men:

Premenopausal women with fragility fracture:

Pregnancy- and lactation-associated osteoporosis:

Glucocorticoid-induced osteoporosis (GIOP):

Aromatase inhibitor (breast cancer) and ADT (prostate cancer):

Key distinction: Pre-menopausal women use Z-scores, not T-scores, and the diagnostic label is "low bone mass for age" rather than osteoporosis unless a fragility fracture has occurred.

Board pearl: A young woman with low BMD and amenorrhea — restore menses and nutrition first; bisphosphonates are rarely the answer on Step 3.

Complications and Adverse Outcomes

— Hip fracture: 20–30% 1-year mortality, with excess deaths from PE, pneumonia, MI, infections. ~50% never regain prior functional status; ~25% need long-term institutionalization.

— Vertebral fractures: chronic pain, kyphosis, restrictive lung disease, GERD/early satiety, depression, increased risk of further VCFs ("vertebral cascade").

— Distal radius: chronic regional pain syndrome, decreased grip, predictor of future hip fracture.

— Pelvic fragility fractures: pain, immobility, DVT/PE, decubitus ulcers.

— Oral bisphosphonates: esophagitis, dyspepsia, esophageal ulcer/stricture (mitigated by upright dosing).

— IV zoledronate: acute-phase reaction (flu-like, ~30% on first dose), hypocalcemia, renal injury if dehydrated or eGFR <35, ocular inflammation (rare).

— Denosumab: hypocalcemia (especially CKD), cellulitis, eczema, rebound vertebral fractures if discontinued without bridge.

— Atypical femoral fractures (AFF): rare (~1/10,000 patient-years) after long-term antiresorptive; subtrochanteric/diaphyseal transverse fracture, often bilateral, preceded by thigh/groin pain. Stop drug, consider teriparatide, prophylactic nailing if prodromal.

— Osteonecrosis of the jaw (ONJ): rare at osteoporosis doses; risk factors include dental extractions, poor oral hygiene, diabetes, smoking, concurrent steroids/chemo.

— Romosozumab: MI, stroke, cardiovascular death (black box); avoid if MI/CVA within 12 months.

— Teriparatide/abaloparatide: hypercalcemia, orthostasis on first dose, nausea, leg cramps; theoretical osteosarcoma risk (animal data) — historical black box now revised.

Of the fracture itself:

Of immobility/hospitalization: delirium, hospital-acquired pneumonia, UTI, pressure injury, VTE, deconditioning.

Pharmacotherapy adverse effects:

Step 3 management: New thigh pain in a patient on >3–5 years of bisphosphonate → bilateral femur XR ± MRI, stop drug, ortho referral, switch to anabolic. Don't dismiss as overuse.

Board pearl: The absolute benefit of antiresorptives (preventing dozens of clinical fractures per 1,000 patient-years in high risk) vastly exceeds the rare AFF and ONJ risks — counsel quantitatively.

When to Escalate Care — Consults, Inpatient Triage, and Co-management

— All hip fractures: admit for surgical optimization; target OR within 24–48 hours.

— Pelvic fragility fractures with inability to ambulate, intractable pain, or hemodynamic concern (sacral/pubic ramus bleeding in elderly on anticoagulation).

— Vertebral fracture with neurologic deficit, cord compression, cauda equina, or T-spine fractures above T5 — neurosurgery consult.

— Suspected pathologic fracture (myeloma, metastasis) — admit for workup if symptomatic.

— Inability to manage at home: uncontrolled pain, fall risk without supervision, dehydration.

— Orthopedic surgery: all hip fractures, displaced fractures, surgical VCF candidates.

— Geriatric medicine / hospitalist co-management: reduces delirium, mortality post-hip fracture — Step 3 favored answer.

— Endocrinology: recurrent fractures on therapy, complex secondary causes (severe hyperparathyroidism, Cushing, mastocytosis), very high risk requiring anabolic sequencing, severe CKD-MBD.

— PM&R / PT-OT: every patient before discharge.

— Pain management / palliative care: refractory VCF pain, multimodal regimens.

— Dental: before initiating long-term antiresorptive when major work pending.

— Nutrition / dietitian: calcium, protein, vit D optimization.

Inpatient admission criteria (post-fragility-fracture ED visit):

Consultations to consider:

Fracture Liaison Service (FLS): A coordinated, nurse- or NP-led model that identifies post-fracture patients, ensures DXA, initiates therapy, and arranges follow-up. Reduces refracture and mortality; high-yield as a systems-based answer on Step 3.

CCS pearl: For a hip-fracture CCS case, order ortho consult, geriatric medicine co-management, PT/OT, DVT prophylaxis, multimodal pain control (avoid meperidine, minimize opioids), DXA outpatient, vitamin D level, and schedule zoledronate at 2 weeks post-op. Counseling actions ("counsel about home safety," "counsel about smoking cessation") are critical for the score.

Board pearl: Hip-fracture mortality reduction is achieved by early surgery + co-management + post-discharge antiresorptive — all three. Missing any one is the wrong-answer pattern.

Key Differentials — Other Causes of Low Bone Mass (Same Category)

— Defective mineralization. Diffuse bone pain, proximal muscle weakness, waddling gait. Labs: low 25-OH vit D, low Ca, low phosphate, elevated alk phos, secondary hyperparathyroidism. Imaging: Looser zones (pseudofractures) on pubic rami, scapulae, femoral necks. Treatment: high-dose vit D ± phosphate, treat malabsorption.

— Hypercalcemia, elevated PTH, low phosphate, hypercalciuria. Preferentially affects cortical bone → distal radius BMD disproportionately low. Subperiosteal resorption on hand XR. Parathyroidectomy curative.

— Older patient with anemia, renal injury, hypercalcemia, bone pain, pathologic fractures. Punched-out lytic lesions on skeletal survey; SPEP/UPEP/free light chains; bone marrow biopsy. Bisphosphonates/denosumab used adjunctively, but the disease is the target.

— Pathologic fractures, often above T5 or in pedicles; mixed lytic/blastic lesions on MRI/CT. Always consider when fracture pattern, age, or oncologic history doesn't fit osteoporosis.

— Bone pain, deformity (bowed tibia), hearing loss, isolated elevated alkaline phosphatase with normal Ca/P, mosaic pattern on biopsy. Lytic and blastic phases on XR. Treat with bisphosphonates (zoledronate single infusion often curative).

— Family history, blue sclerae, dentinogenesis imperfecta, hearing loss, multiple fractures from childhood. Genetic testing.

— Mix of high- and low-turnover bone disease; PTH, phosphate, vit D, FGF-23 deranged. Bone biopsy distinguishes adynamic bone disease — bisphosphonates can worsen it.

Osteomalacia / vitamin D deficiency:

Primary hyperparathyroidism:

Multiple myeloma:

Bone metastases (breast, prostate, lung, kidney, thyroid):

Paget disease:

Osteogenesis imperfecta (adult-detected mild forms, type I):

Renal osteodystrophy / CKD-MBD:

Key distinction: Normal Ca, P, alk phos with fragility fracture → osteoporosis. Abnormal alk phos or calcium → look elsewhere first.

Board pearl: Any vertebral fracture above T5, multiple lytic lesions, B-symptoms, anemia, hypercalcemia, or elevated alk phos in isolation = not osteoporosis until proven — order SPEP/UPEP, skeletal survey, MRI as indicated.

Key Differentials — Other-Category Mimics and Comorbid Conditions

— Acute onset, point tenderness, height loss, focal kyphosis suggest VCF. Chronic non-specific axial pain without neurologic findings and normal XR is usually degenerative. Order imaging when red flags present.

— Fever, IVDU, immunosuppression, recent bacteremia, focal severe pain, elevated CRP/ESR. MRI with contrast is the diagnostic test. Missed diagnoses cause permanent neurologic injury — Step 3 patient-safety vignette territory.

— Neurogenic claudication, dermatomal pain, positive straight-leg raise. Imaging guides; not a fracture.

— Tearing chest/back pain, asymmetric pulses, hypertension. CT angiogram. Important not to miss in older adults with "new back pain."

— Can present as flank/back pain plus hypotension after a fall, mimicking pelvic fragility fracture.

— Syncope from arrhythmia, aortic stenosis, postural hypotension, hypoglycemia, seizure. Always evaluate why the patient fell — order ECG, orthostatic vitals, glucose, BMP, CBC, urinalysis, and consider echo or telemetry in unexplained falls.

— A "mechanical fall" diagnosis without workup is a Step 3 pitfall.

— Bilateral shoulder/hip girdle pain and stiffness, elevated ESR/CRP. Easily mistaken for fragility fracture pain in elderly.

— Joint-localized findings; aspirate if effusion.

Mechanical/degenerative back pain vs vertebral compression fracture:

Spinal infection (vertebral osteomyelitis, discitis, epidural abscess):

Spinal stenosis, radiculopathy, herniated disc:

Aortic dissection or AAA referred pain:

Retroperitoneal hematoma in anticoagulated elderly:

Falls — non-musculoskeletal etiologies that look like fragility fracture:

Polymyalgia rheumatica / inflammatory myopathy:

Osteoarthritis flare, septic joint, gout:

Step 3 management: For an older adult with a "mechanical fall" and fragility fracture, workup the fall (cardiac, neuro, metabolic) AND treat the bone disease AND mitigate fall risk. Doing only one is incomplete and scores poorly.

Board pearl: Don't anchor on "osteoporotic fracture" — confirm the mechanism makes sense, the fracture location is typical (T7–L2, hip, wrist), and the systemic workup is clean before committing to lifelong pharmacotherapy.

Secondary Prevention / Discharge Plan / Long-Term Strategy

— Bone-active agent initiated or scheduled (zoledronate at 2 weeks, oral bisphosphonate at discharge, denosumab in CKD, anabolic if very high risk)

— Calcium 1,000–1,200 mg/day total (food first)

— Vitamin D3 800–2,000 IU/day, target 25-OH ≥30 ng/mL

— Adequate protein ~1.0–1.2 g/kg/day in older adults

— Pain regimen: acetaminophen scheduled, topical agents, judicious short-course opioids — minimize benzodiazepines and muscle relaxants in elderly

— VTE prophylaxis per surgical guideline (hip fracture: LMWH or DOAC for 28–35 days post-op)

— Deprescribe: review and stop at least one fall-promoting drug when feasible

— Smoking cessation, alcohol ≤1–2 drinks/day max

— Weight-bearing aerobic + resistance + balance exercise (e.g., supervised PT, tai chi) ≥3×/week

— Adequate sunlight or supplementation

— Home safety modifications: grab bars, raised toilet seat, night-lights, remove throw rugs, footwear

— Alendronate: reassess at 5 years. If still high risk → continue to 10 years. If risk has dropped (T > −2.5, no new fracture) → consider 1–2 year holiday with monitoring.

— Zoledronate: reassess at 3 years. Continue to 6 years if high risk.

— Denosumab: do not holiday — transition to bisphosphonate when stopping.

— Anabolics: cap at 2 years (teriparatide/abaloparatide) or 1 year (romosozumab), then antiresorptive.

Discharge medication bundle after every fragility fracture:

Lifestyle counseling:

Duration of therapy and drug holidays:

Vaccinations (often overlooked Step 3 detail): pneumococcal, influenza, RSV, zoster, COVID-19 — pneumonia is a leading cause of post-hip-fracture mortality.

Fracture Liaison Service or care coordinator enrollment.

Step 3 management: Communicate the plan to PCP via structured handoff; many refractures occur from dropped post-discharge follow-up. The transition from inpatient ortho team → SNF → PCP is the highest-risk window.

Board pearl: No drug holiday after a recent fragility fracture. The fracture itself resets the clock.

Follow-Up, Monitoring Parameters, and Rehabilitation

— 2–4 weeks post-discharge: pain control, wound, fall prevention, confirm pharmacotherapy started, vitamin D level back, calcium normal

— 3–6 months: medication adherence, side effects, repeat 25-OH vit D and CMP, bone turnover marker if used (CTX or P1NP)

— 1–2 years: repeat DXA (lumbar spine and hip, same machine). Stable or improved BMD = treatment success; loss >5% in spine or >4% in hip suggests adherence issue or treatment failure.

— Annual: height, fall history, medication review, vit D, calcium

— New fragility fracture after 12 months of adherent therapy

— Significant BMD loss exceeding least significant change

— Persistent elevation in CTX/P1NP despite antiresorptive therapy

→ Reassess adherence and absorption first; rescreen for secondary causes; switch to a different class, often to anabolic.

— Day 0–1 post-op mobilization (weight-bearing as tolerated when fixation allows) reduces mortality.

— Inpatient → skilled nursing or home PT. Goal: prior ambulatory baseline by 3–6 months.

— Programs combining balance + progressive resistance training (e.g., Otago) reduce falls 30–40%.

— Adherence: oral bisphosphonate adherence at 1 year <50% — set expectations, consider IV if oral fails.

— Realistic timelines: bone-active drugs reduce vertebral fractures within ~6–12 months and hip fractures within 12–24 months — patients abandoning at 3 months because "no change" is a key adherence pitfall.

— Calcium from food first; supplements may slightly raise CV risk if excessive.

Follow-up cadence:

Defining treatment failure:

Rehabilitation post-hip fracture:

Counseling priorities:

Quality measures (Step 3 systems thinking): Post-fracture osteoporosis assessment and treatment within 6 months is a CMS/HEDIS measure — relevant to value-based payment and Step 3 health-systems items.

CCS pearl: Schedule "Office visit, 4 weeks" and "Office visit, 6 months" after starting therapy. Order "DXA, central, in 1 year" and "25-OH vitamin D, in 3 months" — CCS rewards specific monitoring orders, not vague follow-ups.

Board pearl: Persistent VCF pain >6 weeks despite analgesia and bracing = re-image (rule out new level/malignancy) and consider kyphoplasty referral.

Ethical, Legal, and Patient Safety Considerations

— Many post-hip-fracture patients have delirium or cognitive impairment. Use decision-making capacity assessment (understanding, appreciation, reasoning, expression of choice). For surgery and anesthesia, obtain consent from a legally authorized surrogate if capacity is lacking. Document carefully — board questions test recognition that "next of kin" hierarchy varies by state.

— Anabolic therapies (romosozumab cardiovascular risk; teriparatide historical osteosarcoma boxed concerns) merit explicit risk discussion and documentation.

— In patients with limited life expectancy (<1–2 years), discuss whether starting a new bisphosphonate is consistent with goals. Calcium, vitamin D, fall prevention, and pain control remain appropriate at all life stages.

— Hospital → SNF → home → PCP handoff often loses the bone-health plan. Explicitly hand off: pharmacotherapy initiated, next dose due date (especially denosumab q6 months), DXA scheduled, follow-up appointments, deprescribed agents and rationale.

— Missed denosumab dose >7 months → significant rebound vertebral fracture risk — flagged as a medication safety event.

— Beers criteria, STOPP/START — deprescribing benzodiazepines, anticholinergics, sliding-scale insulin, and unnecessary antihypertensives is a measurable safety intervention.

— Suspected elder abuse or neglect in a fall/fracture presentation (delayed presentation, inconsistent history, multiple healing fractures, caregiver controlling history, pressure injuries) → mandatory reporting to Adult Protective Services in all US states. Safety of the patient takes precedence over confidentiality.

— DXA, anabolic agents, and FLS programs are unevenly available — Step 3 may test recognition of disparities (rural, racial, insurance barriers) and use of patient-assistance and care-coordination resources.

Informed consent and capacity:

Goals of care and shared decision-making:

Transitions of care — highest-risk window for medical error:

Polypharmacy and fall-related harm:

Mandatory reporting:

Driving safety: After hip surgery or significant fracture, counsel on driving restrictions until cleared.

Equity and access:

Step 3 management: When a patient declines treatment, document capacity, the risks discussed (especially the high 1-year refracture and mortality risk after hip fracture), alternatives offered, and a plan to revisit at follow-up — respect autonomy but don't simply drop the issue.

Board pearl: Suspected elder abuse → report and ensure a safe disposition before discharge, even if it means social work hold or hospital admission.

High-Yield Associations and Rapid-Fire Clinical Facts

Fragility fracture = osteoporosis, regardless of DXA T-score. Treat.

Hip fracture carries 20–30% 1-year mortality; geriatric–ortho co-management reduces it.

Imminent risk window: highest refracture rate is in the first 12–24 months after a fracture.

Vertebral cascade: one VCF → 5× risk of another within 1 year.

DXA thresholds (postmenopausal women, men ≥50): T ≤ −2.5 = osteoporosis; −1.0 to −2.5 = osteopenia/low bone mass.

USPSTF screening (primary prevention context): DXA in women ≥65, and in younger postmenopausal women at increased FRAX risk; insufficient evidence for men — but secondary prevention after fracture is universally indicated.

Calcium 1,000–1,200 mg/day; vitamin D 800–2,000 IU/day, goal 25-OH ≥30 ng/mL.

First-line antiresorptive: alendronate or risedronate; post-hip fracture: IV zoledronate.

Denosumab cannot be stopped without bisphosphonate bridge — rebound vertebral fractures.

Anabolic-first in very high risk: teriparatide, abaloparatide, romosozumab → followed by antiresorptive.

Romosozumab black box: CV events — avoid within 12 months of MI/stroke.

AFF: subtrochanteric/diaphyseal transverse fracture after long-term antiresorptive → stop drug, teriparatide.

ONJ: rare at osteoporosis doses; complete invasive dental work before therapy if possible.

Bisphosphonate contraindicated if eGFR <30–35, esophageal disorders, uncorrected hypocalcemia.

Zoledronate: pretreat with acetaminophen and IV fluids; first-dose acute-phase reaction common.

Glucocorticoid threshold for GIOP therapy: ≥2.5–7.5 mg prednisone/day for ≥3 months in adults ≥40 with risk.

Drug holiday: alendronate at 5 yrs, zoledronate at 3 yrs — only if low risk and no new fracture.

Bone turnover markers: CTX (resorption), P1NP (formation) — monitoring tools, not diagnostic.

Fall prevention: vitamin D + balance/resistance exercise + medication deprescribing + home safety.

FRAX: 10-year fracture probability; treatment threshold typically MOF ≥20% or hip ≥3%.

Key distinction: Osteoporosis vs osteomalacia — check alk phos and 25-OH vit D.

Board pearl: The single most under-recognized fact: a "normal" DXA after a fragility fracture does not change the diagnosis or the indication to treat.

Board Question Stem Patterns

Stem 1 — Wrist fracture sentinel: 62-year-old postmenopausal woman tripped on a curb and sustained a distal radius fracture; DXA shows T-score −1.8 at hip. Next best step? → Start alendronate plus calcium/vit D; this is a fragility fracture and meets clinical osteoporosis criteria regardless of T-score.

Stem 2 — Post-hip fracture transition: 78-year-old man discharged to SNF after ORIF of intertrochanteric fracture. Vitamin D 18 ng/mL. Next? → Replete vitamin D, then schedule IV zoledronate at 2 weeks post-op, calcium 1,200 mg/day, PT, fall prevention.

Stem 3 — Denosumab discontinuation trap: 70-year-old woman discontinued denosumab 9 months ago; now presents with multiple acute vertebral fractures. Lesson: rebound vertebral fractures after denosumab; should have been bridged with bisphosphonate.

Stem 4 — Atypical femoral fracture: 75-year-old on alendronate × 8 years with new dull thigh pain. XR: lateral cortical thickening, transverse subtrochanteric line. Next? → Stop bisphosphonate, ortho referral, switch to teriparatide, image contralateral femur.

Stem 5 — GIOP: 55-year-old man with PMR on prednisone 15 mg/day for 4 months. Next? → Start oral bisphosphonate + Ca/vit D, baseline DXA, taper steroid as feasible.

Stem 6 — Recurrent vertebral fracture despite therapy: Adherent on alendronate × 2 years with a new VCF. Next? → Rule out secondary causes (PTH, vit D, SPEP, TSH, 24-hr urine Ca), check adherence, then switch to anabolic (teriparatide or romosozumab).

Stem 7 — Premenopausal fragility fracture: 32-year-old runner with stress fracture and amenorrhea. Next? → Evaluate Female Athlete Triad / RED-S; restore energy availability and menses; not bisphosphonate first.

Stem 8 — CKD with fracture: Diabetic with eGFR 25 and new vertebral fracture. Next? → Denosumab (with close calcium/vit D monitoring) preferred over bisphosphonate.

Stem 9 — Romosozumab CV trap: Patient with recent MI 6 months ago; very high fracture risk. → Avoid romosozumab; choose teriparatide or zoledronate.

Stem 10 — Mandatory reporting: Frail elder with multiple fractures of varying ages, fearful affect, controlling caregiver. → Notify Adult Protective Services; ensure safe disposition.

Board pearl: Whenever the stem says "post-fragility-fracture" or "after hip fracture" and asks "next step," the answer almost always involves initiating bone-active therapy plus fall prevention — pick the option that does both.

One-Line Recap

Every fragility fracture is osteoporosis until proven otherwise, and every patient with one earns lifelong secondary prevention built on pharmacotherapy + calcium/vitamin D + fall prevention + structured follow-up — starting before discharge.

Treat on the fracture, not the T-score: hip or vertebral fragility fracture = osteoporosis; initiate therapy without waiting for DXA, after confirming normocalcemia and adequate vitamin D.

Match agent to risk and patient: oral bisphosphonate for standard high risk; IV zoledronate at ~2 weeks post-hip fracture; denosumab for CKD or adherence concerns (never stop without a bridge); anabolic first (teriparatide, abaloparatide, romosozumab) for very high risk, then antiresorptive to lock in gains.

Prevent the next fall and the next fracture: vitamin D ≥30 ng/mL, calcium 1,000–1,200 mg/day, protein, balance + resistance exercise, deprescribe sedating and orthostatic drugs, home safety, vaccinations, and a Fracture Liaison Service when available.

Close the loop: structured handoff from hospital → SNF → PCP, DXA in 1–2 years, BMD/CTX monitoring, vigilance for AFF/ONJ and denosumab rebound, and re-evaluation for secondary causes if a new fracture occurs on therapy.

Board pearl: The classic Step 3 wrong answer is "obtain DXA and follow up in 6 months" after a hip fracture — the correct answer is start treatment now and arrange DXA, labs, PT, and follow-up in parallel. Closing the post-fracture treatment gap is the single highest-yield intervention in musculoskeletal preventive medicine.