Pathological fracture

Overview

A fracture occurring in bone already weakened by disease - the force required is far less than needed to break healthy bone.

Presentation

Fracture after minimal or trivial trauma - the defining clinical clue; mechanism does not match injury
Bone pain - deep, constant, worse at night; may precede fracture by weeks
Systemic red flags - weight loss, fatigue, anorexia, night sweats suggest underlying malignancy
Vertebral fracture - acute back pain, height loss, kyphosis; neurological symptoms suggest spinal cord compression

Investigations

🥇 First-line

Plain X-ray - fracture + lytic/sclerotic lesions, cortical destruction
Serum calcium, phosphate, ALP, PTH - distinguishes metabolic causes
FBC, renal function, serum protein electrophoresis, urine Bence Jones protein - screen for myeloma
Isotope bone scan (Tc-99m) - multiple metastatic deposits; note myeloma may be cold/normal

🥈 Second-line

MRI - vertebral fractures, spinal cord assessment; mandatory if neurological symptoms
CT chest/abdomen/pelvis - staging and identifying primary tumour

🏆 Gold standard

Bone biopsy - histological confirmation when primary unknown

Management

Treat underlying cause - systemic therapy for myeloma; radiotherapy for painful bone metastases; bisphosphonates or denosumab for bone protection in malignancy/osteoporosis; risedronate or zoledronic acid for Paget's
Analgesia - WHO ladder; bone pain from malignancy often responds to NSAIDs and bisphosphonates alongside opioids
Surgical stabilisation - intramedullary nailing for long bone fractures; vertebroplasty or kyphoplasty for vertebral compression fractures in selected patients
Spinal cord compression - dexamethasone 16 mg/day immediately + urgent MRI spine + neurosurgical/oncological review
🚨
Spinal cord compression is a medical emergency. New neurological symptoms (weakness, sensory loss, bladder/bowel dysfunction) in a vertebral fracture patient requires urgent MRI spine and immediate dexamethasone - do not delay imaging for bloods.

Cancers that metastasise to bone

🧠
PoRTaBLe: Prostate, Renal, Thyroid, Breast, Lung. Breast and prostate - osteosclerotic. Renal, thyroid, lung - osteolytic. Myeloma - purely lytic 'raindrop' lesions.

Differential diagnosis - key distinguishing features

🎯
ALP is a marker of osteoblast activity - suppressed in myeloma so ALP is characteristically NORMAL despite extensive bone destruction. Hypercalcaemia + anaemia + thrombocytopenia + renal impairment + normal ALP = myeloma until proven otherwise.
🧠
CRABBI mnemonic for myeloma features: Calcium (raised), Renal impairment, Anaemia, Bleeding (thrombocytopenia), Bones (lytic lesions), Infection (immunosuppression).