Synopsis
Distinguish active pagetic bone pain from mechanical joint and fracture complications, map affected sites and coordinate antiresorptive treatment with safe deformity, fixation and arthroplasty planning.
- Paget disease is focal accelerated remodelling that produces expanded, hypervascular and mechanically disorganised bone, commonly affecting pelvis, spine, femur, tibia and skull.
- First-line confirmation uses radiographs of suspected sites plus total ALP with liver tests; normal ALP does not exclude limited monostotic disease.
- After characteristic radiographic diagnosis, radionuclide bone scintigraphy is the reference test for mapping active skeletal extent, with radiographic correlation of unexpected uptake.
- Decide what causes pain: active bone, an incomplete fissure fracture, secondary osteoarthritis, spinal stenosis, nerve compression or sarcoma require different interventions.
- Bisphosphonate treatment is first-line for pain attributable to active Paget disease; a single 5 mg intravenous zoledronic-acid infusion gives the most durable biochemical response when safe.
- Do not treat an isolated ALP result or chase biochemical normality in every asymptomatic patient; target symptoms and defined complication risk.
- Protect weight bearing and image the whole bowed femur or tibia when new focal lateral-cortex pain suggests an incomplete pagetic fracture.
- Plan osteotomy, fixation or arthroplasty with an experienced team because deformity, sclerosis, altered anatomy and hypervascularity change implant choice and blood-loss preparation.
Key red flags
A new fracture through expanded femur or tibia can bleed, displace and be technically difficult to stabilise; protect the limb and refer urgently.
New neurological deficit, gait deterioration or sphincter change with vertebral enlargement suggests canal compromise requiring emergency spinal assessment.
Rapidly increasing focal pain, soft-tissue mass, cortical destruction or a new lytic focus may represent osteosarcoma arising in pagetic bone.
Headache with abrupt hearing, cranial-nerve or basilar-invagination symptoms needs targeted skull-base and neurological assessment rather than routine ALP monitoring.
Warmth and raised ALP with fever or markedly raised inflammatory markers can reflect infection, malignancy or another process rather than uncomplicated activity.
Hypercalcaemia during prolonged immobilisation or dehydration requires urgent biochemical assessment and treatment of the precipitating condition.
Investigation priorities
Confirm characteristic architecture, identify deformity and fracture and screen for an aggressive alternative.
Management branches
Characteristic symptoms, incidental imaging or isolated bone-source ALP raises suspicion.
- Obtain targeted radiographs and total ALP with liver, calcium, phosphate, renal and vitamin-D tests.
- Confirm typical anatomy before ordering a radionuclide scan to map active skeletal distribution.
- Correlate additional uptake with radiographs or cross-sectional imaging rather than labelling every focus pagetic.
- Refer atypical destruction or mass directly to a bone-tumour service before any local biopsy.