Paget Disease of Bone

Paget disease of bone is focal disordered bone remodelling with excessive resorption and disorganised new bone formation.

• Prevalence 1 to 2% over age 55 in the UK/Europe, rising with age, declining incidence in some regions; familial in 15 to 40% (SQSTM1 mutations).
• Sites: pelvis, spine, skull, femur, tibia.
• Complications: pain, deformity, fractures, osteoarthritis, deafness, nerve compression, high output heart failure (extensive), hypercalcaemia (immobilisation), osteosarcoma (under 1%).

• Often asymptomatic, found by raised alkaline phosphatase or radiograph.
• Bone pain, warmth over affected bone, bowing of tibia, enlarged skull (hat size increase), hearing loss, headaches, spinal stenosis, basilar invagination.
• Pathological fracture (transverse "banana" fractures).
• Sudden worsening pain and swelling suggests sarcoma.

• Alkaline phosphatase raised (total or bone specific), calcium and phosphate normal; PINP, CTX markers of turnover.
• Radiographs: lytic lesions (osteoporosis circumscripta, "blade of grass" in long bones), sclerosis, cortical thickening, bone expansion.
• Technetium bone scintigraphy shows extent; CT/MRI for complications.
• Audiometry if skull involvement, echocardiography in extensive disease.

• Indications for treatment: symptomatic (bone pain), active disease in weight bearing bones, skull base, near joints, spine, or hypercalcaemia; prophylaxis before orthopaedic surgery.
• Zoledronic acid 5 mg IV single infusion (first line, remission in over 90% lasting years); risedronate 30 mg daily for 2 months, alendronate 40 mg daily for 6 months; pamidronate 30 to 60 mg IV.
• Ensure vitamin D replete and calcium intake adequate before treatment.
• Analgesia (paracetamol, NSAIDs), orthotics, physiotherapy; surgery for fractures, joint replacement, nerve decompression, osteotomy.
• Monitor ALP every 3 to 6 months, retreat on relapse (ALP rise above reference).
• Sarcoma: biopsy and oncological management.