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Paget’s Disease of Bone

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Overview

Paget’s disease of bone is a result of increased but uncontrolled burn turnover, leading to the development of new bone that is disorganised, mechanically weaker, and more liable to pathological fractures and deformity.

The thoracic spine, sacrum, humerus and long bones of the lower limb are usually affected. The hands and feet are rarely affected.

Epidemiology

  • More common in males
  • Peak incidence is >70 years

Risk Factors & Associations

  • Family history
  • Age >50 years
  • Male sex

Presentation

  • Most patients are asymptomatic
  • Bone pain in the pelvis, lumbar spine, or femur
  • If untreated, features of tibial bowing prognathism, and bossing of the skull may be seen
  • Pathological fractures may be the presenting complaint

Differential Diagnoses

Osteomalacia

  • Difficult to differentiate
  • Osteomalacia has bone pain from its onset
  • Most people with Paget’s disease of bone are asymptomatic
  • Osteomalacia: low serum vitamin D and raised ALP
  • Paget’s disease of bone: classically isolated raised ALP

Investigations

  • Bone profile tests should be carried out:
    • All results are normal except for an isolated rise in ALP
  • Plain X-rays are then carried out of the affected regions:
    • Lytic changes seen often in the skull
    • In later stages, sclerotic changes are seen
    • The pelvis, long bones, and skull are the most common sites of abnormal bone
    • A skull x-ray may show a thickened vault

Management

  • If patients are asymptomatic:
    • 1st line: observation and preventative measures
  • If patients are asymptomatic but have a high risk of complications:
    • 1st line: bisphosphonate or calcitonin (less commonly used)
  • If patients are symptomatic:
    • 1st line: bisphosphonate or calcitonin (less commonly used) 

Patient Advice

  • Patients should avoid high-impact activities such as weight lifting, as these may cause pathological fractures
  • Patients should report any changes in their symptoms
    • This may indicate fracture or in rare cases, the development of osteosarcoma

Complications

  • Pathological fractures
  • Kidney stones
  • Deafness/tinnitus secondary to cranial nerve entrapment
  • Spinal stenosis
  • Arthritis
  • Development of osteosarcoma – rare
  • High-output cardiac failure – extremely rare
    • Due to high blood flow to highly metabolically active bone sites

Prognosis

  • Depends on the extent and degree of disease activity
  • Remission may be possible with effective treatment
  • Patients developing osteosarcoma have a very poor prognosis

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