paget's%20bone%20disease
PAGET'S BONE DISEASE
Paget's bone disease, also known as osteitis deformans, is characterized by a significant increase in bone resorption and turnover in localized parts of the skeleton causing enlargement and thickening of the bone that is disordered and architecturally unstable.
The prevalence increases with age, with men and women affected equally.
Genetic factors and/or viral infection may play a role in the etiology.
May affect one bone (monostotic) or several bones (polyostotic).
By decreasing frequency, involved bones may include pelvic bone and sacrum, spine, skull and femur, tibia, humeri and clavicles.

Paget's%20bone%20disease Diagnosis

Diagnosis

  • Patient should be treated depending on the following:
    • Signs and symptoms of active Paget’s bone disease (eg pain at pagetic site and bone deformity)
    • Asymptomatic but with biochemically active Paget’s bone disease likely to cause complications in the future (eg skull base involvement that may lead to deafness)
    • Sites of pagetic lesions
    • Metabolic activity as determined by bone scan or bone turnover markers
    • Heart disease and extensive Paget’s bone disease
  • Patient with hypercalcemia resulting from immobilization should receive pharmacotherapy

Laboratory Tests

  • Serum total alkaline phosphatase (ALP) is recommended as the 1st-line biochemical screening test for patients suspected with Paget's bone disease 
  • Measure biochemical markers to monitor the degree of bone formation and resorption
  • Bone turnover: Measure serum alkaline phosphatase (ALP) or bone specific alkaline phosphatase (ALP) if the previous is normal
    • Serum alkaline phosphatase (ALP) rises further if patient develops osteosarcoma
  • Bone resorption: Measure type I collagen breakdown markers (eg serum C-telopeptide or urinary N-telopeptide)
  • Serum calcium may be elevated in extensive Paget’s disease that causes immobilization
  • Urinary excretion of calcium and phosphorus may be normal or increased

Imaging

X-ray

  • Confirms the diagnosis of Paget’s bone disease
  • X-rays of the abdomen, facial bones, skull and both tibias are recommended as an initial diagnostic screening tool in patients suspected with Paget's bone disease
    • Detect 93% of bone lesions compared with 79% for an abdominal x-ray alone
  • Findings include osteoporosis circumscripta in the skull, flame-shaped lesions in long bones, osteolytic lesions near thickened lesions, sclerotic bone, bowed limbs, fractures (ie “banana” or “chalk” transverse fractures)

Radionuclide Bone Scan

  • Most sensitive test in identifying pagetic bone lesions
  • Determines extent of bone involvement
  • May also identify possible asymptomatic bones
  • Areas of increased uptake of technetium-99m
  • “Mouse face, clover or heart sign” pattern on scan of affected vertebra

Computed Tomography (CT) Scan and Magnetic Resonance Imaging (MRI)

  • Enlarged bones with trabecular coarsening and increased cortical thickness may be seen in cross-sectional CT or MRI
  • Anatomy is well demonstrated in complex structures (eg spine)
  • Recommended for assessment of Paget's disease complications (eg basilar invagination, osteosarcoma, spinal stenosis)
    • Not routinely used as initial diagnostic tool

Complications

  • Complications include fractures and/or fissures due to bone fragility, neurologic symptoms from nerve compression due to bone overgrowth or interference with blood supply, heart failure due to increased stress on the heart, and most serious complication is development of bone malignancy

Hearing loss

  • A potential complication of Paget's disease when the temporal bone is involved

Osteoarthritis

  • A relatively common complication, particularly in weightbearing joints such as the hip or knee

Paralysis

  • Paraplegia occurs when there is a Paget's disease of the spine

Bowing of lower extremity

  • Associated with impaired ambulation and/or severe joint pain

Neoplasms

  • A rare complication that arise from pagetic bone due to osteoblast proliferation

Congestive heart failure

  • High output cardiac failure may occur, but is not common
  • Both high cardiac output and low peripheral vascular resistance are present for patients suffering from extensive skeletal improvement
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