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Paget's Disease/Osteitis Deformans

  1. It is characterized by excessive disorganized bone turnover, that encompasses excessive osteoclastic activity initially followed by disorganized excessive new bone formation. It is the osteoclast that appear larger & irregular whereas osteoblast are relatively normal.
  2. The new bone formed is abnormal i.e. lacks strength (so deforms & fractures), very vascular & larger than preexisting bone which leads to cortical widening and contributes to the deformity.
  3. The diagnostic histological feature of pagets disease is irregular areas of lamellar bone fitting together like a jigsaw with randomly distributed cement lines.
  4. It either occurs in one bone (monostotic Paget’s disease) or multiple bones (poly ostotic Paget’s disease) 
Etiology - Genetic infection by paramyxovirus (measles & respiratory syncytial virus)

  1. Increased bone resorption accompanied by accelerated bone formation is characteristic feature.
  2. Initial osteolytic phase involves prominent bone resorption & marked hypervascularization (Radiologically seen as advancing lytic wedge or blade of grass lesion)
  3. 2nd phase of active bone formation & resorption replaces normal lamellar bone with structurally weak woven bone that bend, bow & fracture easily)
  4. In 3rd sclerotic (burnt out) phase, bone resorption declines progressively & leads to hard, dense, less vascular pagetic or mosaic bone
Clinical features
  1. It is rare below 20, and most are over 50 years
  2. Most people are asymptomatic (diagnosed by ↑ALP or X-ray)
  3. The sites most commonly involved are — pelvis, tibia, followed by skull, spine, clavicle & femur
  4. Affects men & women equally
  5. Pain is most common presenting symptom
  6. Limb look bent & feels thick, and skin s unduly warm due to high vascularity hence the name ostetis deformans. Skull show frontal bossing & platybasia
  1. Pagetoid bone lacks the strength of normal bone. As a result it deforms & fractures more easily.
  2. Fractures & osteoarthritis
  3. Cranial nerve Compression & spinal stenosis
  4. Deafness due to nerve compression & otosclerosis.
  5. High output cardiac failure
  6. Hypercalcemia & steal syndromes (if immobilized) Steal syndrome i.e. blood is diverted from internal organs to skeleton system may lead to cerebral ischemia & spinal claudication.
  7. Osteosarcoma -<1% cases.
  1. Increased marker of bone formation
    1. S. alkaline phosphatase
    2. S. Osteocalcin
  2. Serum calcium and phosphate levels are usually normal.
  3. Increased markers of bone resorption
    1. serum & urinary deoxypyridinoline, N telopeptine & C-telopeptide
    2. Urinary hydroxy proline
  4. Radiological features
    1. Long bone x-ray show deformity enlargement or expansion of bone with cortical thickening coarsening of trabecular markings and lytic & sclerotic changes
    2. Skull x-ray reveal “cotton wool” or osteoporosis circumscripta thickening of diploic area
    3. Vertebral cortical thickening at superior & inferior end plates creates a picture frame vertebrae & diffuse sclerosis - ivory vertebrae


“cotton wool”

Picture Frame Vertebra

Blade of grass
  1. Pelvic radiograph show sclerotic ileopectinal line (Brim sign), fusion or disruption of sacroiliac joints etc.
  1. Indications are
    1. To control symptoms of active disease as bone pain, fracture, headache, neurological complications or pain from radiculopathy or arthropathy
    2. To decrease local blood flow & minimize operative blood loss in patients undergoing surgery
    3. To decrease hypercalciuria due to immobilization
    4. To decrease complications
    5. When site of involvement involves weight bearing bones, skull, vertebral bodies & major joints.
  2. Biphosphonates are drug of choice and calcitonin is drug of 2 choice.
  3. Etidronate is 1st used; Risedronate is most potent. Alendronate is also used.
  4. Pain is relieved by calcitonin.

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