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Disorders Of The Bone By Yapa Wijeratne
 

Disorders Of The Bone By Yapa Wijeratne

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Presentation on disorders of the bone which explains the biochemical & physiological aspects with illustrations.

Presentation on disorders of the bone which explains the biochemical & physiological aspects with illustrations.

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    Disorders Of The Bone By Yapa Wijeratne Disorders Of The Bone By Yapa Wijeratne Presentation Transcript

    • Disorders of the bone
      by Yapa Wijeratne
      Faculty of Medicine
      University of Peradeniya
      Sri Lanka
    • Osteoporosis
      Osteopetrosis (marble bone disease)
      Paget’s disease of bone
      Osteomalacia & rickets
      Osteogenesisimperfacta (brittle bones)
    • 1.Osteoporosis
      Relative excess of osteoclast (OC) function.
      A significant reduction of bone mineral density compared with age & sex match norms.
      ↑ susceptibility to fractures.
      Disease of aging.
      Bone density peak at 30 yrs in both sex.
      Rate of bone loss is accelerated in females ,after loss of estrogen (E2) secretion at the menopause.
      E2 inhibits stimulatory effect of certain cytokines which contribute bone resorption on OC. Thereby prevent osteoporosis. At the menopause this inhibitory effect is removed & cytokines are activated.
    • Factors ↑ the risk of osteoporosis
      Aging
      Females
      Premature menopause
      Smoking
      ↑ alcohol intake
      Excessive exercise
      Inactivity-immobilization
      Poor [Ca+2] intake
      Excessive caffeine intake
    • 2. Osteopetrosis (marble bone disease)
      Rare & often severe disease.
      characterized by increased bone density.
      OC are defective & unable to resorb bone in the usual fashion.
      One form occurs along with renal tubular acidosis and cerebral calcification.
      It is due to mutations in the gene encoding carbonic anhydrase II(provide H+ to neutralize OH-)
      Narrowing & distortion of foramina -> compress nerves ->neurologic defects.
      Crowding out of the marrow cavities ->hematological abnormalities
    • Histological appearance of bone in osteopetrosis
    • 3. Paget’s disease of bone
      Localized disorder characterized by accelerated bone turnover.
      Initiated by ↑OC mediated bone resorption.
      ↑ALP activity
      ↑Collagen breakdown by OC result in a
      ↑ [Hydroxyproline] & [collagen fragments] in urine.
    • Histological appearance of bone in Paget’s disease of bone
    • 4.Osteomalacia & rickets
      Abnormal mineralization of bone & cartilage.
      Vit D ↓ -> defective calcification of bone matrix
      Osteomalacia -> adults
      Rickets-> children
      Main defect is failure to deliver adequate amounts of [Ca+2] & [PO4-3] to the site of mineralization.
      In children ,
      Weakness & bowing of Wt bearing bones
      Dental defects
      hypocalcemia
    • 5. Osteogenesisimperfacta (brittle bones)
      Abnormal fragility of bones
      Over 90% of Pt have mutations in the COLIA1,COLIA2 genes
      ↓Expression of collagen or structurally abnormal collagen fibrils

      Weakening of bone

      Affected infants may be bone with multiple fractures & not survive
    • Radiogical appearance of the upper limbs in Osteogenesisimperfacta