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.

Published in: Health & Medicine

Disorders Of The Bone By Yapa Wijeratne

  1. 1. Disorders of the bone<br />by Yapa Wijeratne<br />Faculty of Medicine<br />University of Peradeniya<br />Sri Lanka<br />
  2. 2. Osteoporosis <br />Osteopetrosis (marble bone disease)<br />Paget’s disease of bone<br />Osteomalacia & rickets <br />Osteogenesisimperfacta (brittle bones)<br />
  3. 3. 1.Osteoporosis <br />Relative excess of osteoclast (OC) function.<br />A significant reduction of bone mineral density compared with age & sex match norms.<br />↑ susceptibility to fractures.<br />Disease of aging.<br />Bone density peak at 30 yrs in both sex.<br />Rate of bone loss is accelerated in females ,after loss of estrogen (E2) secretion at the menopause.<br />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.<br />
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  5. 5. Factors ↑ the risk of osteoporosis<br />Aging <br />Females<br />Premature menopause<br />Smoking <br />↑ alcohol intake<br />Excessive exercise<br />Inactivity-immobilization<br />Poor [Ca+2] intake <br />Excessive caffeine intake<br />
  6. 6. 2. Osteopetrosis (marble bone disease)<br />Rare & often severe disease.<br />characterized by increased bone density.<br />OC are defective & unable to resorb bone in the usual fashion. <br />One form occurs along with renal tubular acidosis and cerebral calcification. <br />It is due to mutations in the gene encoding carbonic anhydrase II(provide H+ to neutralize OH-)<br />Narrowing & distortion of foramina -> compress nerves ->neurologic defects.<br />Crowding out of the marrow cavities ->hematological abnormalities <br />
  7. 7. Histological appearance of bone in osteopetrosis<br />
  8. 8. 3. Paget’s disease of bone<br />Localized disorder characterized by accelerated bone turnover.<br />Initiated by ↑OC mediated bone resorption. <br />↑ALP activity<br />↑Collagen breakdown by OC result in a <br />↑ [Hydroxyproline] & [collagen fragments] in urine.<br />
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  10. 10. Histological appearance of bone in Paget’s disease of bone<br />
  11. 11. 4.Osteomalacia & rickets <br />Abnormal mineralization of bone & cartilage.<br />Vit D ↓ -> defective calcification of bone matrix<br />Osteomalacia -> adults<br />Rickets-> children<br />Main defect is failure to deliver adequate amounts of [Ca+2] & [PO4-3] to the site of mineralization.<br />In children ,<br />Weakness & bowing of Wt bearing bones<br />Dental defects<br />hypocalcemia<br />
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  13. 13. 5. Osteogenesisimperfacta (brittle bones)<br />Abnormal fragility of bones<br />Over 90% of Pt have mutations in the COLIA1,COLIA2 genes<br />↓Expression of collagen or structurally abnormal collagen fibrils<br /> ↓<br />Weakening of bone<br /> ↓<br />Affected infants may be bone with multiple fractures & not survive <br />
  14. 14. Radiogical appearance of the upper limbs in Osteogenesisimperfacta<br />

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