Metabolic & Endocrine Disorders in Orthopaedic Surgery
Skeletal Metabolism
Factors Influencing Skeletal Development
- Genetic
- Metabolic
- Endocrine
- Physical including the Heuter Volkman principle & Wolff’s Law
Calcium & Phosphorus Hemostasis
- Bone = hydroxyapetite Ca10(PO4)6(0H)2
Vit D
- Ergosterol & 7 dehydroxycholesterol from the diet
- Ergosterol + UV light in skin = calciferol Vit D2
- 7 dehydroxycholesterol + UV light = cholecalciferol Vit D3
- Vit D2 & Vit D3 in liver form 25 Vit D
- In kidney 1,25 or 24,25 Vit D3(calcitriol)
- Calcitriol acts at the gut, kidney & bone
PTH
- In response to ↓ in Ca
- PTH & Vit D in gut ↑ the absorption of Ca
- PTH & Vit D in kidney ↑ the resorption of Ca
- PTH alone works at the bone to ↑ osteoclastic activity & resorption of Ca
- PTH decreases the PO4 resorption at the kidney
- PTH ↑ Vit D3
Absorption of Ca
- Decreased by ↓ acid, chelated, salts
- In response to ↓ in Ca there is an incease in PTH which favours gut, kidney & bone resorption while decreasing the phospate
Calcitonin
- C cells in the thyroid
- Block release of Ca