Metabolic Bone Disorders Dr. Mohammed M. Zamzam Associate Professor & Consultant Pediatric Orthopedic Surgeon

Calcium Homeostasis - Bone is not only for support - Bone formation & bone resorption - Hydroxyapatite crystals - Calcium & phosphate control * Intestinal absorption * Renal excretion * Bone

Vitamin D * Sources - Diet - Ultraviolet rays on skin * Cholecalciferol activation - PTH - Phosphate concentration * Action - Intestinal absorption of Ca - Bone resorption

Parathyroid Hormone - Fine regulator of Ca exchange - Serum Ca regulate its secretion - Action * Increase phosphate excretion * Increase Ca reabsorption * Vitamin D activation

Calcitonin - C cells of thyroid gland - Serum Ca regulates its secretion - Action * Rapid hypocalcaemic effect by inhibiting bone resorption

Secondary rule Other Hormones Non-hormonal Factors - Estrogen - Corticosteroids - Thyroxin - Mechanical stress - Prostaglandin E - Acid-base balance

Rickets & Osteomalacia - Different expressions of the same disease - Inadequate mineralization - Rickets * Areas of endochondral growth - Osteomalacia * All skeleton is incompletely calcified

Rickets & Osteomalacia * Causes - Calcium deficiency - Hypophosphataemia - Defect in Vitamin D metabolism nutritional underexposure to sunlight intestinal malabsorption liver & kidney diseases

Rickets & Osteomalacia Symptoms & Signs *Rickets - Tetany or convulsions ? - Failure to thrive, muscle flaccidity - Craniotabes, joint thickening - Pigeon chest, rickety rosary, Harrison’s sulcus - Deformities

Rickets & Osteomalacia Symptoms & Signs *Osteomalacia - Bone pain, backache - Muscle weakness - Vertebral collapse kyphosis loss of height - Deformities & stress fractures

Rickets & Osteomalacia Biochemistry Hypocalcaemia,… Hypocalcuria High alkaline phosphatase

Rickets & Osteomalacia X-rays * Rickets - Growth plate widening & thickening - Metaphyseal cupping - Diaphyseal deformities * Osteomalacia - Looser zone, biconcave vertebra, protrusio acetabuli - Spontaneous fractures *Signs of secondary hyperparathyroidism

Rickets & Osteomalacia Treatment *Vitamin D deficiency - Rickets controlled Vitamin D sun exposure correct residual deformities - Osteomalacia Vit. D + Ca fracture management correct deformity if needed

Hyperparathyroidism *Primary hyperplasia - adenoma - carcinoma *Secondary persistent hypocalcaemia *Tertiary secondary leads to hyperplasia

Hyperparathyroidism Pathology - PTH overproduction - Increased renal tubular absorption, intestinal absorption and bone resorption of Ca - Hypercalcaemia and hypercalciuria - Suppressed phosphate tubular reabsorption - Hypophosphataemia and hyperphosphaturia

Hyperparathyroidism Pathology *Hypercalcaemia calcinosis, stone formation, recurrent infection and soft tissue calcification *Bone resorption loss of bone substance, subperiosteal erosion osteitis fibrosa cystica and brown tumors

Hyperparathyroidism Symptoms & Signs *Hypercalcaemia anorexia, nausea, depression and polyuria *Bone rarefaction pain, pathological fractures and deformities *Biochemistry hypercalcaemia, hypophosphataemia, high alk. Phosphatase and serum PTH

Hyperparathyroidism X-rays - Subperiosteal bone resorption - Generalized decrease in bone density - Brown tumors - Chondrocalcinosis knee, wrist and shoulder

Hyperparathyroidism Treatment Surgical excision of adenoma or hyperplastic parathyroid tissue *Hungry bone syndrome treated by vitamin D

Osteoporosis * Normal mineralization * Decrease bone mass (amount of bone per unit volume) * Age related * Associated or manifestation of other conditions

Osteoporosis Causes * Idiopathic * Nutritional * Endocrine disorders * Drug induced * Malignant diseases * Miscellaneous

Osteoporosis - Idiopathic osteoporosis - normal investigations - In old patients we have to role out malignancy and multiple myeloma - Younger patients must be fully investigated - Several causes may be involved - Osteoporosis can be associated with osteomalacia

Osteoporosis Symptoms & Signs - Bony aches - Easy fractures spine - lower radius - femoral neck - Rib fracture, chest pain - Normal biochemistry

Osteoporosis X-rays - Decrease bone density - Wedging or biconcave vertebrae - Thin cortex and deformities - Dexa Scan - Biopsy

Osteoporosis Treatment - Treat underlying cause - Idiopathic, extremely difficult - Calcium and vitamin D - Fluoride and triple therapy - Calcitonin, Diphosphonate - Treat fractures

Osteoporosis Prevention * Good diet * Exercise * Exposure to sun light * Ca supplement * Hormone therapy