Rickets

  

• Osteomalacia during enchondral bone growth
• Age
  • 4-18 months
• Histology
  • Zone of preparatory calcification does not form resulting in build-up of maturing cartilage cells
  • Also occurs in shafts so that osteoid production elevates periosteum
• Clinical findings
  • Irritability
  • Bone pain
  • Tenderness
  • Craniotabes
  • Rachitic rosary
  • Bowed legs
  • Delayed dentition
  • Swelling of wrists and ankles
• Location
  • Metaphyses of long bones subjected to stress are particularly involved
    • Wrists
    • Ankles
    • Knees
• Imaging findings
  • Cupping and fraying of metaphysis
  • Poorly mineralized epiphyseal centers with delayed appearance
  • Irregular widened epiphyseal plates (increased osteoid)
  • Increase in distance between end of shaft and epiphyseal center
  • Cortical spurs projecting at right angles to metaphysis
  • Coarse trabeculation (not the ground-glass pattern found in scurvy)
  • Periosteal reaction may be present

Metaphyseal cupping and fraying in the
distal radius and ulna in rickets

• Deformities common
  • Bowing of long bones
  • Molding of epiphysis
  • Fractures
  • Frontal bossing

• Causes Of Rickets
  • Abnormality In Vitamin D Metabolism
    • Associated with hyperparathyroidism
    • Vitamin D deficiency
      • Dietary lack of vitamin D
      • Famine osteomalacia
    • Lack of sunshine exposure
    • Malabsorption of vitamin D
      • Pancreatitis and biliary tract disease
      • Steatorrhea, celiac disease, postgastrectomy
      • Inflammatory bowel disease
  • Defective conversion of vitamin D to 25-OH-cholecalciferol in liver
    • Liver disease
    • Anticonvulsant drug therapy (= induction of hepatic enzymes that accelerate degradation of biologically active vitamin D metabolites)
  • Defective conversion of 25-OH-D3 to 1,25-OH-D3 in kidney
    • Chronic renal failure = renal osteodystrophy
    • Vitamin D-dependent rickets = autosomal recessive enzyme defect of 1-OHase
• Abnormality In Phosphate Metabolism
  • Not associated with hyperparathyroidism secondary to normal serum calcium
  • Phosphate deficiency
    • Intestinal malabsorption of phosphates
    • Ingestion of aluminum salts [Al(OH)2] forming insoluble complexes with phosphate
    • Low phosphate feeding in prematurely born infants
    • Severe malabsorption state
    • Parenteral hyperalimentation
    • Disorders of renal tubular reabsorption of phosphate
      • Renal tubular acidosis (renal loss of alkali)
      • deToni-Debré-Fanconi syndrome = hypophosphatemia, glucosuria, aminoaciduria
      • Vitamin D-resistant rickets
      • Cystinosis
      • Tyrosinosis
      • Lowe syndrome
  • Hypophosphatemia with nonendocrine tumors
    • Oncogenic rickets - elaboration of humeral substance which inhibits tubular reabsorption of phosphates
      • Sclerosing hemangioma
      • Hemangiopericytoma
      • Ossifying mesenchymal tumor
      • Nonossifying fibroma
  • Hypophosphatasia
• Calcium Deficiency
  • Dietary rickets = milk-free diet (extremely rare)
  • Malabsorption
  • Consumption of substances forming chelates with calcium
• Classification Of Rickets
  • Primary vitamin D-deficiency rickets
  • Gastrointestinal malabsorption
    • Partial gastrectomy
    • Small intestinal disease: gluten-sensitive enteropathy / regional enteritis
    • Hepatobiliary disease: chronic biliary obstruction / biliary cirrhosis
    • Pancreatic disease: chronic pancreatitis
  • Primary hypophosphatemia; vitamin D-deficiency rickets
  • Renal disease
    • Chronic renal failure
    • Renal tubular disorders: renal tubular acidosis
    • Multiple renal defects
• Hypophosphatasia and pseudohypophosphatasia
  • Fibrogenesis imperfecta osseum
  • Axial osteomalacia
• Miscellaneous
  • Hypoparathyroidism, hyperparathyroidism, thyrotoxicosis, osteoporosis, Paget disease, fluoride ingestion,
  • ureterosigmoidostomy, neurofibromatosis, osteopetrosis, macroglobulinemia, malignancy

Dahnert 4th edition